Termination Of Pregnancy
Termination of pregnancy is the deliberate ending of a pregnancy by medical (pharmacological) or surgical means before the fetus reaches viability.
Termination of Pregnancy (TOP)
Termination of pregnancy (TOP), also known as induced abortion, refers to the deliberate ending of a pregnancy before the fetus reaches viability through medical or surgical means. This is distinct from spontaneous abortion (miscarriage), which occurs without intentional intervention.
Breaking down the terminology:
- "Termination" = bringing to an end
- "of Pregnancy" = the gestational state
In Hong Kong, TOP is governed by specific legislation and is only legally performed under defined conditions (discussed below). Globally, TOP encompasses a spectrum — from early medical abortion using pharmacological agents to second-trimester surgical procedures.
Key Distinction
Spontaneous abortion (miscarriage) = pregnancy loss without deliberate intervention. Induced abortion (TOP) = deliberate intervention to end a pregnancy. Therapeutic abortion = TOP performed for medical indications (maternal health, fetal anomaly). Elective abortion = TOP performed at the woman's request (where legally permitted). In Hong Kong's legal framework, all legal TOPs are essentially "therapeutic" — they require specific grounds to be met.
Epidemiology
- Worldwide, approximately 73 million induced abortions occur annually (WHO, 2024 estimates) [1]
- Approximately 45% of all abortions globally are considered "unsafe" (performed by persons lacking necessary skills or in environments not conforming to minimal medical standards)
- Unsafe abortion remains a leading cause of maternal mortality, accounting for 4.7–13.2% of maternal deaths globally
- Rates are highest in regions with restrictive abortion laws — paradoxically, restricting access does not reduce abortion rates but shifts them to unsafe settings
- In Hong Kong, TOP is legally regulated under the Offences Against the Person Ordinance (Cap. 212) and the specific exemption provisions [2]
- The number of legal TOPs in Hong Kong has been declining over recent decades, reflecting improved contraceptive access and education
- In 2022, approximately 7,000–9,000 legal TOPs were performed in Hong Kong (Hospital Authority data)
- The majority are performed in the first trimester ( < 12 weeks)
- The most common indications in Hong Kong include: risk to physical/mental health of the woman, and fetal anomaly [2]
- Peak age group: 20–34 years
- Both nulliparous and multiparous women seek TOP
- In Hong Kong, a significant proportion are among married women (unlike some Western contexts where the majority are unmarried)
Legal Framework in Hong Kong
This is critical because the legality directly determines clinical practice.
Under Hong Kong law (Offences Against the Person Ordinance, Cap. 212, Sections 46-47), abortion is a criminal offence UNLESS specific conditions are met [2]:
Legal grounds for TOP in Hong Kong [2]:
- The pregnancy has NOT exceeded 24 weeks, AND
- Two registered medical practitioners are of the opinion, formed in good faith, that:
- Continuance of the pregnancy would involve risk to the life of the pregnant woman greater than if the pregnancy were terminated, OR
- Continuance of the pregnancy would involve risk of injury to the physical or mental health of the pregnant woman greater than if the pregnancy were terminated, OR
- There is substantial risk that if the child were born, it would suffer from such physical or mental abnormalities as to be seriously handicapped
OR, regardless of gestational age:
- The termination is immediately necessary to save the life of the pregnant woman, OR
- The termination is immediately necessary to prevent grave permanent injury to the physical or mental health of the pregnant woman
The procedure must be performed by a registered medical practitioner in an approved institution (i.e., a hospital) [2].
Exam High Yield — Legal Requirements for TOP in HK
For a legal TOP in Hong Kong, you need:
- Two doctors' opinions (formed in good faith)
- Gestational age ≤ 24 weeks (for non-emergency indications)
- Performed in an approved institution by a registered medical practitioner
- Meets one of the specified grounds (maternal life/health risk, or serious fetal handicap)
Exception: No gestational limit if immediately necessary to save the woman's life or prevent grave permanent injury.
Note: Unlike the UK (which has similar legislation), Hong Kong does NOT have a specific ground for "social" abortion — but in practice, risk to mental health is interpreted broadly.
Common Exam Mistake
Students often confuse the legal gestational limit. In Hong Kong, the limit is 24 weeks for the standard indications. There is NO upper gestational limit when TOP is immediately necessary to save the woman's life or prevent grave permanent injury. Do NOT confuse this with viability limits or other jurisdictions' laws.
- The woman herself must give informed consent [2]
- For girls under 16 years, parental/guardian consent is required
- The partner's consent is NOT legally required (though counselling may involve the partner)
- Adequate counselling should be provided before and after the procedure, including discussion of alternatives (continuing pregnancy, adoption) [2]
Anatomy and Function — Relevant Review
Understanding the anatomy is essential for appreciating both the procedures and the complications.
-
Uterus: A pear-shaped muscular organ, approximately 7–8 cm long in the non-pregnant state
- Fundus: The dome-shaped portion above the tubal ostia
- Body (corpus): The main part; contains the endometrium (where the embryo implants)
- Isthmus: Narrow segment between body and cervix — becomes the lower uterine segment in pregnancy
- Cervix: The cylindrical lower portion projecting into the vagina
- Internal os: Upper opening of the cervical canal into the uterine cavity
- Cervical canal: Contains mucus-secreting glands; the canal is ~2.5 cm long
- External os: Lower opening into the vagina; nulliparous = circular, parous = slit-like
-
Myometrium: Three layers of smooth muscle
- Outer longitudinal
- Middle interlacing (figure-of-eight pattern) — this is the "living ligature" layer that compresses blood vessels after placental delivery to achieve haemostasis
- Inner circular
-
Blood supply: Uterine arteries (branches of internal iliac) → arcuate arteries → radial arteries → spiral arteries (in the endometrium). The spiral arteries are remodelled during pregnancy by trophoblast invasion to create low-resistance, high-flow vessels for placental perfusion.
-
Cervical anatomy for TOP: The cervix must be dilated for surgical TOP. The internal os is the narrowest point and the main barrier. Forced, rapid dilation risks cervical tears and cervical incompetence.
-
First trimester (≤12 weeks):
- Uterus remains within the pelvis
- Cervix is firm, closed
- Gestational sac and embryo/fetus are relatively small
- Placentation is still maturing
-
Second trimester (13–24 weeks):
- Uterus is abdominal
- Greater vascularity → increased bleeding risk
- Fetus is larger → requires more cervical dilation for surgical evacuation or induction for medical
- Placenta is well-established → higher risk of retained products and haemorrhage
Etiology (Reasons/Indications for TOP)
The "etiology" of TOP is essentially the reasons women seek it. These map onto the legal grounds.
-
Risk to maternal physical health
- Severe cardiac disease (e.g., Eisenmenger syndrome, severe pulmonary hypertension — pregnancy carries >30% mortality)
- Severe renal disease
- Malignancy requiring treatment incompatible with pregnancy (e.g., certain chemotherapy regimens, pelvic radiation)
- Severe pre-existing medical conditions worsened by pregnancy
-
Risk to maternal mental health
- Pre-existing or pregnancy-related psychiatric illness (severe depression, psychosis)
- Social circumstances contributing to psychological distress
- In practice in Hong Kong, this is the most commonly invoked ground — many women cite inability to cope, relationship breakdown, financial hardship, or unwanted pregnancy as causing significant mental distress
-
Immediately necessary to save life / prevent grave injury
- Ruptured ectopic pregnancy (though this is usually managed as a gynaecological emergency rather than "TOP" per se)
- Severe pre-eclampsia / eclampsia at pre-viable gestation
- Septic abortion with maternal compromise
- Serious fetal anomaly (substantial risk of serious handicap)
- Chromosomal abnormalities: Trisomy 13 (Patau), Trisomy 18 (Edwards), Trisomy 21 (Down syndrome — this is nuanced and involves extensive counselling)
- Structural anomalies: anencephaly, severe spina bifida, severe cardiac malformations, bilateral renal agenesis (Potter sequence)
- Genetic conditions: severe forms of thalassaemia (particularly relevant in Hong Kong where α- and β-thalassaemia carrier rates are high — approximately 8.5% of the HK population are carriers), severe metabolic disorders
- Multiple anomalies incompatible with life
Hong Kong Relevance — Thalassaemia
Hong Kong has a high carrier rate for thalassaemia (~8.5%). Antenatal screening identifies at-risk couples. If both parents are carriers, there is a 25% chance of a severely affected child (e.g., Bart's hydrops fetalis in α-thalassaemia major, or transfusion-dependent β-thalassaemia major). TOP may be offered after prenatal diagnosis confirms an affected fetus.
- Failed contraception (including failed emergency contraception)
- Unplanned/unwanted pregnancy
- Pregnancy resulting from sexual assault
- Molar pregnancy (hydatidiform mole — requires evacuation, which is technically a form of TOP)
Risk Factors for Needing TOP / Risk Factors for Complications of TOP
These overlap with contraceptive failure / non-use:
- Lack of access to effective contraception
- Incorrect or inconsistent use of contraception
- Oral contraceptive pills — efficacy reduced by missed pills, vomiting/diarrhoea, enzyme-inducing drugs [3]
- Young age / adolescence — less consistent contraceptive use, less access, less knowledge
- Low socioeconomic status
- Relationship instability
- Substance abuse — impaired judgment
- Sexual assault
- Failed sterilization (rare but occurs)
Understanding these guides pre-procedure assessment:
| Risk Factor | Mechanism / Why It Matters |
|---|---|
| Advanced gestational age | Larger uterus, more vascular, larger fetus → more dilation needed → ↑ risk of perforation, haemorrhage, retained products |
| Multiparity / grand multiparity | Softer, more compliant uterus → paradoxically ↑ risk of uterine perforation |
| Previous caesarean section / uterine surgery | Scar tissue → potential weakness → ↑ perforation risk at scar site |
| Uterine fibroids | Distort anatomy, may impede complete evacuation, ↑ bleeding risk |
| Cervical stenosis | Difficult dilation → ↑ risk of cervical laceration, false passage |
| Uterine anomalies (bicornuate, septate) | Altered anatomy → ↑ risk of incomplete evacuation, perforation |
| Coagulopathy | ↑ bleeding risk |
| Infection (pre-existing PID / cervicitis) | ↑ risk of post-procedural sepsis |
| Operator inexperience | Technical complications |
Classification of TOP Methods
TOP methods are classified by:
- Timing / Gestational age
- Method (Medical vs. Surgical)
| Period | Gestational Age | Preferred Methods |
|---|---|---|
| Early first trimester | ≤ 9 weeks (63 days) | Medical (mifepristone + misoprostol) or surgical (MVA) |
| First trimester | 9–12 weeks | Surgical (suction/vacuum aspiration) preferred; medical also possible |
| Early second trimester | 13–14 weeks | Surgical (D&E) or medical |
| Mid/late second trimester | 15–24 weeks | Medical (mifepristone + misoprostol/gemeprost induction) or surgical (D&E by experienced operator) |
By Method
Uses pharmacological agents to induce expulsion of the pregnancy. Think of it as "inducing a miscarriage."
Key drugs [3]:
-
Mifepristone (RU-486) — "mife" from anti-progestogen
- Breaking down the name: "mife-" = from the original research designation; "-pristone" = related to progesterone receptor
- Mechanism: Competitive progesterone receptor antagonist [3]
- Blocks the action of progesterone at the receptor level
- Progesterone is essential for maintaining the decidua (endometrial lining in pregnancy) and suppressing uterine contractility
- By blocking progesterone → decidual necrosis → detachment of the pregnancy → cervical softening and dilation → sensitization of myometrium to prostaglandins
- Dose: 200 mg orally (single dose) [3]
- Used as the "priming" agent, given 24–48 hours before the prostaglandin
-
Misoprostol — a synthetic prostaglandin E1 (PGE1) analogue
- Breaking down: "miso-" from the chemical structure; "-prostol" = prostaglandin
- Mechanism: Acts on myometrial smooth muscle to cause uterine contractions; also causes cervical softening and dilation [3]
- Routes: oral, sublingual, buccal, vaginal [3]
- Vaginal route has highest bioavailability and most sustained effect but slower onset
- Sublingual has fastest onset but more side effects (diarrhoea, shivering)
- Dose varies by gestational age and protocol [3]:
- ≤ 9 weeks: Mifepristone 200 mg PO → 24–48h later → Misoprostol 800 μg vaginally/sublingually/buccally
- Second trimester: Mifepristone 200 mg PO → 36–48h later → Misoprostol 400 μg vaginally q3h (repeated doses)
-
Gemeprost — a synthetic PGE1 analogue (vaginal pessary)
- Used mainly for second-trimester TOP [3]
- Mechanism: Same as misoprostol — uterine contractions + cervical ripening
- Must be stored at -10°C to -20°C (requires cold chain) — a practical disadvantage compared to misoprostol
- Dose: 1 mg pessary vaginally every 3 hours (max 5 pessaries in 24 hours)
-
Extra-amniotic prostaglandins — less commonly used now; involves instilling prostaglandins (e.g., PGF2α) through a catheter placed between the membranes and the uterine wall
Oxytocin — may be used as an adjunct, particularly in second-trimester medical TOP, to augment uterine contractions after cervical priming [3]
Why Mifepristone + Misoprostol Together?
Neither drug alone is as effective as the combination. Mifepristone "primes" the uterus by:
- Causing decidual necrosis (detaches the pregnancy)
- Softening the cervix
- Up-regulating prostaglandin receptors in the myometrium (making it MORE sensitive to misoprostol)
Then misoprostol delivers the "punch" — powerful uterine contractions to expel the products. The combination achieves > 95–98% complete abortion rates in the first trimester.
Key surgical methods [2]:
-
Manual Vacuum Aspiration (MVA) [2]
- Used up to ~12 weeks
- Uses a handheld syringe to create vacuum
- Can be performed under local anaesthesia (paracervical block)
- Advantage: no need for electricity, portable, quiet
-
Suction (Vacuum) Aspiration / Evacuation [2]
- The most commonly used surgical method for first-trimester TOP
- Procedure: Cervical dilation (mechanical dilators or osmotic dilators like laminaria) → insertion of suction cannula through cervix → vacuum applied to aspirate uterine contents → gentle sharp curettage may follow to ensure completeness
- Typically performed under general anaesthesia or conscious sedation
- Usually completed in 10–15 minutes
-
Dilation and Evacuation (D&E) [2]
- Used for second-trimester TOP (typically > 14 weeks)
- Requires more cervical dilation (often using osmotic dilators placed the day before, e.g., laminaria tents or Dilapan-S)
- Procedure: Cervical dilation → combination of suction, forceps (Sopher or Bierer), and curettage to evacuate the uterus
- Requires experienced operator
- Higher risk of complications than first-trimester procedures (haemorrhage, perforation, cervical laceration, retained products)
-
Hysterotomy [2]
- Essentially a mini-caesarean section
- Rarely used — reserved for failed medical/surgical TOP or when other methods are contraindicated
- Higher morbidity (it's a major abdominal operation)
- Creates a uterine scar → implications for future pregnancies (risk of uterine rupture)
Cervical Preparation/Priming — Why and How?
Why? The cervix in a pregnant woman (especially nulliparous) is relatively firm and closed. Attempting to dilate it rapidly and mechanically without preparation increases the risk of:
- Cervical laceration
- Uterine perforation
- Cervical incompetence in future pregnancies
How?
- Pharmacological: Misoprostol 400 μg vaginally 3h before, or Mifepristone 200 mg orally 24-48h before → softens and dilates cervix
- Mechanical (osmotic dilators):
- Laminaria tents: Dried seaweed sticks inserted into cervical canal → absorb moisture → swell gradually over 12–24h → gentle, progressive dilation
- Dilapan-S: Synthetic osmotic dilator, works similarly
Cervical priming is recommended for: [2]
- All women undergoing surgical TOP at > 12 weeks
- Nulliparous women at any gestation
- Women < 18 years
- WHO recommends cervical priming for ALL surgical TOPs to reduce complications
Clinical Features
Symptoms
These relate to the clinical presentation of women SEEKING TOP, and the expected/abnormal symptoms DURING and AFTER the procedure.
Women seeking TOP typically present with:
-
Confirmed pregnancy — positive urine/serum β-hCG
- Amenorrhoea (missed period) — due to maintained decidua under progesterone from the corpus luteum, then placenta
- Breast tenderness — due to rising oestrogen and progesterone
- Nausea/vomiting — due to rising β-hCG stimulating the chemoreceptor trigger zone
- Urinary frequency — due to enlarging uterus pressing on the bladder (early pregnancy)
-
Reason for seeking TOP — this is what the clinician must explore sensitively and document in relation to the legal grounds
Expected symptoms (these are the desired pharmacological effects):
| Symptom | Mechanism |
|---|---|
| Uterine cramping / abdominal pain | Misoprostol/prostaglandins cause myometrial contractions to expel the pregnancy — essentially labour-like pain |
| Vaginal bleeding | Decidual necrosis (mifepristone) + expulsion of gestational tissue → endometrial vessels exposed → bleeding. Usually heavier than a period, with clots. |
| Passage of products of conception | The intended outcome — the gestational sac, embryo/fetus, and decidual tissue are expelled |
| Nausea, vomiting, diarrhoea | Prostaglandin side effects — PGE1 acts on GI smooth muscle (stimulates peristalsis) and the vomiting centre. More common with sublingual/oral misoprostol |
| Fever, chills | Prostaglandin-mediated thermoregulatory effects (PGE1 affects the hypothalamic thermostat). Usually transient ( < 24h). If persistent → suspect infection |
Abnormal / Red flag symptoms (suggest complications):
| Symptom | Concern |
|---|---|
| Excessive heavy bleeding (soaking > 2 pads/hour for > 2 hours) | Incomplete abortion, uterine atony, retained products |
| Persistent severe pain not responding to analgesia | Uterine perforation, infection, ectopic pregnancy (if not excluded pre-procedure) |
| Fever > 38°C persisting > 24 hours post-misoprostol | Endometritis / sepsis |
| Foul-smelling vaginal discharge | Endometritis |
| No bleeding at all after medical TOP | Failed abortion — pregnancy may be continuing |
Expected symptoms:
| Symptom | Mechanism |
|---|---|
| Mild uterine cramping post-procedure | Normal myometrial contractions as the uterus involutes back toward pre-pregnancy size |
| Light-moderate vaginal bleeding for 1–2 weeks | Normal post-procedural bleeding as the endometrium heals. Like a period. |
Abnormal / Red flag symptoms:
| Symptom | Concern |
|---|---|
| Heavy vaginal bleeding (soaking > 2 pads/hr) | Uterine atony, retained products, perforation with intra-abdominal bleeding, cervical laceration |
| Severe abdominal pain | Perforation (especially if peritonitic features), haematometra (blood trapped in uterus due to cervical spasm — "post-abortal syndrome") |
| Fever | Endometritis / pelvic sepsis |
| No return of menses by 6 weeks post-procedure | Asherman syndrome (intrauterine adhesions), ongoing pregnancy (if incomplete evacuation) |
Signs
| Sign | Significance |
|---|---|
| Uterine size on bimanual examination | Correlate with dates — discrepancy may suggest wrong dates, multiple pregnancy, molar pregnancy, fibroids |
| Cervical assessment | Firmness, dilation, length — guides need for cervical priming |
| Adnexal tenderness / mass | May suggest ectopic pregnancy (must exclude before TOP) — ectopic is a contraindication to medical/surgical uterine TOP |
| Signs of infection (fever, cervical motion tenderness, purulent discharge) | Active PID → should be treated before or concurrently with TOP to reduce post-procedure sepsis risk |
| Sign | Significance |
|---|---|
| Ease of cervical dilation | Resistance → risk of cervical tear; too easy in a nullipara → may suggest cervical incompetence |
| Feel of the uterine cavity | "Gritty" sensation with curette against myometrium indicates complete evacuation; "smooth" may suggest need for more aspiration |
| Sudden loss of resistance / instruments passing further than expected | Uterine perforation — the most feared immediate surgical complication |
| Volume and character of aspirated tissue | Must confirm tissue is present (products of conception) — if absent, suspect ectopic pregnancy or complete abortion before procedure |
| Sign | Clinical Significance |
|---|---|
| Tachycardia, hypotension | Haemorrhage (may be concealed intra-abdominal if perforation), vasovagal reaction, or sepsis |
| Peritoneal signs (guarding, rigidity, rebound tenderness) | Uterine perforation with bowel injury, haemoperitoneum |
| Tender, bulky uterus | Retained products of conception or endometritis |
| Distended, tender uterus with closed cervical os | Haematometra (post-abortal syndrome) — blood trapped in the uterus because the cervix has clamped down. Treat with uterine re-evacuation. |
| Fever > 38°C | Endometritis / sepsis |
Pathophysiology of Key Processes
The entire process hinges on the hormonal maintenance of pregnancy:
After the pregnancy is removed (by either method), the placental bed is exposed — this is a raw, vascular surface where spiral arteries previously supplied the placenta. Haemostasis depends on:
- Myometrial contraction — the "living ligature" effect where the interlacing muscle fibres compress the blood vessels
- Coagulation cascade — forming clots at the vessel ends
- Endometrial regeneration — eventually, the endometrium regrows to cover the raw surface
If the uterus fails to contract (atony) or products are retained (preventing full contraction), bleeding continues.
- The uterine wall becomes thinner as the uterus expands
- Greater vascularity → more severe haemorrhage if perforated
- More dilation required → more force → more risk
- If bowel is drawn into the uterus through a perforation during suction → catastrophic bowel injury
Pre-procedure Assessment (Clinical Approach)
Before any TOP, the following must be established:
- Urine β-hCG (qualitative — confirms pregnancy)
- Transvaginal ultrasound (TVUS) — confirms:
- Intrauterine location (excludes ectopic — ectopic pregnancy is a contraindication to uterine TOP)
- Viability (fetal heartbeat)
- Gestational age (crown-rump length in first trimester)
- Number of fetuses
- Excludes molar pregnancy
- By last menstrual period (LMP) and confirmed by ultrasound
- This determines which method is appropriate and whether it falls within the legal limit
- History: medical conditions, allergies, medications, previous surgery (especially uterine surgery)
- Blood tests:
- FBC — baseline Hb (anaemia ↑ risk with any bleeding)
- Blood group and Rh status — Anti-D immunoglobulin must be given to Rh-negative women to prevent Rh isoimmunisation [2]
- Coagulation screen (if indicated)
- STI screening (Chlamydia, Gonorrhoea) — infection increases risk of post-TOP endometritis
- Non-directive counselling — presenting all options (continuing pregnancy, adoption, TOP) without bias
- Discussion of methods available, risks, and complications
- Psychological support and follow-up arrangements
- Contraception counselling — ideally, effective contraception should be started immediately post-TOP to prevent repeat unintended pregnancy [3]
- Written informed consent
- Two doctors must certify the legal grounds for TOP (Form A equivalent in HK practice) [2]
Must Exclude Before Proceeding with TOP
- Ectopic pregnancy — uterine evacuation will NOT treat an ectopic; the ectopic will continue to grow and may rupture, causing life-threatening haemorrhage
- Molar pregnancy — requires specific management (suction evacuation under ultrasound guidance + β-hCG monitoring for gestational trophoblastic neoplasia)
- Gestational age beyond legal limit (unless emergency grounds)
- Active pelvic infection — should be treated first or concurrent antibiotics given
Drugs Affecting Uterine Motility — Detailed Pharmacology
This section is derived from the lecture on "Drugs affecting uterine motility" [3].
Uterotonic Agents (Stimulate Uterine Contraction)
These are used for TOP, induction of labour, and management of PPH.
- Mechanism: Acts on oxytocin receptors (Gq-coupled) on myometrial cells → ↑ intracellular Ca²⁺ → uterine contraction [3]
- Sensitivity of the myometrium to oxytocin increases throughout pregnancy (due to increasing oxytocin receptor expression) — this is why oxytocin is more effective at term than early pregnancy [3]
- In TOP: Used as adjunct in second-trimester medical TOP; NOT effective as sole agent in first trimester (insufficient receptor expression)
- Routes: IV infusion (titrated)
- Side effects: Water retention (oxytocin has ADH-like activity at high doses → hyponatraemia → seizures if severe), uterine hyperstimulation, nausea, hypotension [3]
-
Misoprostol (PGE1 analogue) [3]:
- Acts on EP2/EP3 receptors on myometrium → ↑ intracellular Ca²⁺ → contraction
- Also causes cervical ripening by collagenase activation and glycosaminoglycan changes in the cervical stroma
- Cheap, stable at room temperature, multiple routes
- Side effects: Diarrhoea (GI smooth muscle stimulation), nausea, vomiting, fever/chills (hypothalamic effect), shivering
- Contraindications: Known allergy; caution in asthma (can cause bronchospasm — though PGE1 is less bronchoconstrictive than PGF2α) [3]
-
Gemeprost (PGE1 analogue) [3]:
- Vaginal pessary only
- Requires cold storage (-10 to -20°C)
- More expensive and less convenient than misoprostol
- Used mainly in second-trimester TOP
-
Dinoprostone (PGE2) [3]:
- Used more commonly for cervical ripening/induction of labour at term
- Vaginal gel or pessary (e.g., Propess — slow-release PGE2 insert)
- Less commonly used for TOP
-
Carboprost (15-methyl PGF2α, Hemabate) [3]:
- Primarily used for refractory PPH (not standard for TOP)
- Intramuscular injection
- Contraindicated in asthma (PGF2α causes bronchoconstriction — PGF2α constricts bronchial smooth muscle via FP receptors)
- Mechanism: Competitive antagonist at progesterone receptors [3]
- Also has anti-glucocorticoid activity (structurally related to cortisol — shares steroid backbone)
- Effect: Decidual necrosis, cervical softening, sensitization to prostaglandins
- Half-life: ~25–30 hours → allows single oral dose
- Not a prostaglandin itself — works synergistically WITH prostaglandins
- Side effects: Nausea, vomiting, heavy bleeding
These are NOT used for TOP (they are the opposite — used to STOP premature contractions), but understanding them helps you understand the pharmacology from first principles.
Included here for completeness as per the lecture [3]:
| Drug | Mechanism | Use |
|---|---|---|
| Atosiban | Oxytocin receptor antagonist | Preterm labour |
| Nifedipine | L-type calcium channel blocker → ↓ Ca²⁺ entry → ↓ contraction | Preterm labour (first-line in many protocols) |
| Ritodrine / Salbutamol | β2-agonist → ↑ cAMP → ↓ intracellular Ca²⁺ → relaxation | Preterm labour (less used due to side effects) |
| Magnesium sulphate | Competes with Ca²⁺ → ↓ contractility | Pre-eclampsia seizure prophylaxis; mild tocolytic effect |
| Indomethacin | COX inhibitor → ↓ prostaglandin synthesis | Short-term tocolysis ( < 32 weeks) |
| Progesterone | Maintains uterine quiescence | Prevention of preterm labour in high-risk women |
Drug Pharmacology — Exam Integration
Think of the myometrium as a "contraction machine" driven by intracellular calcium. Anything that increases Ca²⁺ (oxytocin, prostaglandins) → contraction. Anything that decreases Ca²⁺ (nifedipine, β2-agonists, MgSO₄) → relaxation. Mifepristone doesn't directly affect calcium but removes the "brake" (progesterone) that was keeping the uterus quiet, and it up-regulates prostaglandin receptors so the "accelerator" (misoprostol) works better.
From the Gynaecological Emergency lecture [4]:
TOP-related emergencies include [4]:
- Incomplete abortion — retained products of conception after attempted TOP → heavy bleeding, infection
- Septic abortion — infection complicating incomplete/complete abortion → fever, foul discharge, uterine tenderness, sepsis
- Uterine perforation — instrument passes through the uterine wall → risk of bowel injury, haemoperitoneum
- Haemorrhage — may be due to atony, retained products, cervical laceration, perforation
- Failed TOP — continuing pregnancy (especially with medical TOP — 2–5% failure rate requiring surgical completion)
Clinical approach to a woman presenting with heavy bleeding after TOP [4]:
- A-B-C-D-E assessment (resuscitate if haemodynamically unstable)
- IV access, bloods (FBC, group & save/crossmatch, coagulation)
- Pelvic ultrasound — retained products? Haematometra?
- Examination — cervical os open/closed? Products visible at os?
- If products at os → remove with sponge forceps
- If retained products on USS → surgical evacuation (suction curettage)
- Uterotonics (oxytocin, misoprostol) if uterine atony
- Antibiotics if signs of infection
All Rh-negative women undergoing TOP (medical or surgical) should receive anti-D immunoglobulin [2]:
- Why? Fetomaternal haemorrhage during TOP can expose the Rh-negative mother to Rh-positive fetal red cells → maternal immune system produces anti-D antibodies → these cross the placenta in future pregnancies and destroy Rh-positive fetal red cells → haemolytic disease of the fetus and newborn (HDFN)
- When? Within 72 hours of the procedure
- Dose:
- ≤ 12 weeks: 250 IU anti-D (some guidelines say not required < 12 weeks for medical TOP if no instrumentation — this is debated; RCOG 2024 suggests considering it from 10 weeks for surgical and all > 12 weeks)
- > 12 weeks: 500 IU anti-D + Kleihauer test to check if additional dose needed
Fertility returns rapidly after TOP (ovulation can occur within 2 weeks) [3], so contraception should be discussed and ideally initiated immediately:
| Method | When to Start |
|---|---|
| COCP / POP | Day of or day after the procedure |
| Depo-Provera injection | Day of procedure |
| Implant (e.g., Nexplanon) | Day of procedure |
| IUD/IUS | Can be inserted at the time of surgical TOP (immediately post-evacuation) or at the follow-up visit |
| Condoms | Immediately |
High Yield — Post-TOP Contraception
Immediate initiation of long-acting reversible contraception (LARC) — IUD/IUS or implant — at the time of surgical TOP significantly reduces repeat unintended pregnancy rates. This is a key public health intervention.
- The majority of women do NOT experience long-term psychological harm after TOP [1]
- Risk factors for psychological distress post-TOP: pre-existing mental health conditions, ambivalence about the decision, lack of social support, later gestational age, TOP for fetal anomaly (particularly distressing as the pregnancy was often wanted)
- Myth: "Post-abortion syndrome" — this is NOT a recognized psychiatric diagnosis. Large systematic reviews show that the best predictor of mental health after TOP is mental health BEFORE TOP.
- Supportive, non-judgmental counselling before and after the procedure is essential [2]
High Yield Summary
Definition: TOP = deliberate ending of pregnancy before viability; legal in HK under Cap. 212 with specific conditions.
Legal Requirements (HK):
- ≤ 24 weeks; 2 doctors' opinions; approved institution; specified grounds (maternal health, fetal anomaly)
- No gestational limit if immediately necessary for maternal life/grave permanent injury
Methods:
- Medical: Mifepristone (anti-progestogen) + Misoprostol (PGE1 analogue) — works by decidual necrosis + uterine contractions
- Surgical: Vacuum aspiration (1st trimester), D&E (2nd trimester); cervical priming recommended
Key Pharmacology:
- Mifepristone → blocks progesterone → decidual necrosis, cervical softening, sensitizes myometrium to prostaglandins
- Misoprostol → PGE1 agonist → uterine contractions + cervical ripening
- Gemeprost → PGE1 (vaginal, needs cold storage)
- Oxytocin → adjunct in 2nd trimester
Pre-procedure Must-Dos:
- Confirm IUP (exclude ectopic!)
- Gestational age (USS)
- Blood group + Rh status (anti-D if Rh-negative)
- STI screening
- Counselling + consent (2 doctors)
Key Complications: Haemorrhage, incomplete abortion, uterine perforation, infection/sepsis, cervical laceration, failed TOP, Asherman syndrome
Post-TOP: Start contraception immediately; follow-up to confirm complete evacuation
Active Recall - Termination of Pregnancy
[1] WHO guidelines on safe abortion (2022 update); Ryan Ho GI (hepatic adenoma section re: OCP association as contextual reference) [2] Lecture slides: GCBC-OG-Gyn Emergency_Notes to students_Sep2024.pdf; Block C - Gyanecological Emergency Notes to Students.pdf; OBGYN Clinical Test By Topic.pdf [3] Lecture slides: Block C - The woman needs that drug_ Oral contraceptives, Drugs affecting uterine motility.pdf [4] Lecture slides: GCBC-OG-Gyn Emergency_Notes to students_Sep2024.pdf; Block C - Gyanecological Emergency Notes to Students.pdf [5] Senior notes: Ryan Ho Radiology.pdf (Obstetric imaging section) [6] Senior notes: Maksim Surgery Notes.pdf (Haemoperitoneum / ectopic pregnancy context) [7] Senior notes: Ryan Ho Respiratory.pdf (VTE risk factors including OCP)
Differential Diagnosis of Termination of Pregnancy
The differential diagnosis (DDx) for TOP is a somewhat unusual framing compared to a typical "disease" DDx. In clinical practice, the DDx operates at two distinct levels:
- Before TOP: When a woman presents requesting TOP or with a positive pregnancy test and symptoms — you must confirm the nature and location of the pregnancy and exclude conditions that mimic normal intrauterine pregnancy or that contraindicate standard TOP.
- After TOP: When a woman presents with complications post-TOP (bleeding, pain, fever) — you must differentiate between TOP-related complications and other gynaecological/surgical emergencies.
Let's work through both systematically, because the exam scenario is almost always a case vignette — either a woman presenting with early pregnancy symptoms (and you must formulate a prioritised DDx list) or a woman presenting post-procedure with a complication.
The Lecture's Core Teaching Point
"The most important part in this session is the ability to formulate the list of differential diagnoses and to prioritize them according to the clinical condition and NOT just to give the right diagnosis." [2][4]
This tells you the examiners want you to think broadly and systematically, not jump to a single answer.
Level 1: DDx Before TOP — "Is This Really a Normal Intrauterine Pregnancy?"
Before performing TOP, you must confirm that what you are dealing with is a viable intrauterine pregnancy (IUP). If it is NOT a normal IUP, proceeding with standard TOP is either inappropriate, dangerous, or both.
| Condition | Why It Matters | How to Differentiate |
|---|---|---|
| Ectopic pregnancy | Uterine evacuation will NOT treat an ectopic — the ectopic continues to grow and may rupture, causing life-threatening haemorrhage [2][4] | TVUS shows empty uterus or no definite IUP; adnexal mass/bagel sign; β-hCG does not correlate with empty uterus; cervical excitation |
| Gestational trophoblastic disease (molar pregnancy) | GTD is an important differential diagnosis of threatened miscarriage [5]; requires specific management (suction evacuation + β-hCG monitoring for GTN, NOT standard medical TOP) | USS: "snowstorm" appearance (complete mole), abnormally large uterus for dates, markedly elevated β-hCG ( > 100,000), theca lutein cysts |
| Spontaneous miscarriage (in progress) | If the pregnancy is already non-viable or being expelled, the management pathway differs (expectant vs medical vs surgical for miscarriage, not "TOP") | USS: absent fetal heartbeat, collapsed gestational sac, products in cervical canal; clinical: open cervical os, bleeding with clots |
| Pregnancy of unknown location (PUL) | Positive β-hCG but nothing seen on USS — could be very early IUP, ectopic, or recent complete miscarriage | Serial β-hCG (48h apart) + repeat USS; do NOT proceed with TOP until location confirmed |
| Heterotopic pregnancy | Coexistence of IUP + ectopic pregnancy; rare spontaneously (~1:30,000) but much more common after assisted reproduction (1:100) | Even after confirming IUP on USS, maintain vigilance for adnexal pathology especially in IVF patients |
| Cornual/interstitial pregnancy | Failure to obtain tissue at suction termination of what appears, ultrasonically, to be an intrauterine pregnancy suggests an abnormal site of implantation, including cornual pregnancy [2][4] | USS: eccentrically located gestational sac, thin myometrial mantle ( < 5 mm), "interstitial line sign" |
Why Is Ectopic Pregnancy the #1 DDx to Exclude?
It is essential that clinicians consider the diagnosis of ectopic pregnancy in any woman of reproductive age who complains of abdominal pain or fainting attack secondary to hypovolaemic shock. [2][4]
β-hCG testing should be considered in any young woman with unexplained abdominal pain whether she has missed a period or had abnormal vaginal bleeding. [2][4]
An ultrasonically "empty" uterus in a woman who presents with vaginal bleeding in pregnancy may indicate an ectopic pregnancy. [2][4]
If you perform uterine evacuation thinking you are terminating an IUP, but the pregnancy is actually ectopic → no tissue obtained → ectopic persists → patient goes home → ectopic ruptures → haemoperitoneum → potentially fatal. This is a classic medicolegal scenario.
Ectopic pregnancy presents with the classic triad of missed period, vaginal bleeding, and abdominal pain [5]. However, clinical diagnosis can only be made in half of the patients [5] — meaning the other half present atypically.
- Gastrointestinal symptoms may be prominent in ectopic pregnancy, notably diarrhoea and painful defecation — because blood in the pouch of Douglas irritates the rectum
- Syncope or shoulder pain [5] — shoulder tip pain is referred pain from diaphragmatic irritation by haemoperitoneum (C3-5 phrenic nerve dermatome)
- Abdominal tenderness with varying degree of peritonism; cervical excitation [5]
Risk factors for ectopic [5]:
- Previous ectopic pregnancy
- Tubal damage from infection/surgery
- History of infertility
- Assisted reproduction techniques
- Increased age
- Smoking
USS features suggestive of ectopic pregnancy [5]:
- "Bagel sign" — a hyperechoic ring (the gestational sac with trophoblast) in the adnexa
- Complex, inhomogeneous adnexal mass separate from the ovary
- Empty uterus or pseudo-sac (a pseudo-sac is fluid collecting in the endometrial cavity due to decidual reaction — it lacks the double decidual sign of a true gestational sac)
- Moderate to large amount of free fluid in POD suggestive of haemoperitoneum [5]
GTD is an important differential diagnosis of threatened miscarriage [5] and can also present as an apparently normal early pregnancy requesting TOP. It encompasses:
| Type | Key Features |
|---|---|
| Complete hydatidiform mole | No fetal parts; 46,XX (all paternal); "snowstorm" on USS; very high β-hCG; large-for-dates uterus; theca lutein cysts; risk of hyperemesis gravidarum due to markedly elevated hCG [6] |
| Partial hydatidiform mole | Some fetal parts present (often triploid, e.g., 69,XXY); less dramatically elevated β-hCG; small-for-dates uterus |
| GTN (choriocarcinoma, invasive mole, PSTT) | May follow any type of pregnancy; persistently elevated/rising β-hCG after evacuation |
Why it matters for TOP DDx: If a molar pregnancy is managed as a standard medical TOP (mifepristone + misoprostol), there is risk of:
- Incomplete evacuation (molar tissue is bulky and may not pass completely)
- Missing the diagnosis → no β-hCG follow-up → GTN develops undetected
- The standard approach for molar pregnancy is suction evacuation (NOT medical) + histological examination of products + serial β-hCG monitoring
Level 2: DDx in the Woman Presenting with Early Pregnancy Symptoms
This is the more common exam scenario: a young woman (e.g., 25 years old) presents with abdominal pain and vaginal spotting [2][4]. You must think through the full DDx.
The approach is systematic — think obstetric/gynaecological first, then non-gynaecological.
| Condition | Key Differentiating Features |
|---|---|
| Threatened miscarriage | Viable IUP on USS + vaginal bleeding + closed cervical os; pain usually mild |
| Inevitable miscarriage | Open cervical os + bleeding + pain; USS may show low gestational sac |
| Incomplete miscarriage | Some products passed, some retained; open os; ongoing bleeding |
| Complete miscarriage | All products passed; os closing; bleeding settling; empty uterus on USS |
| Missed miscarriage | Non-viable IUP on USS (absent heartbeat, or embryo ≥ 7 mm with no heartbeat); minimal symptoms |
| Ectopic pregnancy | As above — the must-not-miss |
| Molar pregnancy | As above |
| Septic abortion | Infection complicating any type of miscarriage or post-TOP; fever, foul discharge, uterine tenderness |
These conditions can mimic early pregnancy symptoms or coexist with pregnancy.
| Condition | Key Differentiating Features |
|---|---|
| Ovarian cyst complications (torsion, rupture, haemorrhage) [7][8] | Sudden onset unilateral pain; USS shows ovarian cyst/mass; negative pregnancy test (unless coincidental pregnancy); torsion: waves of nausea/vomiting [7]; rupture: often during strenuous activity [7] |
| Pelvic inflammatory disease (PID) [7][8] | Lower abdominal pain (lower than appendicitis), usually bilateral, exacerbated by coitus (dyspareunia); vaginal discharge; cervical excitation; adnexal tenderness [7]; fever; elevated WCC/CRP |
| Endometriosis | Cyclical pain, dysmenorrhoea, dyspareunia; chronic history |
| Mittelschmerz [7] | Mid-cycle lower abdominal/pelvic pain due to rupture of follicular cyst and bleeding irritating the peritoneum — self-limiting; correlates with mid-cycle timing |
| Fibroid degeneration | Known fibroids; pain over the fibroid; red degeneration in pregnancy |
These are important because they can be misdiagnosed as a gynaecological emergency (and vice versa).
| Condition | Key Differentiating Features |
|---|---|
| Acute appendicitis [7][8] | RIF pain with migration from periumbilical area; anorexia, nausea; McBurney's point tenderness; Rovsing's sign; negative pregnancy test |
| Urinary tract infection / pyelonephritis [7] | Dysuria, frequency, urgency; loin tenderness and high fever ( > 39°C) in pyelonephritis; pyuria on urinalysis |
| Ureteric colic [7] | Colicky loin-to-groin pain that waxes and wanes; haematuria on dipstick; restless patient |
| Acute gastroenteritis | Diarrhoea, vomiting predominant; diffuse abdominal pain |
| DKA [8][9] | Life-threatening medical cause of acute abdomen; polyuria, polydipsia, Kussmaul breathing, ketotic breath; check Hstix |
| Acute MI [8][9] | Rare in young women but consider in older patients; epigastric pain can mimic GI/GYN cause; ECG essential |
The 'Always Check a Pregnancy Test' Rule
In girls presenting with acute abdominal pain: always ask LMP, order pregnancy test and USS abdomen. Do NOT perform PV examination on your own — consult Gynae. [8]
This is a fundamental principle — any woman of reproductive age with abdominal pain should have a pregnancy test. Ectopic pregnancy kills through missed diagnosis.
Level 3: DDx After TOP — "This Post-TOP Patient Is Unwell"
When a woman presents with complications after TOP, you must differentiate between:
| Complication | Presentation | Mechanism |
|---|---|---|
| Incomplete abortion / retained products | Ongoing heavy bleeding, cramping, open os; USS shows echogenic material in uterus | Failure to completely evacuate — retained trophoblastic/decidual tissue prevents full myometrial contraction |
| Uterine perforation | During or after procedure: sudden pain, hypotension, peritoneal signs; may present late with peritonitis if bowel injured | Instrument passes through myometrium; risk increased by retroverted uterus, advanced gestation, inexperience |
| Septic abortion / endometritis | Fever, foul vaginal discharge, uterine tenderness, tachycardia; may progress to septic shock | Ascending infection from lower genital tract into the endometrium facilitated by instrumentation and retained products (which serve as a nidus for infection) |
| Haematometra | Severe cramping pain post-procedure, tender distended uterus, CLOSED os, minimal external bleeding | Cervix clamps down after procedure, trapping blood inside the uterus |
| Cervical laceration | Visible tear on speculum; may bleed significantly | Forceful dilation, especially without adequate cervical priming |
| Failed TOP (continuing pregnancy) | No or minimal bleeding after medical TOP; persistent pregnancy symptoms; USS shows viable IUP | Medical TOP has 2-5% failure rate; always confirm completion |
| Asherman syndrome | Late complication — secondary amenorrhoea weeks to months after TOP | Excessive curettage damages the basalis layer of endometrium → intrauterine adhesion formation [9] |
| Condition | Why It Mimics | How to Differentiate |
|---|---|---|
| Ectopic pregnancy (missed pre-TOP) | Pain, bleeding, collapse — but the ectopic was never treated | No products of conception obtained at evacuation; persistent/rising β-hCG; USS shows adnexal mass |
| Ovarian pathology | Post-TOP pain and bleeding overlap with ovarian cyst torsion/rupture | USS differentiates — look for adnexal mass separate from uterus |
| PID / tubo-ovarian abscess | Fever, pain — overlaps with post-TOP endometritis | Bilateral adnexal tenderness, purulent discharge, may have history of STI |
| Appendicitis | RIF pain post-procedure can be attributed to TOP when it's actually appendicitis | Classical migratory pain; RIF tenderness higher than pelvic pathology; no uterine tenderness |
This flowchart captures the clinical reasoning for the pre-TOP DDx:
The lecture emphasises prioritising differentials according to the clinical condition [2][4]. The hierarchy should be:
- Life-threatening conditions FIRST: Ruptured ectopic pregnancy, septic abortion, uterine perforation with bowel injury, DKA, acute MI
- Urgent but not immediately life-threatening: Unruptured ectopic, ovarian torsion, incomplete miscarriage with heavy bleeding, molar pregnancy
- Important but less urgent: PID, threatened miscarriage, UTI, ureteric colic
- Benign / self-limiting: Mittelschmerz, complete miscarriage, GE
Clinical Pearl — The 'No Products' Red Flag
Failure to obtain tissue at suction termination of what appears, ultrasonically, to be an intrauterine pregnancy suggests an abnormal site of implantation, including cornual pregnancy. [2][4]
This is a critical safety net. After any surgical TOP, the aspirated tissue MUST be inspected. If no products of conception (villi) are identified:
- Consider ectopic pregnancy (the IUP was actually a pseudo-sac)
- Consider cornual/interstitial pregnancy (implanted in the cornua, not accessible to the suction cannula)
- The patient needs urgent further evaluation — do NOT discharge home.
| Category | Condition | Key Clue |
|---|---|---|
| Must exclude pre-TOP | Ectopic pregnancy | Empty uterus + positive β-hCG + adnexal mass |
| Molar pregnancy | "Snowstorm" USS, very high β-hCG, large-for-dates | |
| Cornual pregnancy | Eccentric sac, thin myometrium, no products at evacuation | |
| Heterotopic pregnancy | IVF patient with IUP + persistent adnexal symptoms | |
| Pregnancy-related DDx | Threatened miscarriage | Viable IUP + bleeding + closed os |
| Inevitable miscarriage | Open os + bleeding | |
| Incomplete miscarriage | Retained products + open os | |
| Missed miscarriage | Non-viable IUP + absent heartbeat | |
| Septic abortion | Fever + tenderness + infected products | |
| Gynae non-pregnancy | Ovarian cyst torsion/rupture | Unilateral; USS shows cyst; pregnancy test negative |
| PID | Bilateral lower abdominal pain, discharge, cervical excitation | |
| Mittelschmerz | Mid-cycle, self-limiting | |
| Non-gynae | Appendicitis | Migratory pain, RIF, anorexia |
| Ureteric colic | Colicky loin-to-groin, haematuria | |
| UTI/pyelonephritis | Dysuria, frequency, loin tenderness | |
| DKA | Polyuria, Kussmaul breathing, high glucose | |
| Post-TOP complications | Incomplete abortion | Ongoing bleeding + retained products on USS |
| Uterine perforation | Sudden pain, peritonism, instrument too deep | |
| Endometritis/sepsis | Fever, foul discharge, tender uterus | |
| Haematometra | Pain, distended uterus, closed os, minimal external bleeding | |
| Failed TOP | Persistent pregnancy symptoms, viable IUP on USS | |
| Asherman syndrome | Secondary amenorrhoea weeks-months later |
High Yield Summary
Pre-TOP DDx — The 3 Must-Excludes:
- Ectopic pregnancy — empty uterus + positive β-hCG; treat with laparoscopic salpingectomy, NOT uterine evacuation
- Molar pregnancy — snowstorm USS, very high β-hCG; requires suction evacuation + β-hCG surveillance, NOT standard medical TOP
- Cornual/interstitial pregnancy — eccentric sac; suspected if no products obtained at suction TOP
Key Principles:
- Always perform pregnancy test in any reproductive-age woman with abdominal pain
- Always perform TVUS before TOP to confirm IUP, exclude ectopic, date pregnancy
- Always inspect evacuated tissue for products of conception — absence suggests abnormal implantation site
- After TOP, differentiate complications (incomplete abortion, perforation, sepsis, haematometra, failed TOP) from non-TOP causes (ectopic, appendicitis, PID, ovarian pathology)
- Prioritise life-threatening conditions (ruptured ectopic, septic abortion, perforation) over less urgent diagnoses
Active Recall - DDx of Termination of Pregnancy
References
[2] Lecture slides: GCBC-OG-Gyn Emergency_Notes to students_Sep2024.pdf; Block C - Gyanecological Emergency Notes to Students.pdf [4] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf [5] Lecture slides: GC 223. Complications of Early Pregnancy.pdf [6] Senior notes: Maksim Medicine Notes.pdf (Gestational thyrotoxicosis section — hCG and molar pregnancy) [7] Senior notes: Ryan Ho GI.pdf (Appendicitis DDx section — gynaecological differentials) [8] Senior notes: Maksim Surgery Notes.pdf (Acute abdomen DDx; Paediatric surgical abdomen) [9] Senior notes: Maksim Medicine Notes.pdf (Secondary amenorrhoea — Asherman syndrome)
Diagnostic Criteria, Algorithm, and Investigations for Termination of Pregnancy
Unlike many medical conditions, TOP does not have "diagnostic criteria" in the traditional sense (e.g., there is no set of criteria to diagnose "TOP" the way you diagnose SLE or rheumatic fever). Instead, the diagnostic workup for TOP serves three interlocking purposes:
- Confirming the diagnosis of intrauterine pregnancy — is there a pregnancy, where is it, and is it viable?
- Establishing gestational age — this determines the method of TOP and legality
- Assessing maternal fitness — are there conditions that would affect the safety of the procedure?
Think of the diagnostic process as building a pre-operative assessment — you are confirming that what you plan to treat is actually what you think it is, and that the patient is safe to undergo the procedure.
Diagnostic Criteria — What Must Be Confirmed Before TOP
There are no formal "diagnostic criteria" published by ILAE-type bodies, but in practice every reputable guideline (WHO, RCOG, NICE, Hong Kong HA protocols) requires the following to be established:
Ideally, all women should undergo ultrasound examination before termination of pregnancy to establish gestational age, viability, and site [2][4].
Why? Because if the pregnancy is not intrauterine, proceeding with uterine TOP is:
- Futile (you won't treat the actual pregnancy)
- Dangerous (ectopic persists and may rupture)
- Misleading (false reassurance that the pregnancy has been terminated)
How is IUP confirmed?
| Modality | What It Shows | When Visible |
|---|---|---|
| Urine β-hCG | Qualitative — confirms pregnancy exists | From ~implantation (about 6 days post-conception; practically from time of missed period) |
| Serum β-hCG | Quantitative — level helps interpret USS findings and track progress | Detectable ~10-12 days post-conception |
| Transvaginal ultrasound (TVUS) [10] | Gestational sac visible by 5 weeks; yolk sac by 6 weeks (definite IUP); cardiac activity with embryo by 6-7 weeks | Correlates with serum β-hCG level — see discriminatory zone below |
The Discriminatory Zone concept:
This is a critical concept linking serum β-hCG to expected USS findings.
- The discriminatory zone is the serum β-hCG level above which a gestational sac should be visible on TVUS if an IUP is present
- Traditionally quoted as 1,000–1,500 mIU/mL for TVUS (some centres use 2,000)
- If serum β-hCG is above the discriminatory zone and NO IUP is seen on TVUS → strongly suspect:
- Ectopic pregnancy
- Recent complete miscarriage
- Very rarely, early multiple pregnancy or technical factors (obesity, fibroids, retroverted uterus)
The HKU Study on Discriminatory Levels
A study from Queen Mary Hospital, HKU (Ko & Cheung) reviewed 113 patients with pregnancy of unknown location and β-hCG levels > 1,000 mIU/mL [5]. Key findings:
- 20.4% (23/113) subsequently had viable intrauterine pregnancies
- The highest β-hCG associated with a subsequent normal IUP was 9,083 mIU/mL (in a triplet pregnancy)
- Possible factors for non-visualisation included uterine fibroids, adenomyosis, endometrial polyps, and high BMI
- Conclusion: Viable intrauterine pregnancy is possible even with β-hCG above the traditional discriminatory zone. Management should NOT be based solely on a single β-hCG level in haemodynamically stable patients [5].
This is directly relevant to TOP: you should NOT assume "empty uterus = ectopic" just because β-hCG is above the discriminatory zone. Serial β-hCG + repeat USS is the safe approach in stable patients.
Gestational age must be determined to confirm the pregnancy falls within the legal limit (≤ 24 weeks in Hong Kong) and to select the appropriate TOP method [2][4].
Methods of dating:
| Method | How It Works | Accuracy |
|---|---|---|
| Last menstrual period (LMP) | Naegele's rule: EDD = LMP + 7 days − 3 months + 1 year; assumes 28-day cycle with ovulation at day 14 | ± 2 weeks (unreliable if irregular cycles, recent OCP use, breastfeeding, uncertain dates) |
| Crown-rump length (CRL) on USS [10] | Measured from top of fetal head to rump; most accurate dating parameter in first trimester (up to 13+6 weeks) | ± 3-5 days (this is WHY first-trimester USS dating is preferred) |
| Biparietal diameter (BPD), femur length (FL), abdominal circumference (AC) [10] | Used for second-trimester dating if CRL not available | ± 1-2 weeks (less accurate than CRL) |
Why does gestational age matter so much?
- Determines legality (≤ 24 weeks for standard grounds in HK)
- Determines method: medical vs surgical, first-trimester vs second-trimester protocol
- Determines risk: later gestation = higher complication rates
- Determines cervical preparation: more needed at later gestations
This is the pre-procedural assessment — confirming the woman can safely undergo medical or surgical TOP. Detailed investigations are outlined below.
The following algorithm outlines the step-by-step approach from the moment a woman presents seeking TOP or is referred for TOP:
Investigation Modalities — Detailed Breakdown
Let's now go through each investigation systematically, explaining what it is, why we do it, key findings, and interpretation — from first principles.
What it is: A qualitative immunoassay detecting the β-subunit of human chorionic gonadotropin (hCG) in urine.
Why the β-subunit? Because the α-subunit of hCG is shared with TSH, LH, and FSH [6]. Testing the β-subunit ensures specificity for hCG (i.e., pregnancy).
Why we do it:
- A negative pregnancy test effectively rules out ectopic pregnancy [5] — this simple bedside test is the most important initial investigation
- Confirms the basic premise (is there a pregnancy at all?)
Key findings and interpretation:
| Result | Interpretation |
|---|---|
| Positive | Pregnancy present (could be IUP, ectopic, molar, or failing/recent) → proceed to USS |
| Negative | No pregnancy → stop the TOP pathway; explore other causes |
| Faintly positive | Very early pregnancy or very low β-hCG → confirm with serum β-hCG |
Sensitivity: Modern urine tests detect β-hCG ≥ 20–25 mIU/mL → positive from approximately the day of the expected period.
Pitfall: A very recently completed miscarriage may still show positive β-hCG (takes 1-2 weeks to clear). Also, extremely high β-hCG (e.g., molar pregnancy) can cause a false negative due to the "hook effect" — excess antigen saturates both the capture and detection antibodies, preventing sandwich formation. If clinical suspicion is high, always confirm with serum β-hCG.
What it is: A quantitative blood test measuring the exact level of β-hCG in mIU/mL.
Why we do it:
- Correlates with gestational age and expected USS findings (discriminatory zone)
- Serial measurements (48-hour trend) help distinguish viable IUP, ectopic, and failing pregnancy
- hCG assay is a key investigation for suspected ectopic pregnancy [5]
Key findings and interpretation:
| Scenario | β-hCG Trend (48h) | Interpretation |
|---|---|---|
| Normal early IUP | Rises ≥ 66% in 48h (doubling time ~48h) | Reassuring; repeat USS when above discriminatory zone |
| Ectopic / abnormal pregnancy | Rises < 66% in 48h, or plateaus | Abnormal pregnancy — likely ectopic or failing IUP |
| Completing miscarriage | Falls > 50% in 48h | Pregnancy likely failing/resolving on its own |
| Molar pregnancy | Very high level ( > 100,000 mIU/mL) | Suspect complete mole; confirm with USS |
Discriminatory zone (for TVUS):
- 1,000–2,000 mIU/mL: Above this, a gestational sac should be visible on TVUS if it is an IUP
- But remember the HKU study: viable IUP was found with β-hCG up to 9,083 mIU/mL where no IUP was initially seen — so do NOT make irreversible decisions based on a single β-hCG level in stable patients [5]
Serial β-hCG — The 48-Hour Rule
Never rely on a single β-hCG value. The trend over 48 hours is far more informative:
- Normal doubling → likely viable IUP
- Suboptimal rise → ectopic or failing pregnancy
- Falling → miscarriage (spontaneous resolution)
Only act on a single value if the patient is haemodynamically unstable (e.g., ruptured ectopic → straight to theatre).
What it is: High-frequency ultrasound probe placed in the vagina, providing close proximity to the uterus and adnexa → superior resolution compared to transabdominal USS for early pregnancy assessment.
Why we do it: To establish gestational age, viability, and site of the pregnancy [2][4].
Signs of intrauterine pregnancy on TVUS [10]:
| Landmark | When Visible | Significance |
|---|---|---|
| Gestational sac | ~5 weeks (β-hCG ~1,000–2,000) | Earliest sign; look for double decidual sign (echogenic rim of decidua) to distinguish from pseudo-sac |
| Yolk sac | ~6 weeks | Definite confirmation of IUP (a pseudo-sac will NOT have a yolk sac) |
| Embryo with cardiac activity | ~6-7 weeks (CRL ~2-5 mm) | Confirms viability |
| Crown-rump length measurement | From ~6 weeks onward | Most accurate first-trimester dating (±3-5 days) |
Features suggestive of ectopic pregnancy on TVUS [5]:
| Finding | Description |
|---|---|
| "Bagel sign" | Hyperechoic ring in the adnexa representing ectopic gestational sac with surrounding trophoblast |
| Complex inhomogeneous adnexal mass | Moves separately from the ovary |
| Empty uterus or pseudo-sac | No yolk sac, no double decidual sign |
| Free fluid in pouch of Douglas | Suggests haemoperitoneum from tubal bleeding/rupture |
Features of molar pregnancy:
- "Snowstorm" or "cluster of grapes" appearance — multiple cystic spaces within the uterine cavity
- Uterus larger than expected for dates
- May have bilateral theca lutein cysts (from hCG hyperstimulation of the ovaries)
- No fetal parts in complete mole; some fetal parts in partial mole
Features of miscarriage:
| Type | USS Finding |
|---|---|
| Threatened | Viable IUP (FH present), ± subchorionic haematoma |
| Inevitable | Low-lying gestational sac, open internal os |
| Incomplete | Retained products (echogenic material > 15 mm AP diameter in uterine cavity) |
| Complete | Empty uterus, thin endometrium |
| Missed | Embryo ≥ 7 mm with no heartbeat, OR gestational sac ≥ 25 mm with no embryo |
RCOG/NICE Criteria for Diagnosing Miscarriage on USS (2023)
To avoid incorrectly diagnosing miscarriage (and thus potentially terminating a viable pregnancy), strict cut-offs apply:
- CRL ≥ 7 mm with no heartbeat → diagnose missed miscarriage (BUT recommend repeat scan in 7-14 days if any doubt)
- Mean gestational sac diameter ≥ 25 mm with no embryo → diagnose anembryonic pregnancy
- If measurements fall below these thresholds → inconclusive → MUST repeat scan in ≥ 7 days before concluding non-viability
This is safety-critical: misdiagnosing a viable early pregnancy as a missed miscarriage and proceeding to evacuation would effectively terminate a wanted pregnancy.
Why: Hb level establishes baseline [5] — essential because:
- Existing anaemia increases risk from any bleeding
- Provides comparison if post-procedure haemorrhage occurs
- Also note MCV [5] — microcytosis may suggest pre-existing iron deficiency (chronic blood loss, dietary insufficiency, thalassaemia trait — especially relevant in Hong Kong)
| Parameter | What to Look For | Clinical Relevance |
|---|---|---|
| Hb | Baseline; low Hb ( < 100 g/L) → optimise before elective TOP if possible | If Hb very low, may need iron supplementation or blood transfusion pre-procedure |
| MCV | Low → iron deficiency or thalassaemia trait | Hong Kong: thalassaemia carrier rate ~8.5%; microcytosis on FBC prompts Hb electrophoresis |
| WBC | Elevated → infection (PID, septic abortion) | Active infection should be treated before or concurrent with TOP |
| Platelets | Low → coagulopathy, ITP, DIC | Thrombocytopenia → increased bleeding risk |
Rh factor must be checked [5].
Why? Rh-negative women exposed to Rh-positive fetal red cells during TOP develop anti-D antibodies → these persist and cause haemolytic disease of the fetus and newborn (HDFN) in future Rh-positive pregnancies.
| Result | Action |
|---|---|
| Rh-positive | No anti-D needed |
| Rh-negative | Anti-D immunoglobulin must be administered within 72 hours of the procedure |
| Rh-negative, > 12 weeks gestation | Higher dose anti-D (500 IU) + Kleihauer-Betke test to quantify fetomaternal haemorrhage and determine if additional doses needed |
Rh-negative prevalence in Hong Kong: ~0.3-0.5% (much lower than Caucasian populations ~15%) — but when it does occur, the consequences of missed anti-D prophylaxis are devastating.
Why: In case haemorrhage occurs during or after the procedure, compatible blood must be available.
| Clinical Scenario | Recommendation |
|---|---|
| First-trimester surgical TOP (low risk) | Group and save (hold serum in blood bank) |
| Second-trimester TOP or high-risk patients | Crossmatch 2 units packed red cells |
| Known placenta praevia, fibroids, coagulopathy | Crossmatch + alert blood bank for potential massive transfusion |
When indicated:
- History of bleeding disorder
- Anticoagulant use
- Liver disease
- Septic abortion (risk of DIC — septic abortion is a known cause of obstetric DIC [11])
- Second-trimester TOP (higher bleeding risk)
Not routine for straightforward first-trimester TOP in an otherwise healthy woman.
Why: Ascending infection from untreated cervical/vaginal STIs during instrumentation → endometritis → pelvic sepsis → tubal damage → future fertility consequences.
| Pathogen | Test | Rationale |
|---|---|---|
| Chlamydia trachomatis | NAAT (nucleic acid amplification test) from endocervical/vaginal swab | Most common bacterial STI; often asymptomatic; major cause of post-abortal PID |
| Neisseria gonorrhoeae | NAAT + culture (for sensitivity) | Less common but more aggressive; causes acute PID |
Two approaches:
- "Screen and treat" — test all women; treat those who test positive (delays procedure)
- "Prophylactic antibiotics for all" — give empiric antibiotics (e.g., azithromycin 1g PO or doxycycline 100mg BD x 7 days) to all women undergoing surgical TOP regardless of screening results
Most guidelines (including RCOG) recommend either universal screening or universal prophylactic antibiotics. In practice, many centres provide prophylactic antibiotics to all.
Not routinely required before TOP. However, if the woman is overdue for cervical screening, it may be opportunistically performed. Not part of the standard pre-TOP workup.
| Investigation | Indication | Key Findings |
|---|---|---|
| Thyroid function (TSH, anti-TPO) [5] | Recurrent miscarriage workup (not routine for first TOP, but relevant if history of recurrent pregnancy loss) | Hypothyroidism / thyroid autoimmunity associated with miscarriage |
| Antiphospholipid antibodies [5][12] | Recurrent miscarriage (≥ 3 consecutive < 10 weeks, or ≥ 1 unexplained death > 10 weeks) | Lupus anticoagulant, anticardiolipin Ab, anti-β2-glycoprotein I Ab — must be positive on ≥ 2 occasions ≥ 12 weeks apart [12] |
| Karyotyping [5] | Recurrent miscarriage; suspected fetal chromosomal abnormality | Products of conception sent for karyotype; parental karyotyping if recurrent |
| Screening for uterine malformations [5] | Recurrent miscarriage (esp. second-trimester losses) | MRI pelvis or 3D-USS to identify septate, bicornuate, unicornuate uterus |
| Thrombophilia screen [5] | Recurrent second-trimester miscarriage | Protein C/S deficiency, antithrombin III deficiency, Factor V Leiden, prothrombin gene mutation |
| Tissue histology [5] | All surgical TOP specimens should be sent for histological examination | Confirm chorionic villi (products of conception present) — absence suggests ectopic or cornual pregnancy. Also identifies molar tissue (hydropic villi, trophoblastic proliferation) |
Histology of Evacuated Products — A Safety Net
Tissue mass obtained from evacuation should always be sent for histology: look for decidua, chorionic villi, and fetal parts [5].
- Chorionic villi present → confirms intrauterine pregnancy was evacuated → complete
- Decidua only, no villi → the "no products" scenario → suggests abnormal implantation site (ectopic, cornual) or complete miscarriage prior to procedure [2][4]
- Hydropic villi with trophoblastic proliferation → molar pregnancy → requires GTD surveillance
- Fetal parts → confirms presence of a fetus (relevant for later gestations)
Failure to obtain tissue at suction termination of what appears, ultrasonically, to be an intrauterine pregnancy suggests an abnormal site of implantation, including cornual pregnancy [2][4].
These confirm that the TOP is complete and detect complications early.
| Investigation | Timing | Purpose | Key Findings |
|---|---|---|---|
| Inspection of aspirated tissue | Immediately after surgical TOP | Macroscopic confirmation of products of conception (villi appear as frond-like, feathery tissue when floated in saline) | Absence → suspect ectopic/cornual |
| Histopathology | Results in days | Microscopic confirmation; detect molar tissue | As above |
| Serum β-hCG (follow-up) | 1-2 weeks post-procedure (or earlier if concern) | Confirm levels are falling toward zero | Falling → successful TOP. Plateauing/rising → retained products, ectopic, or GTN |
| Pelvic USS | If clinically indicated (ongoing bleeding, pain, suspected retained products) | Assess uterine cavity | Echogenic material > 15 mm → retained products; distended uterus with closed os → haematometra |
| Phase | Investigation | Purpose | Key Interpretation |
|---|---|---|---|
| Bedside | Urine β-hCG | Confirm pregnancy | Negative = not pregnant |
| Imaging | TVUS | Confirm IUP, site, viability, gestation | IUP → proceed; empty uterus → PUL/ectopic workup; snowstorm → molar |
| Bloods (routine) | FBC | Baseline Hb, detect anaemia/infection | Low Hb → optimise; high WBC → infection |
| Blood group + Rh | Rh status | Rh-negative → anti-D needed | |
| Group and save / crossmatch | Prepare for haemorrhage | Hold serum or crossmatch per risk level | |
| Bloods (as indicated) | Serum β-hCG (quantitative) | PUL workup; post-TOP follow-up | Serial trend more useful than single value |
| Coagulation | Bleeding risk assessment | Deranged → correct before procedure | |
| STI screen or prophylactic Abx | Prevent post-TOP infection | Treat positives; or give universal Abx | |
| Tissue | Histology of evacuated products | Confirm complete evacuation; exclude mole | No villi → ectopic workup; hydropic villi → GTD |
| Post-procedure | Serum β-hCG (follow-up) | Confirm resolution | Should fall to < 5 within weeks |
| Pelvic USS (if symptomatic) | Detect retained products / haematometra | Echogenic cavity material → re-evacuate |
This is such a common and high-yield clinical scenario that it deserves its own mini-algorithm:
PUL and TOP — The Clinical Dilemma
If a woman requests TOP but has a pregnancy of unknown location (PUL), you cannot proceed with TOP until you have confirmed it is an IUP. This is frustrating for the patient but is a safety imperative:
- Evacuating the uterus when the pregnancy is ectopic → catastrophic
- Management should not be based solely on a single β-hCG level [5]
- The patient needs serial β-hCG + repeat USS until the location is confirmed
- In the meantime, safety-netting is essential: advise to return immediately if severe pain, heavy bleeding, dizziness, or syncope
Diagnostic laparoscopy is listed as an investigation for ectopic pregnancy [5].
When indicated in the TOP context:
- Suspected ectopic with inconclusive USS and concerning clinical picture
- Haemodynamically unstable patient with positive β-hCG and no IUP on USS
- Laparoscopy, and/or laparotomy, is essential if perforation of the uterus occurs during suction termination of pregnancy, because of the risk of bowel damage and life-threatening sequelae [2][4]
What it provides:
- Direct visualisation of the pelvis — can see ectopic pregnancy, haemoperitoneum, tubal pathology, bowel injury
- Therapeutic: can proceed to salpingectomy, salpingotomy, or repair of perforation in the same setting
High Yield Summary
Pre-TOP Investigations — The Minimum Set:
- Urine β-hCG — confirm pregnancy (negative rules out ectopic)
- TVUS — confirm IUP, site, viability, gestational age (CRL)
- FBC — baseline Hb, detect anaemia
- Blood group + Rh — anti-D if Rh-negative
- Group and save — prepare for possible haemorrhage
- STI screening or prophylactic antibiotics — prevent post-TOP infection
- Legal documentation — two doctors certify grounds; informed consent
Discriminatory Zone: β-hCG 1,000-2,000 mIU/mL — above this, IUP should be visible on TVUS. If not → suspect ectopic. BUT do not make irreversible decisions on a single value in stable patients.
Serial β-hCG (48h): Rising ≥ 66% = likely viable IUP; rising < 66% = abnormal (ectopic/failing); falling = resolving.
Post-TOP Confirmation: Inspect and send products for histology. No villi = suspect ectopic/cornual. Follow-up β-hCG to confirm resolution.
USS Landmarks: GS at 5 weeks → YS at 6 weeks (confirms IUP) → FH at 6-7 weeks (confirms viability).
Active Recall - Diagnostic Criteria, Algorithm, and Investigations for TOP
References
[2] Lecture slides: GCBC-OG-Gyn Emergency_Notes to students_Sep2024.pdf; Block C - Gyanecological Emergency Notes to Students.pdf [4] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf [5] Lecture slides: GC 223. Complications of Early Pregnancy.pdf [6] Senior notes: Maksim Medicine Notes.pdf (hCG homology with TSH section) [7] Senior notes: Ryan Ho GI.pdf (Acute abdomen investigations) [8] Senior notes: Ryan Ho Fundamentals.pdf (Obstetric examination and imaging) [10] Senior notes: Ryan Ho Radiology.pdf (Obstetric imaging — USS landmarks) [11] Senior notes: Ryan Ho Haemtology.pdf (DIC — obstetric causes including septic abortion) [12] Senior notes: Ryan Ho Rheumatology.pdf (Antiphospholipid syndrome — Sapporo criteria)
Management of Termination of Pregnancy
Management of TOP is a structured, stepwise process. The overarching framework is:
- Pre-procedure preparation (counselling, legal, investigations — covered in prior sections)
- Choosing the method (medical vs surgical, based on gestational age, patient factors, and preference)
- Performing the procedure
- Post-procedure care (confirm completion, manage pain, start contraception, follow-up)
- Managing complications (covered in the next section)
The key decision point is which method to use and when. Let me walk through the entire management algorithm, then discuss each treatment modality in depth with indications, contraindications, protocols, and the pharmacological reasoning behind every drug.
Treatment Modality 1: Medical TOP
Medical TOP uses pharmacological agents to induce expulsion of the pregnancy — essentially "inducing a miscarriage" in a controlled setting.
The Standard Regimen: Mifepristone + Misoprostol
This is the gold-standard combination used worldwide (WHO, RCOG, NICE, FIGO all endorse it). Let me explain the pharmacology from first principles, then the protocols.
Mifepristone (RU-486) [3]:
- Drug class: Competitive progesterone receptor antagonist (also has anti-glucocorticoid activity) [3]
- Mechanism of action — think about what progesterone does in pregnancy, then imagine blocking all of it:
| Normal Progesterone Action | Effect of Mifepristone Blocking It |
|---|---|
| Maintains the decidua (thick, nutritive endometrium supporting the embryo) | Decidual necrosis → embryo detaches from uterine wall |
| Suppresses myometrial contractions (keeps the uterus "quiet") | Myometrium becomes contractile → responsive to prostaglandins |
| Maintains cervical closure (keeps the cervix firm and shut) | Cervix softens and begins to dilate |
| Down-regulates prostaglandin receptors (reducing sensitivity) | Up-regulates prostaglandin receptors → myometrium becomes hyper-sensitive to misoprostol |
- Dose: 200 mg orally, single dose [3]
- Timing: Given 24–48 hours before the prostaglandin (misoprostol or gemeprost)
- Half-life: ~25–30 hours → long enough that a single dose persists to prime the uterus
- Side effects: Nausea, vomiting, light vaginal bleeding (from decidual breakdown beginning), abdominal cramps [3]
- Important: Mifepristone alone achieves complete abortion in only ~60–80% of very early pregnancies ( < 7 weeks). The addition of misoprostol raises this to > 95–98%.
Misoprostol [3]:
- Drug class: Synthetic prostaglandin E1 (PGE1) analogue [3]
- Mechanism: Binds to EP2/EP3 receptors on myometrial smooth muscle → increases intracellular Ca²⁺ → powerful uterine contractions. Also activates collagenase in the cervix → cervical ripening and dilation [3]
- Why PGE1? Natural prostaglandins have very short half-lives (minutes) because they are rapidly metabolised. Misoprostol is a synthetic analogue with a methyl ester group that protects it from degradation → oral bioavailability and longer duration.
Routes and their properties [3]:
| Route | Onset | Peak Effect | Bioavailability | Key Advantages/Disadvantages |
|---|---|---|---|---|
| Vaginal | 20-30 min | 60-120 min | Highest | Most effective uterine action; fewer GI side effects; slower onset |
| Sublingual | 10-15 min | 30 min | High | Fastest onset; more GI side effects (diarrhoea, shivering) |
| Buccal | 15-20 min | 60 min | Intermediate | Good balance of speed and tolerability |
| Oral | 8-10 min | 30 min | Lowest | Most convenient; but shortest duration and most GI side effects |
Side effects [3]:
- Diarrhoea — PGE1 stimulates GI smooth muscle (same mechanism that makes it contract the uterus)
- Nausea and vomiting — prostaglandin-mediated
- Fever and chills — PGE1 acts on the hypothalamic thermostat (prostaglandins are the mediators of fever in inflammation too — same principle here, just iatrogenic)
- Shivering — especially with sublingual route
- All these are transient ( < 24 hours) and are expected pharmacological effects, not complications
Early first trimester (≤ 9 weeks / 63 days) — the most common scenario:
| Step | Drug | Dose | Route | Timing |
|---|---|---|---|---|
| 1 | Mifepristone | 200 mg | Oral | Day 1 (in clinic) |
| 2 | Misoprostol | 800 μg | Vaginal, sublingual, or buccal | 24-48 hours after mifepristone |
- The woman takes mifepristone in the clinic, then returns 24–48 hours later for misoprostol
- Increasingly, home use of misoprostol is offered (the woman takes it at home after returning from the clinic with mifepristone) — this is endorsed by WHO and NICE (2024) for gestations ≤ 10 weeks
- Expected timeline: Bleeding and cramping typically begin 1–4 hours after misoprostol; the gestational sac is usually expelled within 4–6 hours; total process may take 1–2 days
- Success rate: > 95–98% complete abortion [3]
9–12 weeks:
- Same drugs but efficacy of medical TOP decreases slightly (larger products, more tissue to pass)
- May require additional doses of misoprostol (400 μg vaginally or sublingually, repeated every 3 hours, up to 4 additional doses)
- Many clinicians prefer surgical TOP at this gestation for speed and reliability
Second trimester (13–24 weeks) [3]:
| Step | Drug | Dose | Route | Timing |
|---|---|---|---|---|
| 1 | Mifepristone | 200 mg | Oral | 36-48 hours before misoprostol |
| 2 | Misoprostol | 400 μg | Vaginal (first dose), then vaginal or sublingual | Every 3 hours (max 5 doses in 24h) |
| 3 | If no expulsion after max misoprostol | Reassess — may add oxytocin infusion or repeat cycle next day |
- This is essentially an induction of labour — the woman goes through labour-like contractions and delivers the fetus vaginally
- More painful than first-trimester medical TOP → adequate analgesia essential (opioids, epidural if available)
- Takes longer: average 6–12 hours from first misoprostol dose; may take up to 24–48 hours [3]
- After fetal expulsion, the placenta may be retained → may require manual removal of placenta or surgical evacuation of retained placental tissue
Alternative prostaglandin: Gemeprost [3]:
- Synthetic PGE1 analogue, administered as a vaginal pessary (1 mg) [3]
- Must be stored at -10°C to -20°C (requires a functioning cold chain — a significant logistical disadvantage)
- Used mainly for second-trimester TOP [3]
- Dose: 1 mg vaginally every 3 hours (maximum 5 pessaries in 24 hours)
- More expensive than misoprostol
- In practice, misoprostol has largely replaced gemeprost in many settings due to cost, stability, and ease of administration
Oxytocin as adjunct [3]:
- Oxytocin acts on oxytocin receptors (Gq-coupled) on myometrial cells → ↑ intracellular Ca²⁺ → contraction [3]
- Sensitivity of the myometrium to oxytocin increases throughout pregnancy [3] → this is why oxytocin is ineffective in early pregnancy (too few receptors) but useful in the second trimester and especially at term
- Used as adjunct in second-trimester medical TOP when misoprostol alone is insufficient
- Typical regimen: Syntocinon 20–40 units in 500 mL normal saline, titrated
- Side effect at high doses: ADH-like water retention → hyponatraemia → seizures [3] — manage by limiting IV fluid volume and monitoring electrolytes
| Indication | Rationale |
|---|---|
| Patient preference for non-surgical approach | Many women prefer to avoid anaesthesia and instrumentation |
| Early pregnancy (≤ 9 weeks) — first-line option | Highest success rate with lowest complication rate at this gestation |
| Second-trimester TOP (13–24 weeks) — often preferred | There remain questions as to whether dilatation and evacuation is a safe and appropriate method of terminating second trimester pregnancies when effective medical alternatives exist [2] |
| No access to surgical facilities | Medical TOP can be administered in outpatient/primary care settings |
| Cervical stenosis (relative indication) | Avoids the need for mechanical cervical dilation |
| Contraindication | Reason |
|---|---|
| Confirmed or suspected ectopic pregnancy | Medical TOP will NOT treat an ectopic — the uterine pregnancy will bleed but the ectopic persists and can rupture |
| Chronic adrenal failure or current systemic corticosteroid therapy | Mifepristone has anti-glucocorticoid activity → can precipitate adrenal crisis |
| Known allergy to mifepristone or misoprostol | Anaphylaxis risk |
| Inherited porphyria | Mifepristone may exacerbate porphyria |
| Haemorrhagic disorder or concurrent anticoagulant therapy | Medical TOP causes significant bleeding; uncontrolled coagulopathy → haemorrhagic risk |
| IUD in situ | Must remove IUD before medical TOP (if IUD with pregnancy, removal is needed regardless) |
| Severe uncontrolled asthma (relative) | Prostaglandins (especially PGF2α) can cause bronchospasm. PGE1 (misoprostol) is less bronchoconstrictive, but caution is needed in severe asthma |
Mifepristone and Adrenal Insufficiency — Why?
Mifepristone is structurally similar to cortisol (both are steroids). It blocks the progesterone receptor but also blocks the glucocorticoid receptor. In a healthy person, the adrenal glands compensate by producing more cortisol. But in someone with adrenal insufficiency (e.g., Addison's disease, or on chronic steroids with suppressed HPA axis), they cannot mount this compensatory response → acute adrenal crisis. This is why chronic adrenal failure is an absolute contraindication.
Treatment Modality 2: Surgical TOP
Surgical TOP physically removes the pregnancy from the uterus. The specific technique depends on gestational age.
- Gestation: Up to ~12 weeks (optimally ≤ 10 weeks)
- What it is: A handheld 60 mL syringe creates a vacuum; attached to a cannula inserted through the cervix into the uterus
- Anaesthesia: Can be performed under local anaesthesia (paracervical block) ± conscious sedation
- Advantages: No electricity needed; portable; quiet; can be done in outpatient/clinic setting; lower cost
- Procedure:
- Cervical priming (misoprostol 400 μg vaginally 3h before, or mifepristone 200 mg orally 24-48h before)
- Paracervical block with lignocaine
- Gentle cervical dilation with Hegar dilators if needed
- Insert appropriately sized cannula
- Create vacuum with syringe
- Aspirate uterine contents with gentle rotational movements
- Inspect tissue — look for gestational sac, villi
- Send for histology
- Gestation: The most commonly used surgical method for first-trimester TOP (up to ~12-14 weeks) [2]
- What it is: An electric pump creates continuous suction through a cannula inserted into the uterus
- Anaesthesia: Usually general anaesthesia (in HK) or conscious sedation
- Procedure:
- Cervical priming — recommended for all women, especially:
- Nulliparous women
- Women < 18 years
- Gestations > 10 weeks
- Methods: misoprostol 400 μg vaginally 3h before; or osmotic dilators (laminaria/Dilapan-S) inserted 4-24h before
- Cervical dilation — using graduated Hegar dilators, to the appropriate size for the cannula (generally cannula size in mm ≈ gestational age in weeks)
- Suction aspiration — cannula attached to electric vacuum pump; systematic aspiration of all four quadrants
- Optional gentle sharp curettage — some operators perform a light "check curettage" to ensure completeness (though routine curettage is increasingly discouraged as it damages the basalis layer and increases Asherman syndrome risk)
- Inspect aspirate — float tissue in saline, identify chorionic villi macroscopically
- Send for histopathology
- Cervical priming — recommended for all women, especially:
Key safety point: Failure to obtain tissue at suction termination of what appears, ultrasonically, to be an intrauterine pregnancy suggests an abnormal site of implantation, including cornual pregnancy [2][4].
- Gestation: Second trimester (typically > 14 weeks) [2]
- There remain questions as to whether dilatation and evacuation is a safe and appropriate method of terminating second trimester pregnancies when effective medical alternatives exist [2] — this is the lecture's explicit caution about D&E
- What it is: More extensive cervical dilation + combination of suction and forceps extraction
- Anaesthesia: General anaesthesia
- Procedure:
- Cervical preparation (essential — more dilation needed than first trimester):
- Osmotic dilators (laminaria or Dilapan-S) inserted the day before (or same day for 14-16 weeks)
- ± Mifepristone 200 mg orally 24-48h before
- ± Misoprostol on the day
- Cervical dilation — up to 14-20 mm depending on gestation
- Evacuation — using Sopher forceps, Bierer forceps, and/or suction; fetal parts and placenta removed under ultrasound guidance
- Check curettage — gentle suction to ensure cavity is empty
- Tissue inspection — must account for all fetal parts and placenta
- Cervical preparation (essential — more dilation needed than first trimester):
- Requires an experienced operator [2] — the risk of complications (perforation, haemorrhage, cervical laceration, retained products) is significantly higher than first-trimester procedures
- Advantage over medical TOP: Faster (single procedure, usually < 30 minutes) and more predictable timing; avoids labour-like experience
- Disadvantage: Higher surgical risk; requires general anaesthesia and experienced surgeon
D&E — The Exam Stance
The lecture explicitly questions whether D&E is safe and appropriate for second-trimester TOP when medical alternatives exist [2]. In an exam, if asked about second-trimester TOP, the safest answer is:
- Medical TOP (mifepristone + misoprostol/gemeprost) is the preferred method for most second-trimester cases
- D&E is an alternative when performed by an experienced operator, and may be appropriate when medical TOP has failed or is contraindicated
- Always mention that the choice depends on gestational age, operator experience, patient preference, and clinical circumstances
- Essentially a mini-caesarean section [2]
- Rarely used — reserved for:
- Failed medical and surgical TOP
- Contraindications to other methods
- Very late gestations with specific indications (e.g., placenta praevia precluding vaginal delivery)
- Higher morbidity — it is a major abdominal operation with all the risks of laparotomy
- Creates a uterine scar → implications for future pregnancies (risk of uterine rupture in subsequent labour)
- Almost never the first-line choice in modern practice
| Indication | Rationale |
|---|---|
| Patient preference | Some women prefer the "one and done" approach — a single procedure under anaesthesia |
| Gestational age 9–14 weeks | Surgical aspiration is faster and more reliable than medical at this gestation |
| Failed medical TOP | If medical TOP does not achieve complete expulsion, surgical evacuation is the rescue |
| Contraindications to medical TOP | Adrenal failure, severe asthma, allergy to mifepristone/misoprostol |
| Molar pregnancy | Suction evacuation is the preferred method for molar pregnancy (not medical TOP) — allows tissue collection for histology and avoids prolonged uterine stimulation |
| Need for concurrent IUD/IUS insertion | IUD can be inserted immediately after surgical evacuation |
| Contraindication | Reason |
|---|---|
| Unfit for anaesthesia | If the woman cannot safely undergo general anaesthesia or sedation (though MVA under local is an option) |
| Cervical stenosis that cannot be overcome | Risk of false passage, perforation; may need medical priming first |
| Active pelvic infection (untreated) | Instrumentation spreads infection → sepsis; in cases of septic abortion, evacuation should be performed by experienced surgeons, optimally around one hour after intravenous antibiotics [2] |
| Coagulopathy (uncontrolled) | Surgical intervention with uncontrolled bleeding → haemorrhage |
| Ectopic pregnancy | Uterine instrumentation will not treat an ectopic pregnancy |
Cervical Priming — A Detailed Overview
Cervical priming deserves its own section because it is the single most important step in reducing surgical complications. Think of the cervix as a gatehouse — trying to force it open damages the gate.
The non-pregnant cervix (and early pregnant cervix, especially in nulliparas) is firm, predominantly composed of collagen and smooth muscle. Rapid mechanical dilation without softening risks:
- Cervical laceration — tears in the cervical tissue, which can bleed and heal with fibrosis
- Uterine perforation — the instrument passes through the weakened or thin area
- Cervical incompetence — damage to the internal os → future pregnancies at risk of second-trimester miscarriage or preterm birth
| Method | Mechanism | Protocol | Best For |
|---|---|---|---|
| Misoprostol [3] | PGE1 → activates collagenase in cervical stroma → breaks down collagen → softening + dilation | 400 μg vaginally 3h before procedure (or sublingual 2-3h before) | First-trimester surgical TOP; convenient, rapid |
| Mifepristone [3] | Anti-progesterone → cervical softening via loss of progesterone-mediated collagen cross-linking | 200 mg orally 24-48h before procedure | Can be combined with misoprostol for greater effect; used for second-trimester preparation |
| Osmotic dilators (Laminaria japonica) | Natural seaweed sticks inserted into cervical canal → absorb moisture from cervical mucus → swell slowly over 12-24h → gradual, gentle mechanical dilation | Insert 12-24h before procedure; number depends on gestation (more for later gestations) | Second-trimester D&E; provides significant dilation without forceful manipulation |
| Synthetic osmotic dilators (Dilapan-S) | Same principle as laminaria but synthetic hydrogel; more predictable swelling | Insert 4-24h before procedure | Alternative to laminaria; more consistent |
WHO recommends cervical priming for all surgical TOPs. At minimum:
- All gestations > 12 weeks (essential)
- Nulliparous women at any gestation
- Women < 18 years
- Any woman with known cervical stenosis or previous cervical surgery
Perioperative Care
- Recommended for ALL surgical TOPs to reduce the risk of post-procedure infection (endometritis, PID)
- Regimens vary:
- Doxycycline 100 mg PO 1h before + 200 mg PO after procedure, OR
- Azithromycin 1g PO on the day of procedure, OR
- Metronidazole 1g PR at time of procedure (if nil by mouth)
- In cases of septic abortion, evacuation of the uterus should be performed by experienced surgeons, optimally around one hour after intravenous antibiotics [2] — this is a specific scenario requiring therapeutic (not prophylactic) antibiotics:
- Broad-spectrum IV antibiotics covering Gram-negative, Gram-positive, and anaerobes (e.g., IV cefuroxime + metronidazole + gentamicin, or piperacillin-tazobactam)
- Evacuation performed ~1 hour after starting IV antibiotics (allows tissue antibiotic levels to rise)
- All Rh-negative women must receive anti-D within 72 hours of the procedure [2]
- ≤ 12 weeks: 250 IU IM
- > 12 weeks: 500 IU IM + Kleihauer-Betke test
| Procedure Type | Analgesia |
|---|---|
| Medical TOP (first trimester, home) | NSAIDs (ibuprofen 400-600 mg PO q6-8h) ± paracetamol; codeine if needed |
| Medical TOP (second trimester, inpatient) | Opioids (morphine PCA or IM pethidine); ± epidural analgesia; NSAIDs as adjunct |
| Surgical TOP (first trimester) | General anaesthesia (most common in HK) or conscious sedation + paracervical block |
| Surgical TOP (second trimester D&E) | General anaesthesia |
Fertility returns rapidly after TOP (ovulation can occur within 2 weeks) [3]. Starting contraception immediately is critical to prevent repeat unintended pregnancy.
| Method | When to Start | Notes |
|---|---|---|
| COCP / POP | Day of or day after the procedure [3] | |
| Depo-Provera | Day of procedure [3] | |
| Implant (Nexplanon) | Day of procedure [3] | Can be inserted in the arm at the time of surgical TOP |
| IUD / IUS | Immediately after surgical evacuation [3] | Highly effective; inserted while the cervix is still dilated; proven safe and does not increase infection risk |
| Condoms | Immediately | Lower efficacy but immediately available |
LARC at Time of TOP — Best Practice
Inserting a long-acting reversible contraceptive (IUD/IUS or implant) at the time of surgical TOP is the single most effective way to reduce repeat unintended pregnancy. Studies show:
- Immediate IUD insertion post-surgical TOP has an expulsion rate of ~3-5% (slightly higher than interval insertion) but vastly better outcomes than deferring to a follow-up visit (where many women do not return)
- Immediate implant insertion has no increased complication rate
- This should be offered and discussed at counselling
Management of Specific Scenarios
- Definition: Ongoing viable pregnancy after completing the medical TOP regimen (occurs in ~2-5% of cases)
- Detection: Persistent pregnancy symptoms; USS shows viable IUP with cardiac activity; β-hCG rising or plateau
- Management: Surgical evacuation (suction aspiration) — this is the definitive rescue
- Important: If the woman has taken mifepristone but then changes her mind ("reversal"), there is no proven effective "reversal" protocol. Mifepristone alone has a 40% failure rate (pregnancy may continue), but the evidence for high-dose progesterone "reversal" is very weak.
- Definition: Products of conception partially expelled/removed; retained tissue in the uterine cavity
- Presentation: Ongoing heavy bleeding, persistent cramping, open cervical os, echogenic material > 15 mm in uterine cavity on USS
- Management:
- If asymptomatic or minimally symptomatic with small retained products: expectant management (may pass spontaneously) or repeat misoprostol (800 μg vaginal, single dose)
- If heavy bleeding or symptomatic: surgical evacuation (suction aspiration)
When there is evidence of rapid clinical deterioration postoperatively, or in association with miscarriage, and especially when sepsis is suspected, it is vital that there is direct and rapid involvement of senior obstetric staff and other relevant specialists including intensive care doctors [2].
- Presentation: Fever > 38°C, foul-smelling vaginal discharge, uterine tenderness, tachycardia, hypotension
- Management:
- A-B-C resuscitation — IV access, bloods (FBC, CRP, blood cultures, lactate, coagulation), IV fluids
- IV broad-spectrum antibiotics — start IMMEDIATELY (e.g., IV amoxicillin + gentamicin + metronidazole; or piperacillin-tazobactam)
- Evacuation of the uterus by experienced surgeons, optimally around one hour after intravenous antibiotics [2]
- ICU referral if haemodynamically unstable or signs of septic shock
- Monitor for DIC (septic abortion is a recognised cause of obstetric DIC [11])
Laparoscopy, and/or laparotomy, is essential if perforation of the uterus occurs during suction termination of pregnancy, because of the risk of bowel damage and life-threatening sequelae [2][4].
- When suspected: Sudden loss of resistance during instrumentation; instrument passes further than expected; sudden pain; bleeding
- Management:
- STOP the procedure immediately
- Assess haemodynamic stability
- Diagnostic laparoscopy — to:
- Confirm perforation site and size
- Assess for bowel injury (bowel may have been sucked into the uterus through the perforation)
- Assess for intra-abdominal haemorrhage
- If bowel injury found → laparotomy for repair
- If small uterine perforation only, no bowel injury → conservative management with observation, IV antibiotics, serial vitals
- If large perforation or uncontrolled bleeding → surgical repair (laparotomy, uterine repair)
- Presentation: Severe cramping within hours to days of procedure; tender, enlarged, boggy uterus; closed cervical os; minimal external bleeding
- Mechanism: Cervix clamps down → blood trapped in uterus → distension → pain + prevents myometrial contraction → more bleeding into trapped space
- Management:
- Re-evacuation of the uterus (suction aspiration)
- Uterotonics (oxytocin) post-evacuation
- Rapid relief of symptoms after evacuation
| Feature | Medical TOP | Surgical TOP |
|---|---|---|
| Gestational range | ≤ 9 weeks (first line); 13-24 weeks | 7-14 weeks (first line); D&E for second trimester |
| Anaesthesia | None (outpatient) | Local (MVA) or general (EVA, D&E) |
| Completion rate | 95-98% (first trimester) | > 99% |
| Need for surgical intervention | 2-5% require surgical completion | Already surgical |
| Time to completion | Hours to days | Minutes (procedure itself) |
| Pain | Significant cramping (labour-like in 2nd trimester) | Minimal post-procedure (under anaesthesia) |
| Privacy / control | Can be done at home (≤ 10 weeks) | Requires clinic/hospital |
| Serious complications | Rare (haemorrhage, infection) | Rare (perforation, cervical laceration, infection) |
| Contraception timing | Start same day | IUD can be inserted immediately |
| Follow-up | Essential (confirm completion) | Less critical (if products confirmed at time) |
High Yield Summary
Method Selection:
- ≤ 9 weeks: Medical (mifepristone 200 mg PO + misoprostol 800 μg vaginal 24-48h later) OR surgical (MVA/suction aspiration) — patient choice
- 9-14 weeks: Surgical (suction aspiration) preferred; medical also possible
- 14-24 weeks: Medical (mifepristone + repeated misoprostol/gemeprost) preferred; D&E only by experienced operator
- Molar pregnancy: Suction evacuation (NOT medical TOP)
Key Drugs:
- Mifepristone: anti-progesterone → decidual necrosis, cervical softening, prostaglandin receptor upregulation
- Misoprostol: PGE1 → uterine contractions + cervical ripening; vaginal route most effective
- Gemeprost: PGE1 pessary; needs cold storage; second-trimester use
- Oxytocin: adjunct in second trimester; ineffective alone in early pregnancy
Cervical Priming: Recommended for ALL surgical TOP; essential > 12 weeks, nulliparous, < 18 years
Perioperative Must-Dos: Prophylactic antibiotics + Anti-D (if Rh-negative) + Analgesia + Immediate contraception
Complication Management:
- No products at evacuation → suspect ectopic/cornual → urgent evaluation
- Perforation → stop procedure → laparoscopy/laparotomy (bowel injury risk)
- Septic abortion → IV antibiotics → experienced surgical evacuation ~1h after
- Haematometra → re-evacuation + uterotonics
Active Recall - Management of Termination of Pregnancy
References
[2] Lecture slides: GCBC-OG-Gyn Emergency_Notes to students_Sep2024.pdf; Block C - Gyanecological Emergency Notes to Students.pdf [3] Lecture slides: Block C - The woman needs that drug_ Oral contraceptives, Drugs affecting uterine motility.pdf [4] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf [10] Senior notes: Ryan Ho Radiology.pdf (Obstetric imaging) [11] Senior notes: Ryan Ho Haemtology.pdf (DIC — obstetric causes) [13] Senior notes: Ryan Ho Diagnostic Radiology.pdf (Uterine artery embolisation for PPH)
Complications of Termination of Pregnancy
Complications of TOP can be organised by timing (immediate, early, late) and by method (medical vs surgical). Understanding the pathophysiology of each complication is the key to recognising, preventing, and managing them. Overall, TOP is a safe procedure when performed correctly — the complication rate for first-trimester TOP is very low (< 1% for serious complications). However, complications rise substantially with increasing gestational age, and some are life-threatening if missed.
The mnemonic "CHIPS" can help you remember the major complications:
- C — Cervical laceration
- H — Haemorrhage
- I — Infection (endometritis / septic abortion)
- P — Perforation (uterine)
- S — Sequelae (long-term: Asherman syndrome, cervical incompetence, psychological, Rh sensitisation)
| Timing | Complications |
|---|---|
| Immediate (during or within hours) | Haemorrhage, uterine perforation, cervical laceration, anaesthetic complications, vasovagal reaction, failed TOP |
| Early (days to weeks) | Incomplete abortion / retained products, endometritis / septic abortion, haematometra, continuing pregnancy (failed TOP) |
| Late (weeks to months / years) | Asherman syndrome (intrauterine adhesions), cervical incompetence, Rh isoimmunisation (if anti-D missed), psychological sequelae, impact on future fertility |
1. Haemorrhage
Incidence: ~1 in 1,000 for first-trimester TOP requiring transfusion; higher in second-trimester procedures
After the pregnancy is removed, the placental bed is a raw, vascular surface where remodelled spiral arteries previously supplied the placenta with high-volume, low-resistance blood flow. Haemostasis depends on three mechanisms:
- Myometrial contraction — the interlacing smooth muscle fibres of the middle myometrial layer act as a "living ligature," compressing the blood vessels running through them (the same principle as in postpartum haemorrhage)
- Local coagulation — clot formation at the vessel ends
- Endometrial regeneration — eventually the endometrium regrows over the raw surface
If any of these mechanisms fail, bleeding continues.
| Cause | Mechanism | Risk Factors |
|---|---|---|
| Retained products of conception | Retained trophoblastic/decidual tissue physically prevents the myometrium from contracting fully around the blood vessels (the tissue acts as a "wedge" holding the uterus open) | Incomplete evacuation, medical TOP (2-5% incomplete), advanced gestation |
| Uterine atony | The myometrium fails to contract adequately — blood vessels remain unsupported and bleed freely | Grand multiparity (uterus "exhausted"), prolonged procedure, uterine fibroids, second-trimester TOP |
| Cervical laceration | Torn cervical tissue with exposed vessels bleeds directly | Forceful dilation without adequate priming, nulliparous cervix, advanced gestation |
| Uterine perforation | Instrument perforates through the myometrium into the peritoneal cavity → intra-abdominal bleeding (may be concealed) | Retroverted uterus, previous caesarean scar, inexperienced operator, advanced gestation |
| Coagulopathy | Failure of the clotting cascade → continued oozing | Pre-existing bleeding disorder, anticoagulant use, DIC (especially in septic abortion [11]) |
- Resuscitate: A-B-C approach; IV access ×2 large-bore; bloods (FBC, crossmatch, coagulation); IV crystalloid ± blood products
- Identify the cause:
- Speculum examination — cervical laceration visible? Products at the os?
- Bimanual examination — bulky, boggy uterus (atony / retained products)? Firm, distended uterus with closed os (haematometra)?
- Pelvic USS — retained echogenic material in the cavity?
- Treat the cause:
-
Retained products → surgical evacuation (suction aspiration)
-
Uterine atony → uterotonics (same drugs as for PPH):
Drug Mechanism Route Notes Oxytocin Oxytocin receptor agonist → myometrial contraction [3] IV infusion (20-40 IU in 500 mL NS) or IM 5 IU First line Ergometrine Acts on α-adrenergic and serotonin receptors on smooth muscle → sustained tonic contraction IM 0.5 mg or IV 0.25 mg (slow) Contraindicated in hypertension, pre-eclampsia (causes vasoconstriction → hypertensive crisis) Misoprostol [3] PGE1 → myometrial contraction 800 μg sublingual or 1000 μg rectal Useful when IV access unavailable Carboprost (15-methyl-PGF2α) [3] PGF2α analogue → powerful myometrial contraction IM 250 μg, repeat q15min (max 8 doses) Contraindicated in asthma (PGF2α causes bronchospasm) -
Cervical laceration → direct suture repair under vision
-
Perforation → see below
-
Coagulopathy → correct with FFP, cryoprecipitate, platelets as indicated; if DIC → treat underlying cause (usually sepsis)
-
Uterine artery embolisation (UAE) [13] — interventional radiology option for refractory uterine bleeding unresponsive to uterotonics and surgical measures; preferred over surgery for pelvic haemorrhage due to complex anatomy [13]
-
2. Uterine Perforation
Incidence: 1–4 per 1,000 surgical TOPs (higher in second-trimester D&E)
Exam question stem: "A 24-year-old woman, G1P0, was referred from the Family Planning Association one day after suction evacuation for an unplanned and unwanted pregnancy. Intraoperatively, there was a 'give-way' sensation by the surgeon. The patient complained of mild vaginal bleeding but was otherwise well. Her BP was 120/80 mmHg, and her pulse was 80 bpm. The MOST LIKELY diagnosis is uterine perforation." [14]
The uterus is a muscular organ, but during pregnancy its wall is softer, more vascular, and in certain areas (e.g., the isthmus or a previous caesarean scar) may be thin. Perforation occurs when an instrument — dilator, curette, suction cannula, or forceps — passes through the full thickness of the myometrium into the peritoneal cavity.
The "give-way" sensation: When a dilator or curette meets resistance from the cervix/myometrium and then suddenly loses resistance, it indicates the instrument has penetrated through the wall. An experienced operator will feel the instrument go "further than it should."
| Risk Factor | Why |
|---|---|
| Retroverted uterus | The fundus points posteriorly → instruments following the "expected" anteverted path may perforate the posterior wall |
| Previous caesarean section | Scar tissue at the lower segment is thinner and more vulnerable — the instrument can perforate at the scar |
| Advanced gestation | Uterine wall is thinner; more forceful dilation needed |
| Inexperienced operator | Excessive force, incorrect angle of instrumentation |
| Cervical stenosis | Difficulty dilating → may create a false passage |
| Uterine anomalies | Bicornuate, septate uterus → altered anatomy |
- Fundus (most common) — the cannula passes through the thinnest part at the top of the uterus
- Isthmus / lower segment — especially at previous caesarean scar
- Lateral wall — risk of uterine vessel injury → significant haemorrhage
The perforation itself may be small and self-limiting. The danger is what happens next:
- Bowel injury: If suction is applied after perforation, bowel loops can be drawn into the uterus through the perforation → bowel laceration, devascularisation, or transection → peritonitis → sepsis → death if unrecognised
- Haemoperitoneum: Perforation through a vascular area → intra-abdominal bleeding → concealed haemorrhage (patient may become hypotensive without visible vaginal bleeding)
- Bladder injury: Anterior perforation may involve the bladder (rare — the bladder sits anterior to the lower uterine segment)
Laparoscopy, and/or laparotomy, is essential if perforation of the uterus occurs during suction termination of pregnancy, because of the risk of bowel damage and life-threatening sequelae [2][4].
| Step | Action | Rationale |
|---|---|---|
| 1 | STOP the procedure immediately | Prevent further damage |
| 2 | Assess haemodynamics | Tachycardia / hypotension → concealed haemorrhage |
| 3 | Keep nil by mouth | Prepare for possible surgery |
| 4 | Diagnostic laparoscopy [2][4] | Visualise perforation site; assess bowel and bladder integrity; identify haemoperitoneum |
| 5a | If small fundal perforation, no bowel injury, haemodynamically stable | Conservative: IV antibiotics, observation (serial vitals, Hb), analgesia; complete the evacuation under USS guidance from above |
| 5b | If bowel injury identified | Laparotomy for bowel repair (may need resection and anastomosis or stoma depending on extent) |
| 5c | If significant haemorrhage | Laparotomy: repair perforation, achieve haemostasis; rarely hysterectomy if uncontrollable |
Never Ignore the 'Give-Way'
The classic exam scenario is the "give-way" during suction TOP. Even if the patient appears well post-procedure (as in the exam question above [14]), uterine perforation must be assumed. Delayed presentation with peritonitis from unrecognised bowel injury is catastrophic. Laparoscopy is the standard of care to exclude bowel damage.
3. Infection (Endometritis / Septic Abortion)
Incidence: ~3% without antibiotic prophylaxis; < 1% with prophylactic antibiotics
The lower genital tract (vagina, ectocervix) harbours a normal flora of bacteria. During TOP — whether medical (cervix opens, products pass through) or surgical (instruments pass through the cervix) — bacteria can ascend into the normally sterile uterine cavity. This is called ascending infection.
The risk is amplified by:
- Retained products of conception — necrotic tissue serves as an excellent culture medium for bacteria (provides nutrients and a warm, moist environment)
- Instrumentation — disrupts the cervical mucus barrier, introduces organisms mechanically
- Pre-existing STI (especially Chlamydia trachomatis, Neisseria gonorrhoeae) — organisms already present in the cervix are pushed upward
- Prolonged procedure — more time for bacterial contamination
The infection starts as endometritis (infection of the endometrium) → may spread to myometritis → parametritis (infection of the parametrium/broad ligament) → peritonitis → septicaemia/septic shock → multi-organ failure.
| Category | Organisms |
|---|---|
| STIs | Chlamydia trachomatis, Neisseria gonorrhoeae |
| Normal vaginal flora (ascending) | Bacteroides spp, Peptostreptococcus, E. coli, Group B Streptococcus |
| Exogenous (from non-sterile instruments — in unsafe abortion) | Clostridium perfringens (gas gangrene), Staphylococcus aureus |
| Feature | Mechanism |
|---|---|
| Fever ≥ 38°C | Bacterial pyrogens stimulate the hypothalamic thermostat via PGE2 (the same prostaglandin pathway — only this time it's endogenous from infection, not exogenous from misoprostol) |
| Foul-smelling vaginal discharge | Anaerobic bacterial metabolism produces volatile amines and sulphur compounds |
| Uterine tenderness | Inflammation of the endometrium/myometrium → nociceptor stimulation |
| Cervical excitation / motion tenderness | Parametrial inflammation stretches the peritoneum when the cervix is moved |
| Tachycardia, hypotension | Systemic inflammatory response → vasodilation, capillary leak → distributive shock |
| Rigors | Bacteraemia → pyrogen release → shivering thermogenesis |
In cases of septic abortion, evacuation of the uterus should be performed by experienced surgeons, optimally around one hour after intravenous antibiotics [2][4].
When there is evidence of rapid clinical deterioration, and especially when sepsis is suspected, it is vital that there is direct and rapid involvement of senior obstetric staff and other relevant specialists including intensive care doctors [2][4].
| Step | Action |
|---|---|
| 1 | Resuscitate: IV access, bloods (FBC, CRP, blood cultures ×2, lactate, coagulation screen, group and crossmatch), IV crystalloid |
| 2 | IV broad-spectrum antibiotics STAT — cover Gram +ve, Gram −ve, and anaerobes (e.g., IV co-amoxiclav + gentamicin + metronidazole; or piperacillin-tazobactam) |
| 3 | Surgical evacuation ~1 hour after starting IV antibiotics — to remove the nidus of infection (retained products); must be done by experienced surgeon to avoid perforation of the infected, friable uterus |
| 4 | Monitor for DIC — septic abortion is a recognised obstetric cause of DIC [11]; check coagulation, fibrinogen, D-dimer serially |
| 5 | ICU involvement if haemodynamically unstable or features of septic shock |
| 6 | Follow-up: serial clinical assessment, repeat blood cultures, step-down antibiotics when improving |
Prevention of Post-TOP Infection
Prophylactic antibiotics are recommended for ALL surgical TOPs. Evidence-based regimens include:
- Doxycycline 100 mg PO before + 200 mg PO after procedure
- Azithromycin 1 g PO on day of procedure
- Metronidazole 1 g PR at time of procedure
This reduces post-TOP infection rates from ~3% to < 1%. Additionally, STI screening (or universal "screen and treat") further reduces risk.
4. Cervical Laceration
Incidence: < 1% for first-trimester TOP; higher for second-trimester D&E
The cervix is primarily composed of dense fibrous connective tissue (collagen type I and III) with some smooth muscle. Rapid, forceful mechanical dilation — especially without adequate cervical priming — can tear this tissue. The tear usually occurs at the 3 o'clock or 9 o'clock position (where the cervical branches of the uterine artery run).
- Nulliparity (firmer cervix, never dilated before)
- Inadequate cervical priming
- Forceful or rapid dilation
- Advanced gestational age (more dilation needed)
- Operator inexperience
| Immediate | Long-term |
|---|---|
| Bleeding (may be brisk if cervical branch of uterine artery involved) | Cervical incompetence — weakened internal os → unable to remain closed under the weight of a growing fetus → recurrent second-trimester miscarriage or preterm birth in future pregnancies |
- Immediate: Direct suture repair of the laceration under speculum visualisation; sponge forceps to tamponade bleeding; ring forceps applied to the bleeding point
- Prevention: Adequate cervical priming before ALL surgical TOPs (this is why cervical priming is so emphasised — it is the single most effective prevention strategy)
5. Incomplete Abortion / Retained Products of Conception
Incidence: 2–5% for medical TOP; < 1% for surgical TOP
In medical TOP, the pregnancy is expelled by uterine contractions. If contractions are insufficient, or if the products are bulky or adherent, not all tissue passes. In surgical TOP, the operator may fail to evacuate the entire uterine cavity — especially if the uterus has an anomalous shape (septate, bicornuate) or contains fibroids.
Retained tissue has two consequences:
- Prevents full myometrial contraction → ongoing bleeding
- Serves as a nidus for infection → endometritis → septic abortion
| Feature | Mechanism |
|---|---|
| Ongoing heavy vaginal bleeding | Retained tissue prevents "living ligature" compression of spiral arteries |
| Persistent cramping | Uterus continues to contract, trying to expel the retained tissue |
| Open cervical os | Os remains dilated because products are in the lower uterine segment/cervical canal |
| Fever (if infection supervenes) | Ascending infection of retained necrotic tissue |
| Elevated or plateauing β-hCG | Retained trophoblastic tissue continues to secrete hCG |
- Pelvic USS: Echogenic material > 15 mm anteroposterior (AP) diameter in the uterine cavity is suggestive of retained products (though post-procedure appearances can be confusing — blood clot vs tissue)
- Serum β-hCG: Failure to decline suggests retained trophoblast
- Asymptomatic, small remnant: Expectant management (may pass spontaneously) or repeat dose of misoprostol 800 μg vaginally
- Symptomatic (heavy bleeding / infection): Surgical evacuation (suction aspiration)
- Products visible at the cervical os: Remove with sponge forceps — a simple bedside manoeuvre that can be immediately effective
6. Haematometra (Post-abortal Syndrome)
Incidence: ~1% of surgical TOPs
After evacuation, the cervix can go into reflex spasm and close tightly (especially if cervical priming was inadequate). Meanwhile, the placental bed continues to ooze blood. With the os closed, blood accumulates inside the uterus. The uterus distends, but distension actually worsens the bleeding because:
- A distended uterus cannot contract effectively (Laplace's law — wall tension is proportional to radius; a dilated uterus needs more force to generate the same contraction pressure)
- Compressed venous drainage from the distended uterus further congests the placental bed
This creates a vicious cycle: blood accumulates → uterus distends → less contraction → more blood accumulates.
| Feature | Mechanism |
|---|---|
| Severe cramping pain within hours of procedure | Uterus contracting against a closed outflow (like trying to squeeze a balloon with the neck tied) |
| Tender, distended, boggy uterus on bimanual exam | Blood filling the cavity |
| Closed cervical os | Reflex cervical spasm |
| Minimal external vaginal bleeding (paradoxically) | The blood is trapped INSIDE — it cannot escape |
| Tachycardia, diaphoresis | Pain response ± concealed blood loss |
- Re-evacuation of the uterus — suction aspiration; as soon as the cannula enters the uterus, dark blood gushes out and the patient experiences immediate relief
- Uterotonics post-evacuation (oxytocin) to maintain contraction and prevent re-accumulation
7. Failed TOP (Continuing Pregnancy)
Incidence: 2–5% for medical TOP (first trimester); < 0.5% for surgical TOP
- Medical: The mifepristone-misoprostol regimen fails to completely detach and expel the pregnancy. The embryo remains implanted and viable. Risk factors include very early gestation ( < 6 weeks — the sac is very small and may be missed), obesity (reduced misoprostol absorption), and fibroids (altered uterine contractility).
- Surgical: The operator fails to aspirate the gestational sac — either because it is very small (early pregnancy) or because the uterus has an anomaly (e.g., one horn of a bicornuate uterus is not evacuated)
- Persistent pregnancy symptoms (nausea, breast tenderness)
- No or minimal bleeding after medical TOP
- Rising or plateauing β-hCG
- USS shows viable IUP with fetal cardiac activity
- Surgical evacuation — definitive treatment
- Counselling: The woman must be informed that if she chooses to continue the pregnancy after exposure to mifepristone, there is uncertain but possible teratogenic risk (data is limited; mifepristone is classified as a potential teratogen, though evidence of specific anomalies in continuing pregnancies is inconsistent)
The 'No Bleeding' Red Flag After Medical TOP
If a woman reports no bleeding at all after taking the medical TOP regimen, suspect failed TOP. She should be assessed urgently with serum β-hCG and USS. Do NOT assume the drugs have worked without confirmation.
8. Asherman Syndrome (Intrauterine Adhesions)
Incidence: Estimated 2–22% after surgical evacuation for miscarriage/TOP (varies by technique and number of procedures)
"Asherman" = Joseph Asherman, who described the syndrome in 1948.
The endometrium has two layers:
- Functionalis — the superficial layer that sheds during menstruation and is rebuilt each cycle
- Basalis — the deep layer that contains stem cells responsible for regenerating the functionalis
During surgical evacuation, if the basalis layer is damaged (by excessive or aggressive curettage), the regenerative capacity is lost. Instead of regrowing normal endometrium, the denuded areas on opposing uterine walls heal by forming fibrous adhesions (scar tissue bridges) across the cavity. These adhesions:
- Physically obliterate parts of the uterine cavity
- Reduce the functional endometrial surface area
- Block the internal os or tubal ostia
| Risk Factor | Why |
|---|---|
| Sharp curettage (especially repeated) | Most damaging to the basalis layer |
| Post-partum or post-abortal curettage | The post-pregnant uterus is particularly vulnerable — the endometrium is thin and the basalis is easily reached |
| Infection at time of curettage | Infected, inflamed tissue heals with more fibrosis |
| Multiple procedures | Cumulative damage |
| Feature | Mechanism |
|---|---|
| Secondary amenorrhoea [9] | Adhesions obliterate the cavity → no functionalis to shed → no menstruation despite normal ovarian function |
| Hypomenorrhoea | Partial adhesions → reduced endometrial surface → scanty periods |
| Cyclic pelvic pain (if os obstructed) | Menstrual blood formed in isolated endometrial pockets trapped behind adhesions (haematometra) |
| Infertility | No functional endometrium for implantation; adhesions may block tubal ostia |
| Recurrent miscarriage | Even if pregnancy implants, the thin, scarred endometrium cannot support it |
- Hysteroscopy (gold standard) — direct visualisation of adhesions within the uterine cavity; also therapeutic (adhesions can be divided at the same time)
- Hysterosalpingography (HSG) [13] — shows filling defects within the uterine cavity and may show blocked fallopian tubes (used for investigation of infertility and recurrent abortion) [13]
- Saline infusion sonohysterography (SIS) — saline instilled into the uterus under USS → adhesions visible as bands
- USS: May show thin endometrium, but not specific
- Hysteroscopic adhesiolysis — division of adhesions under direct vision (the treatment of choice)
- Post-operative measures to prevent re-formation:
- Intrauterine balloon catheter (Foley catheter with balloon inflated in the cavity) left for 5-7 days → acts as a physical spacer preventing the walls from re-adhering
- Exogenous oestrogen (high-dose oestradiol) for 2-3 months → stimulates endometrial regeneration over the denuded areas
- Repeat hysteroscopy to assess and divide any re-formed adhesions
Asherman Prevention — Use Suction, Not Sharp Curettage
The single most important prevention strategy is to avoid aggressive sharp curettage. Modern practice favours suction aspiration for all uterine evacuations, with sharp curettage reserved only for a light "check curette" if needed. This preserves the basalis layer and dramatically reduces Asherman risk.
9. Cervical Incompetence (Cervical Insufficiency)
If the cervix is traumatised during TOP (forceful dilation, cervical laceration), the internal os may be permanently weakened. In a subsequent pregnancy, this weakened cervix cannot withstand the increasing weight and pressure of the growing fetus → painless cervical dilation in the second trimester → preterm delivery or second-trimester miscarriage.
- More common after repeated first-trimester surgical TOPs or second-trimester D&E (which requires significant dilation)
- The association between a single, uncomplicated first-trimester TOP and cervical incompetence is debated and probably very small — but repeated procedures or traumatic procedures definitely increase risk
- Cervical cerclage — a suture placed around the cervix (usually at 12-14 weeks) to keep it closed; removed at 36-37 weeks or at onset of labour
- Progesterone supplementation — vaginal progesterone from mid-trimester to reduce preterm birth risk
10. Rh Isoimmunisation
If anti-D immunoglobulin is NOT administered to an Rh-negative woman undergoing TOP:
- Fetomaternal haemorrhage occurs during the procedure (fetal Rh-positive red cells enter maternal circulation)
- Maternal immune system recognises the D antigen as foreign → produces anti-D IgG antibodies (primary sensitisation — takes ~4-6 weeks)
- In a subsequent pregnancy with an Rh-positive fetus, these pre-formed anti-D IgG antibodies cross the placenta → bind to fetal Rh-positive red cells → opsonise them for destruction by fetal reticuloendothelial system → haemolytic disease of the fetus and newborn (HDFN):
- Fetal anaemia → high-output cardiac failure → hydrops fetalis
- Severe neonatal jaundice (unconjugated bilirubin from haemolysis) → kernicterus (bilirubin encephalopathy)
- Anti-D immunoglobulin to ALL Rh-negative women within 72 hours of TOP [2]
- This is one of the most important preventive measures in obstetric practice — failure to administer anti-D is a recognised medicolegal pitfall
11. Psychological Sequelae
- The majority of women do NOT experience clinically significant long-term psychological harm after TOP
- The best predictor of post-TOP mental health is pre-TOP mental health — women with pre-existing depression or anxiety are at higher risk of psychological distress after TOP
- Outline of emotional impact on the couple with early pregnancy losses [5] — the lecture explicitly acknowledges the emotional dimension
| Risk Factor | Why |
|---|---|
| Pre-existing mental health condition | Vulnerability to mood disturbance amplified by the experience |
| Ambivalence about the decision | Internal conflict → guilt, regret |
| Lack of social support | No one to process the experience with |
| Later gestational age | Procedure is more invasive; fetal form is more developed; more psychologically distressing |
| TOP for fetal anomaly | The pregnancy was often wanted; grief compounded by loss of the "expected" child |
| Coercion | Woman pressured into the decision by partner, family, or circumstances |
| Young age / adolescence | Developmental vulnerability |
- Pre-procedure and post-procedure non-directive counselling — essential component of care [2]
- Screening for pre-existing mental health conditions
- Referral to psychological services if distress persists
- Follow-up visit to check emotional well-being in addition to physical recovery
'Post-Abortion Syndrome' — Not a Real Diagnosis
"Post-abortion syndrome" is NOT a recognised psychiatric diagnosis in the DSM-5, ICD-11, or any major psychiatric classification. Large systematic reviews (including the Turnaway Study and the UK National Collaborating Centre for Mental Health review) consistently show that TOP is not an independent risk factor for mental health problems. Claims to the contrary are not supported by evidence and should not be propagated.
12. Venous Thromboembolism (VTE)
Pregnancy itself is a hypercoagulable state (elevated fibrinogen, factors VII, VIII, X, von Willebrand factor; decreased protein S; increased venous stasis from progesterone-mediated venous dilation and uterine compression of pelvic veins). Although TOP removes the pregnancy, the coagulable state does not immediately normalise. Additionally:
- The absolute risk of VTE after TOP is very low (< 0.05%)
- Higher risk: second-trimester procedures, prolonged immobilisation, obesity, thrombophilia, previous VTE
- Thromboprophylaxis (LMWH) is NOT routine for straightforward first-trimester TOP in low-risk women
- Consider thromboprophylaxis for: BMI > 30, previous VTE, known thrombophilia, prolonged procedure/immobilisation
| Complication | Incidence | Mechanism |
|---|---|---|
| Prolonged bleeding | Variable — may spot for 2-4 weeks | Expected; the decidua sheds gradually; only concerning if heavy or prolonged > 4 weeks |
| GI side effects | 20-30% | Misoprostol stimulates GI smooth muscle → diarrhoea, nausea, vomiting |
| Fever / rigors | 10-40% | Prostaglandin-mediated hypothalamic effect; usually transient ( < 24h); persistent fever ( > 24h) → suspect infection |
| Allergic reaction | Very rare | To mifepristone or misoprostol |
| Complication | Frequency | Severity | Prevention |
|---|---|---|---|
| Bleeding (mild-moderate) | Very common (expected) | Usually self-limiting | Uterotonics; confirm complete evacuation |
| Incomplete abortion | 2-5% (medical); < 1% (surgical) | Moderate | Inspect products; follow-up β-hCG |
| Infection / endometritis | ~3% (without Abx); < 1% (with Abx) | Moderate-severe | Prophylactic antibiotics; STI screening |
| Haematometra | ~1% | Moderate | Adequate cervical priming |
| Cervical laceration | < 1% | Low-moderate | Cervical priming |
| Uterine perforation | 1-4 per 1,000 | High (if bowel injury) | Cervical priming; experienced operator; USS guidance |
| Failed TOP | 2-5% (medical); < 0.5% (surgical) | Moderate | Follow-up confirmation |
| Asherman syndrome | 2-22% (variable) | High (fertility impact) | Suction aspiration (avoid sharp curettage) |
| Cervical incompetence | Rare | High (future pregnancies) | Cervical priming; avoid excessive dilation |
| Rh sensitisation | Preventable | High (future pregnancies) | Anti-D immunoglobulin |
| VTE | < 0.05% | High | Thromboprophylaxis in high-risk |
| Psychological distress | Variable | Low-moderate | Counselling before and after |
| Death | < 1 per 100,000 (1st trimester) | Maximum | Safe, legal, supervised care |
High Yield Summary
Immediate complications: Haemorrhage (atony, retained products, cervical laceration, perforation), uterine perforation (→ bowel injury — always laparoscopy to exclude), vasovagal reaction
Early complications: Incomplete abortion (ongoing bleeding, elevated β-hCG, USS echogenic material → re-evacuate), endometritis/septic abortion (fever, foul discharge → IV antibiotics → evacuation 1h later by experienced surgeon), haematometra (pain + distended uterus + closed os + minimal external bleeding → re-evacuate), failed TOP (no bleeding after medical TOP → USS + β-hCG → surgical completion)
Late complications: Asherman syndrome (secondary amenorrhoea, infertility — from basalis damage by curettage → prevent by using suction not sharp curettage), cervical incompetence (second-trimester loss in future — from cervical trauma), Rh isoimmunisation (preventable with anti-D), psychological sequelae (not a "syndrome" — support and counselling)
Key Management Principles:
- Perforation → STOP → laparoscopy (bowel damage risk)
- Septic abortion → IV antibiotics FIRST → evacuate ~1h later
- No products at evacuation → suspect ectopic/cornual
- All Rh-negative women → anti-D within 72h
- Prevention of Asherman → suction aspiration, avoid aggressive curettage
Active Recall - Complications of Termination of Pregnancy
References
[2] Lecture slides: GCBC-OG-Gyn Emergency_Notes to students_Sep2024.pdf; Block C - Gyanecological Emergency Notes to Students.pdf [3] Lecture slides: Block C - The woman needs that drug_ Oral contraceptives, Drugs affecting uterine motility.pdf [4] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf [5] Lecture slides: GC 223. Complications of Early Pregnancy.pdf [9] Senior notes: Maksim Medicine Notes.pdf (Secondary amenorrhoea — Asherman syndrome) [11] Senior notes: Ryan Ho Haemtology.pdf (DIC — obstetric causes including septic abortion) [13] Senior notes: Ryan Ho Diagnostic Radiology.pdf (Uterine artery embolisation; Hysterosalpingography) [14] Lecture slides: OBGYN Clinical Test By Topic.pdf (TOP exam question — uterine perforation) [15] Senior notes: Ryan Ho Haemtology.pdf (VTE risk factors — OCP, pregnancy); Ryan Ho Respiratory.pdf (PE risk factors — OCP)
High Yield Summary
Definition: TOP = deliberate ending of pregnancy before viability; legal in HK under Cap. 212 with specific conditions.
Legal Requirements (HK):
- ≤ 24 weeks; 2 doctors' opinions; approved institution; specified grounds (maternal health, fetal anomaly)
- No gestational limit if immediately necessary for maternal life/grave permanent injury
Methods:
- Medical: Mifepristone (anti-progestogen) + Misoprostol (PGE1 analogue) — works by decidual necrosis + uterine contractions
- Surgical: Vacuum aspiration (1st trimester), D&E (2nd trimester); cervical priming recommended
Key Pharmacology:
- Mifepristone → blocks progesterone → decidual necrosis, cervical softening, sensitizes myometrium to prostaglandins
- Misoprostol → PGE1 agonist → uterine contractions + cervical ripening
- Gemeprost → PGE1 (vaginal, needs cold storage)
- Oxytocin → adjunct in 2nd trimester
Pre-procedure Must-Dos:
- Confirm IUP (exclude ectopic!)
- Gestational age (USS)
- Blood group + Rh status (anti-D if Rh-negative)
- STI screening
- Counselling + consent (2 doctors)
Key Complications: Haemorrhage, incomplete abortion, uterine perforation, infection/sepsis, cervical laceration, failed TOP, Asherman syndrome
High Yield Summary
Pre-TOP DDx — The 3 Must-Excludes:
- Ectopic pregnancy — empty uterus + positive β-hCG; treat with laparoscopic salpingectomy, NOT uterine evacuation
- Molar pregnancy — snowstorm USS, very high β-hCG; requires suction evacuation + β-hCG surveillance, NOT standard medical TOP
- Cornual/interstitial pregnancy — eccentric sac; suspected if no products obtained at suction TOP
Key Principles:
- Always perform pregnancy test in any reproductive-age woman with abdominal pain
- Always perform TVUS before TOP to confirm IUP, exclude ectopic, date pregnancy
- Always inspect evacuated tissue for products of conception — absence suggests abnormal implantation site
- After TOP, differentiate complications (incomplete abortion, perforation, sepsis, haematometra, failed TOP) from non-TOP causes (ectopic, appendicitis, PID, ovarian pathology)
- Prioritise life-threatening conditions (ruptured ectopic, septic abortion, perforation) over less urgent diagnoses
High Yield Summary
Pre-TOP Investigations — The Minimum Set:
- Urine β-hCG — confirm pregnancy (negative rules out ectopic)
- TVUS — confirm IUP, site, viability, gestational age (CRL)
- FBC — baseline Hb, detect anaemia
- Blood group + Rh — anti-D if Rh-negative
- Group and save — prepare for possible haemorrhage
- STI screening or prophylactic antibiotics — prevent post-TOP infection
- Legal documentation — two doctors certify grounds; informed consent
Discriminatory Zone: β-hCG 1,000-2,000 mIU/mL — above this, IUP should be visible on TVUS. If not → suspect ectopic. BUT do not make irreversible decisions on a single value in stable patients.
Serial β-hCG (48h): Rising ≥ 66% = likely viable IUP; rising < 66% = abnormal (ectopic/failing); falling = resolving.
Post-TOP Confirmation: Inspect and send products for histology. No villi = suspect ectopic/cornual. Follow-up β-hCG to confirm resolution.
USS Landmarks: GS at 5 weeks → YS at 6 weeks (confirms IUP) → FH at 6-7 weeks (confirms viability).
High Yield Summary
Method Selection:
- ≤ 9 weeks: Medical (mifepristone 200 mg PO + misoprostol 800 μg vaginal 24-48h later) OR surgical (MVA/suction aspiration) — patient choice
- 9-14 weeks: Surgical (suction aspiration) preferred; medical also possible
- 14-24 weeks: Medical (mifepristone + repeated misoprostol/gemeprost) preferred; D&E only by experienced operator
- Molar pregnancy: Suction evacuation (NOT medical TOP)
Key Drugs:
- Mifepristone: anti-progesterone → decidual necrosis, cervical softening, prostaglandin receptor upregulation
- Misoprostol: PGE1 → uterine contractions + cervical ripening; vaginal route most effective
- Gemeprost: PGE1 pessary; needs cold storage; second-trimester use
- Oxytocin: adjunct in second trimester; ineffective alone in early pregnancy
Cervical Priming: Recommended for ALL surgical TOP; essential > 12 weeks, nulliparous, < 18 years
Perioperative Must-Dos: Prophylactic antibiotics + Anti-D (if Rh-negative) + Analgesia + Immediate contraception
Complication Management:
- No products at evacuation → suspect ectopic/cornual → urgent evaluation
- Perforation → stop procedure → laparoscopy/laparotomy (bowel injury risk)
- Septic abortion → IV antibiotics → experienced surgical evacuation ~1h after
- Haematometra → re-evacuation + uterotonics
High Yield Summary
Immediate complications: Haemorrhage (atony, retained products, cervical laceration, perforation), uterine perforation (→ bowel injury — always laparoscopy to exclude), vasovagal reaction
Early complications: Incomplete abortion (ongoing bleeding, elevated β-hCG, USS echogenic material → re-evacuate), endometritis/septic abortion (fever, foul discharge → IV antibiotics → evacuation 1h later by experienced surgeon), haematometra (pain + distended uterus + closed os + minimal external bleeding → re-evacuate), failed TOP (no bleeding after medical TOP → USS + β-hCG → surgical completion)
Late complications: Asherman syndrome (secondary amenorrhoea, infertility — from basalis damage by curettage → prevent by using suction not sharp curettage), cervical incompetence (second-trimester loss in future — from cervical trauma), Rh isoimmunisation (preventable with anti-D), psychological sequelae (not a "syndrome" — support and counselling)
Key Management Principles:
- Perforation → STOP → laparoscopy (bowel damage risk)
- Septic abortion → IV antibiotics FIRST → evacuate ~1h later
- No products at evacuation → suspect ectopic/cornual
- All Rh-negative women → anti-D within 72h
- Prevention of Asherman → suction aspiration, avoid aggressive curettage
Hyperemesis Gravidarum
Hyperemesis gravidarum is a severe form of nausea and vomiting in pregnancy that leads to dehydration, weight loss exceeding 5% of pre-pregnancy weight, and electrolyte imbalances requiring medical intervention.
Pelvic Inflammatory Disease
Pelvic inflammatory disease is an ascending polymicrobial infection of the upper female genital tract—including the uterus, fallopian tubes, and ovaries—most commonly caused by *Chlamydia trachomatis* and *Neisseria gonorrhoeae*, leading to endometritis, salpingitis, and potentially tubo-ovarian abscess.