Ovarian Torsion
Ovarian torsion is a gynecological emergency in which the ovary, often with the fallopian tube, twists on its vascular pedicle, leading to compromised blood flow and potential ischemic necrosis.
Ovarian Torsion
Ovarian torsion (also called adnexal torsion) refers to the partial or complete rotation of the ovary — and often the ipsilateral fallopian tube — around its vascular pedicle (the infundibulopelvic ligament and the utero-ovarian ligament). This rotation kinks the ovarian vessels, initially obstructing venous and lymphatic outflow (because veins are low-pressure and thin-walled, so they compress first), and eventually compromising arterial inflow. The result is progressive ischaemia and, if untreated, haemorrhagic infarction and necrosis of the ovary.
Etymology: "Torsion" derives from the Latin torquere = to twist. So ovarian torsion literally means "twisting of the ovary."
Key Concept
Ovarian torsion is a gynaecological emergency. The principle is identical to testicular torsion in males — a gonad twists on its pedicle, cutting off blood supply. Delay in surgical intervention leads to irreversible ischaemic damage and loss of the ovary. Time is gonad.
- Incidence: Ovarian torsion accounts for approximately 2.7–3% of all gynaecological emergencies [1][2]. The estimated annual incidence is ~5.9 per 100,000 women.
- Age distribution:
- Can occur at any age from neonates to postmenopausal women.
- Most common in reproductive-age women (peak 20–40 years), because this is when functional ovarian cysts and benign neoplasms are most prevalent.
- Also seen in children/adolescents — in fact, ovarian torsion is one of the most important causes of acute abdominal pain in young girls to consider.
- ~17% of cases occur in pre-menarchal or pregnant patients.
- Pregnancy: Incidence is higher during pregnancy, especially in the first trimester and early second trimester, due to corpus luteum cysts and ovarian hyperstimulation (e.g., from assisted reproductive technology). Approximately 10–20% of torsion cases occur during pregnancy.
- Laterality:
- Right side is more commonly affected than the left (~60% right vs 40% left), possibly because the sigmoid colon on the left side limits the mobility of the left ovary, and because right-sided pain may be more aggressively investigated (to rule out appendicitis) [1].
- Bilateral torsion is extremely rare (< 1%) but can occur.
Understanding the risk factors is logical: anything that enlarges the ovary or increases its mobility predisposes to torsion (a heavier or bigger ovary swings on its pedicle more easily, like a pendulum).
| Risk Factor | Mechanism |
|---|---|
| Ovarian cyst or mass (5–10 cm) | Torsion is most commonly caused by dermoid cyst (mature cystic teratoma) — because dermoid cysts contain heterogeneous material (sebum, hair, teeth) that acts as sediment, causing the ovary to be "off-balance" and prone to rolling/rotating [2][3]. Masses between 5–10 cm are the highest risk size — smaller ones don't create enough momentum, while very large masses (> 10 cm) are often less mobile because they become fixed by adhesions. |
| Benign ovarian neoplasms | Benign tumours are far more commonly associated with torsion than malignant ones, because malignant tumours tend to form adhesions to surrounding structures (cancer is "sticky"), which paradoxically protects against torsion. |
| Ovarian hyperstimulation syndrome (OHSS) | Exogenous gonadotropins (IVF treatment) cause multiple enlarged follicular cysts → heavy, swollen ovaries → prone to torsion. |
| Pregnancy | Corpus luteum cyst of pregnancy + ligamentous laxity → increased ovarian mobility. |
| Long utero-ovarian ligament / long pedicle | Greater "stalk" length means more freedom to rotate (like a ball on a long string). More common in children/adolescents whose ligaments may be relatively elongated. |
| Normal ovary (without a mass) | In children and adolescents, torsion of a normal ovary can occur because the ligaments are more lax and the ovary is more mobile before being fixed by adhesions from ovulation/inflammation. |
| Previous pelvic surgery / tubal ligation | Can alter the normal anatomical fixation of the adnexa. |
| Physical activity / sudden body movements | Sudden onset of severe abdominal pain during agitating movement (e.g., exercise) [4] — abrupt movements can initiate the twisting. |
High Yield – Dermoid Cysts and Torsion
Torsion → most common by dermoid cyst (have sediment so keeps rolling) [3]. The heterogeneous content (fat, hair, teeth) inside dermoid cysts creates an eccentric centre of gravity, making the ovary inherently unstable and prone to rotating on its pedicle — like a top-heavy ball.
4. Anatomy and Function (Relevant to Torsion)
To understand torsion, you must know the ovarian "pedicle" — the structures that suspend the ovary and carry its blood supply:
-
Infundibulopelvic ligament (suspensory ligament of the ovary)
- Runs from the ovary to the lateral pelvic wall.
- Contains the ovarian artery (branch of the aorta), ovarian vein (drains to IVC on right, left renal vein on left), and lymphatics.
- This is the primary vascular supply to the ovary.
-
Utero-ovarian ligament (ovarian ligament / proper ligament of the ovary)
- Runs from the medial pole of the ovary to the uterine cornu.
- Contains the ovarian branch of the uterine artery (an anastomotic supply from the uterine artery via the broad ligament).
- This provides a secondary blood supply.
-
Mesovarium
- The posterior leaf of the broad ligament that attaches the ovary to the broad ligament.
- Through the mesovarium, vessels from both the infundibulopelvic ligament and the utero-ovarian ligament enter the ovarian hilum.
-
Tubo-ovarian ligament (fimbria ovarica)
- Connects the fimbriated end of the fallopian tube to the ovary.
- This is why when the ovary torts, the tube often goes with it.
Why does the ovary tort? The ovary is relatively mobile because it is only suspended by these ligamentous structures (unlike the uterus, which is held by the cardinal and uterosacral ligaments). If something enlarges the ovary (e.g., a cyst), it becomes heavier and can rotate on the axis formed by the infundibulopelvic ligament and utero-ovarian ligament — like a pendulum swinging and flipping.
The ovary has a dual blood supply: the ovarian artery (via the infundibulopelvic ligament) and the ovarian branch of the uterine artery (via the utero-ovarian ligament). This dual supply has several important clinical implications:
- In partial torsion, one vessel may remain patent, allowing some perfusion to continue. This is why Doppler flow may still be detectable even in a torted ovary — the presence of Doppler flow does NOT exclude torsion.
- The dual supply also provides collateral flow, which may allow the ovary to survive longer than the testis in torsion (testis has a single arterial supply via the testicular artery).
In the majority (60–80%) of cases, the fallopian tube torts together with the ovary because of the tubo-ovarian ligament connecting them. This is why the term "adnexal torsion" is often more accurate than "ovarian torsion." Isolated tubal torsion is rare but can occur.
5. Aetiology (with Focus on Hong Kong)
The aetiology of ovarian torsion is essentially the aetiology of the underlying ovarian pathology that predisposes to torsion:
| Pathology | Frequency | Notes |
|---|---|---|
| Mature cystic teratoma (dermoid cyst) | Most common cause of torsion (~30–40% of torsion cases) | Sebum and hair found inside the cyst [1]. Heterogeneous content → eccentric weight → prone to rolling. Most common benign ovarian tumour in reproductive age. |
| Functional cysts (follicular / corpus luteum) | Very common | Especially in reproductive-age women. Corpus luteum cysts are common in early pregnancy. |
| Serous/mucinous cystadenoma | Common | Large benign cysts that enlarge the ovary. |
| Paraovarian cysts | Occasional | Arise from the broad ligament, can cause adnexal torsion. |
| Endometrioma | Less common | Endometriotic cysts, though adhesions from endometriosis may somewhat protect against torsion. Dysmenorrhoea (endometriosis) [5]. |
| OHSS-related enlarged ovaries | Context-dependent | Relevant in HK given the high utilisation of IVF/ART services. |
| Normal ovary (no mass) | ~20–30% (especially in children) | Paediatric/adolescent torsion may occur in normal ovaries. |
| Malignant ovarian tumours | Rare cause of torsion (< 5%) | Malignant tumours form adhesions → paradoxically protective against torsion. |
- Dermoid cysts are the most common benign ovarian neoplasm in young women in Hong Kong and are the leading pathological cause of ovarian torsion locally.
- IVF/ART usage is increasing in Hong Kong due to delayed childbearing (average age at first birth ~32 years), increasing the population at risk for OHSS-related torsion.
- Endometriosis is common in Hong Kong (estimated 10% of reproductive-age women), contributing to ovarian cysts (endometriomas).
6. Pathophysiology
The pathophysiology of ovarian torsion follows a predictable sequence once rotation occurs:
Step-by-step explanation:
- Rotation occurs — the ovary (and usually the fallopian tube) twists on the infundibulopelvic and utero-ovarian ligaments.
- Venous and lymphatic obstruction first — because veins and lymphatics are thin-walled and low-pressure, they are compressed before arteries. This causes venous congestion and oedema of the ovary.
- This is why the ovary becomes massively swollen and oedematous on imaging and at surgery.
- Arterial inflow continues initially — blood keeps flowing INTO the ovary but cannot get OUT. This causes the ovary to become engorged with blood (haemorrhagic congestion).
- This is why Doppler may initially still show arterial flow — leading to false negatives.
- Progressive oedema increases tissue pressure → eventually exceeds arterial pressure → arterial occlusion → true ischaemia.
- Ischaemic necrosis — if not relieved, the ovary undergoes haemorrhagic infarction (the trapped blood has nowhere to go).
- If necrotic ovary is left in situ → infection, abscess formation, peritonitis, sepsis. There is also a theoretical (though debated) risk of thromboembolism from the thrombosed ovarian vein.
The ovary can undergo intermittent torsion and detorsion — the ovary twists partially, causing temporary pain, then untwists spontaneously, with resolution of symptoms. This explains:
- Recurrent episodes of lower abdominal pain that resolve spontaneously.
- Intermittent LLQ pain as described in the case of ovarian teratoma with recurrent torsion/detorsion [6].
- The clinical challenge: patients may present multiple times with "resolved" pain before the definitive torsion event occurs.
- Torsion is described in terms of number of turns (e.g., torsion for 1.5 turn as described in the lecture case [1]).
- Greater degrees of torsion → more complete vascular compromise → worse prognosis for ovarian viability.
- Even a single 360° turn can cause complete vascular occlusion.
Why Veins Compress Before Arteries
Think of it like squeezing a garden hose. A high-pressure fire hose (artery) requires much more force to compress than a thin, floppy soaker hose (vein). This venous > arterial compression sequence is the same principle seen in testicular torsion, compartment syndrome, and ovarian torsion.
7. Classification
| Type | Description |
|---|---|
| Ovarian torsion | Ovary alone torts (less common in isolation) |
| Adnexal torsion | Ovary + fallopian tube tort together (most common pattern, ~60–80%) |
| Isolated tubal torsion | Fallopian tube torts without the ovary (rare) |
| Type | Description |
|---|---|
| Complete torsion | Full rotation with complete vascular occlusion |
| Partial/Incomplete torsion | Partial rotation; venous congestion but preserved arterial flow initially |
| Intermittent torsion-detorsion | Recurrent partial torsion that spontaneously resolves (as in dermoid cysts) [6] |
| Category | Examples |
|---|---|
| Cyst-associated torsion | Dermoid, functional cyst, cystadenoma, endometrioma |
| Mass-associated torsion | Solid benign tumours (fibroma, thecoma) |
| Normal ovary torsion | Especially in paediatric patients |
| OHSS-associated torsion | Post-IVF/ART |
8. Clinical Features
| Symptom | Pathophysiological Basis |
|---|---|
| Sudden onset of severe unilateral lower abdominal/pelvic pain [4][5] | The acute twist causes immediate stretching of the ovarian capsule (visceral peritoneum) and ischaemia of the ovarian tissue. Visceral pain from the ovary is referred to the ipsilateral iliac fossa via the T10–L1 dermatomes (ovarian nerve supply from the ovarian plexus, derived from the aortic plexus). |
| Pain during agitating movement (e.g., exercise) [4] | Sudden movement can initiate or worsen the torsion. Analogous to testicular torsion occurring with physical exertion. |
| Colicky/intermittent pain (in partial torsion) | Intermittent LLQ pain [6] — in partial torsion-detorsion, the ovary repeatedly twists and untwists, causing episodic ischaemic pain that resolves when the ovary untwists and blood flow resumes. |
| Nausea and vomiting | Autonomic response to severe visceral pain. Visceral pain fibres travel with sympathetic afferents → stimulate the area postrema and vomiting centre in the brainstem. Same mechanism as nausea/vomiting in testicular torsion, renal colic, and bowel obstruction. |
| Radiation to groin, flank, or back | Referred pain along the distribution of the ovarian nerve plexus (T10–L1 dermatomes, overlapping with renal and ureteric innervation — hence pain can mimic renal colic). |
| Pain that worsens progressively | Initially venous congestion → then ischaemia → then infarction. Each stage produces more intense pain as tissue damage escalates. |
| Abdominal distension [5] | Due to the cyst itself, reactive free fluid from peritoneal irritation, or paralytic ileus from peritoneal inflammation. |
| Pressure symptoms (urinary/bowel) [5] | Large ovarian cyst compressing adjacent bladder or rectum, causing urinary frequency/urgency or constipation/tenesmus. |
| Absence of vaginal bleeding | This is an important negative feature that helps distinguish torsion from ruptured ectopic pregnancy or miscarriage (which typically present with vaginal bleeding). |
| Sign | Pathophysiological Basis |
|---|---|
| Vital signs: tachycardia, may have low-grade fever [5] | Tachycardia reflects pain and stress response (sympathetic activation). Low-grade fever (< 38.5°C) occurs due to tissue necrosis/inflammation. High fever (> 38.5°C) suggests established necrosis or superimposed infection. |
| Lower abdominal tenderness with or without guarding [4] | Peritoneal irritation from the congested, oedematous, or necrotic ovary. Initially, tenderness is localised. Guarding (involuntary contraction of abdominal muscles) indicates parietal peritoneal inflammation. |
| Rebound tenderness (if advanced) | Indicates peritonitis — the inflamed/necrotic ovary irritates the parietal peritoneum. |
| Tender adnexal mass on bimanual pelvic examination | The swollen, congested, torted ovary is palpable as a ~6 cm cystic mass felt in the anterior fornix, tender & slightly mobile only [1]. Limited mobility because the torted pedicle restricts movement. |
| Unilateral adnexal tenderness | Ovary is exquisitely tender because of ischaemia and capsular distension. |
| Cervical excitation tenderness (variable) | In the lecture case, cervix — no excitation tenderness was noted [1]. Cervical motion tenderness is more classically associated with PID or ectopic pregnancy, but may occasionally be present in torsion if there is significant peritoneal irritation. Its absence helps distinguish torsion from PID. |
| Mass usually separated from uterus [5] | The ovary is anatomically separate from the uterus (connected only by the utero-ovarian ligament), so the mass is typically felt lateral and separate from the uterus on bimanual examination — unlike uterine fibroids, which move with the uterus. |
| Less mobile if adhesions (endometriosis) [5] | If there is underlying endometriosis or prior surgery, adhesions limit the mobility of the mass on examination. |
| Reduced bowel sounds | Peritoneal irritation from the torted ovary causes a reflexive paralytic ileus, reducing bowel sounds. |
| Signs of intra-abdominal bleeding / haemodynamic instability [4] | If the torted ovary undergoes haemorrhagic infarction and ruptures, there can be significant haemoperitoneum → signs of hypovolemic shock (tachycardia, hypotension, pallor, cold extremities). |
| Feature | Ovarian Torsion | Ruptured Ectopic | PID | Appendicitis |
|---|---|---|---|---|
| Pain onset | Sudden, severe | Sudden, severe | Gradual | Gradual (migrates) |
| Vaginal bleeding | Usually absent | Present | Discharge, not blood | Absent |
| Fever | Low-grade (late) | Usually absent | High (38–39.5°C) | Moderate |
| βhCG | Negative (unless pregnant) | Positive | Negative | Negative |
| Cervical excitation | Usually absent | Present | Present (Chandelier sign) | Absent |
| Nausea/vomiting | Common | Variable | Uncommon | Common |
| Adnexal mass | Present | ± present | Bilateral tenderness | Absent |
Clinical Pearl – Why Pain Is Sudden
Unlike PID (which has gradual onset from infection spreading through the tubes), ovarian torsion causes sudden pain because it is a mechanical event — the ovary physically rotates, acutely stretching the capsule and occluding vessels. This sudden onset is your best clinical clue.
Important – Do NOT Rely on Doppler to Rule Out Torsion
A common mistake is assuming that the presence of arterial flow on Doppler ultrasound rules out torsion. It does NOT. Because the dual blood supply may allow some arterial flow to persist even in partial torsion, and because veins compress before arteries, you can have a torted ovary WITH Doppler flow. Satisfactory perfusion of left ovary noted after detorsion [1] — implying there was likely reduced perfusion before detorsion. The diagnosis is clinical + surgical; Doppler is supportive but not definitive.
The lecture presents a classic case illustrating ovarian torsion [1]:
- Patient: Young woman with acute lower abdominal pain (likely left-sided)
- Examination: A ~6 cm cystic mass felt in the anterior fornix; tender & slightly mobile only
- Rectal exam: Cervix — no excitation tenderness; uterus — ill defined; both lateral adnexae found clear (because the mass was anterior, not lateral)
- USG (Pelvis): Normal sized retroverted uterus. A complex cystic lesion (6 cm × 5.8 cm × 6.2 cm) at left antero-lateral aspect of uterus. Heteroechogenic content. Right ovary normal. Left ovary not seen. No fluid at POD. Impression: Dermoid cyst.
- Intraoperative findings: A 7 cm left ovarian cyst with torsion for 1.5 turn. Uterus and right ovary normal. Satisfactory perfusion of left ovary noted after detorsion. Cystectomy performed. Sebum and hair found inside the cyst.
- Pathology: Mature cystic teratoma of left ovary
This case perfectly illustrates the classic scenario: a dermoid cyst (mature cystic teratoma) → torsion → cystectomy with ovarian conservation after confirming viability.
High Yield Summary
- Ovarian torsion = gynaecological emergency — partial or complete rotation of the ovary on its vascular pedicle → vascular compromise → ischaemia → infarction.
- Most common predisposing lesion = dermoid cyst (mature cystic teratoma) — heterogeneous content (sebum, hair, teeth) makes it prone to rolling.
- Veins compress before arteries → venous congestion → oedema → then arterial occlusion → haemorrhagic infarction. This is why Doppler flow may be preserved early and DOES NOT rule out torsion.
- Clinical presentation: Sudden severe unilateral lower abdominal pain ± nausea/vomiting, tender adnexal mass, often during or after physical activity. Low-grade fever if necrosis. No vaginal bleeding (distinguishes from ectopic pregnancy).
- Right side > left (sigmoid colon restricts left ovary mobility).
- Risk factors: Ovarian cyst 5–10 cm (especially dermoid), OHSS, pregnancy, long pedicle, normal ovary in children.
- Benign tumours cause torsion more than malignant — malignant tumours form adhesions that prevent rotation.
- Intermittent torsion-detorsion can occur, causing recurrent episodes of lower abdominal pain.
- "Left ovary not seen" on USS with an ipsilateral cystic mass is a clue — the cyst IS the torted ovary.
- Key differential diagnoses: Ruptured ectopic pregnancy, PID, appendicitis, ruptured ovarian cyst, endometriosis.
Active Recall - Ovarian Torsion (Definition, Epidemiology, Anatomy, Aetiology, Pathophysiology, Clinical Features)
[1] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf (Cards 13–19) [2] Lecture slides: Block C - O&G Theme Case 3.pdf (p4) [3] Lecture slides: Block C - O&G Theme Case 3.pdf (p4 — "Torsion → most common by dermoid cyst (have sediment so keeps rolling)") [4] Senior notes: Ryan Ho Fundamentals.pdf (p273 — "Torsion/ruptured of ovarian cyst") [5] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p12, p20) [6] Senior notes: Ryan Ho Radiology.pdf (p33 — "ovarian teratoma with recurrent torsion/detorsion")
Differential Diagnosis of Ovarian Torsion
The cardinal teaching point from the lecture slides is this: the most important part 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 [1]. In practice, a woman presenting with acute lower abdominal pain requires you to think systematically across organ systems — gynaecological, gastrointestinal, and urological — and then triage by urgency.
The core clinical scenario is: a reproductive-age woman with sudden-onset severe unilateral lower abdominal/pelvic pain ± nausea/vomiting ± adnexal mass. Your job is to figure out whether this is ovarian torsion versus the other diagnoses that can mimic it.
First Principles – Why Is the DDx Broad?
The pelvis is a crowded space. The ovary sits immediately adjacent to the fallopian tube, uterus, ureter, appendix (on the right), sigmoid colon (on the left), and bladder. All of these structures share overlapping visceral innervation (T10–L1 sympathetic afferents). This is why pain from the ovary, ureter, appendix, and tube all present similarly — your nervous system genuinely cannot tell the difference at first. The DDx is therefore based on associated features (vaginal bleeding? discharge? urinary symptoms? pregnancy status?) that help you localise the source.
Detailed Differential Diagnoses
A. Gynaecological Causes (Priority DDx)
These are the most important differentials to consider and exclude [7][8]. The lecture explicitly states: Exclude ovarian cyst complications, pregnancy complications as urgent priorities [7].
Ectopic pregnancy [4][9] — this is the most dangerous DDx and must be excluded first in any woman of reproductive age with acute lower abdominal pain.
| Feature | Ectopic Pregnancy | Ovarian Torsion |
|---|---|---|
| βhCG | Positive | Negative (unless incidentally pregnant) |
| Vaginal bleeding | Present (typically dark, scanty PV bleeding) | Usually absent |
| Pain character | Sudden severe lower abdominal pain, may generalise if ruptured | Sudden severe unilateral pain |
| Preceding symptoms | S/S of pregnancy (morning sickness, amenorrhoea, breast swelling, +ve test) [9]; preceded by a few days of mild abdominal pain | None typically |
| Cervical excitation | Positive | Usually negative [1] |
| Shoulder tip pain | Present if blood collects beneath the diaphragm [9] (phrenic nerve irritation, C3–C5 dermatome) | Absent |
| Shock | Signs of hypovolaemia (tachycardia, pale, sweating, postural hypotension) [9] if ruptured | Rare unless haemorrhagic infarction with rupture |
| Risk factors | History of PID, fertility problems, IUD, previous ectopic | Ovarian cyst, dermoid |
Why is βhCG the single most important first-line test? Because a negative βhCG immediately eliminates all pregnancy-related causes from your differential. This is why girls: ask LMP, order PT (pregnancy test) [10] is drilled into surgical teaching.
Ovarian cyst complications — rupture [3][11] is the other major acute complication of an ovarian cyst alongside torsion.
| Feature | Ruptured Cyst | Ovarian Torsion |
|---|---|---|
| Onset | Sudden onset, often begins with strenuous physical activity [11] | Sudden onset, often with agitating movement |
| Pain character | Sudden sharp pain that may then improve (once the cyst ruptures, the capsular tension is released) | Pain is persistent and worsening (ongoing ischaemia) |
| Free fluid | Usually present on USS (leaked cyst contents / blood in POD) | Minimal or absent early; may be present later |
| Adnexal mass | May collapse/disappear after rupture | Persistent, enlarged, oedematous ovary |
| Peritonism | Especially painful if dermoid cyst rupture [11] (sebaceous contents cause chemical peritonitis) | Present if necrosis develops |
| Vaginal bleeding | May be associated with light vaginal bleeding [11] | Absent |
| Doppler | Normal flow in remaining ovary | Absent or reduced flow (though can be falsely normal) |
Key distinction: In rupture, the pain often peaks then partially improves (pressure is released). In torsion, the pain progressively worsens (ongoing ischaemia escalates).
Ovarian cyst acute complications have 3 classical forms, all will present with abdominal pain → torsion, haemorrhage, rupture [3].
- Haemorrhage into an ovarian cyst (without rupture) causes sudden expansion of the cyst → capsular distension → acute pain.
- The cyst remains intact (no free fluid), but the ovary is enlarged and tender.
- USS shows internal echoes within the cyst (blood clot = "reticular" or "cobweb" pattern on ultrasound).
- Important distinction from torsion: Doppler flow is preserved (the vessels are not twisted, just the cyst is bleeding internally).
PID [4] — salpingitis and associated infection of the supporting tissues around the adnexa.
| Feature | PID | Ovarian Torsion |
|---|---|---|
| Onset | Gradual onset of constant lower abdominal pain [4] | Sudden onset |
| Fever | High fever (38–39.5°C) [4] | Low-grade or absent early |
| Vaginal discharge | Preceded by purulent yellow-white vaginal discharge [4] | Absent |
| Cervical excitation | Chandelier sign positive [4] (cervical motion tenderness so painful the patient "reaches for the chandelier") | Usually negative |
| Bilaterality | Often bilateral but may be asymmetric [4] | Unilateral |
| Dyspareunia | Often a/w dyspareunia [4] | Not a feature |
| History | Sexually active, Hx of previous gyne procedures, IUD, or STDs [4] | Ovarian cyst history |
| N/V | No N/V or changes in bowel habits [4] | N/V common (autonomic response) |
| Pain location | Usually lower and nearer to midline compared to appendicitis [4] | Lateral, in iliac fossa |
Why no N/V in PID but present in torsion? PID is an inflammatory/infectious process with gradual onset — the autonomic nervous system is not acutely overwhelmed. Torsion produces sudden, intense visceral ischaemic pain that triggers the vagal reflex → nausea/vomiting (same reason you vomit with testicular torsion or renal colic).
Mittelschmerz: mid-cycle lower abdominal/pelvic pain due to rupture of follicular cyst and bleeding → irritate peritoneum [11].
- "Mittel" = middle (German), "schmerz" = pain. Literally "middle pain" — occurring mid-cycle at ovulation (~day 14).
- Caused by physiological rupture of the Graafian follicle during ovulation → small amount of follicular fluid ± blood irritates the peritoneum → brief, self-limiting pain.
- Key distinction: Timing correlates with mid-cycle, pain is typically mild and self-limiting (resolves within hours to 1–2 days), and there is no adnexal mass.
- Can mimic torsion or appendicitis if on the right side.
- Dysmenorrhoea (endometriosis) [5] — chronic cyclic pelvic pain.
- Chronic ovarian cyst pain also possible → endometriotic cyst [3].
- Endometriomas ("chocolate cysts") can rupture, causing sudden chemical peritonitis (dark, old blood spills into the peritoneum).
- Key distinction from torsion: history of chronic dysmenorrhoea, dyspareunia, cyclical pain. Endometriomas are usually associated with adhesions → less mobile if adhesions, endometriosis [5], which actually reduces risk of torsion (but doesn't eliminate it).
Degeneration of fibroid → outgrowing blood supply and becoming necrotic [3]. This is analogous to torsion of the ovary — a pedunculated fibroid twists on its stalk, cutting off its blood supply.
| Feature | Fibroid Degeneration / Torsion | Ovarian Torsion |
|---|---|---|
| Mass | Arises from the uterus; moves WITH the uterus on bimanual examination | Usually separated from uterus [5] |
| Known history | Often known fibroids; menorrhagia | Known ovarian cyst |
| Pain | Acute if torsion of pedunculated fibroid; subacute if red degeneration | Acute, sudden |
| Pregnancy | Red / haemorrhagic degeneration during pregnancy [3] | Torsion can also occur in pregnancy |
How to distinguish? On bimanual examination, a fibroid is continuous with the uterus (you cannot separate it), while an ovarian cyst is separate from the uterus (you can feel a cleavage plane between them). USS confirms the organ of origin.
B. Gastrointestinal Causes
This is the most important non-gynaecological DDx, especially for right-sided ovarian torsion [10][11].
| Feature | Appendicitis | Ovarian Torsion |
|---|---|---|
| Pain migration | Classical: periumbilical → RLQ over 12–24h [10] | No migration; sudden onset in iliac fossa |
| Anorexia | Prominent (almost always present) | Variable |
| Fever | Low-grade initially | Low-grade or absent early |
| McBurney's point | Maximum tenderness at McBurney's point [10] | Tenderness more medial/inferior (pelvic) |
| Rovsing's sign | Positive | Negative |
| Psoas/Obturator signs | May be positive (retrocaecal or pelvic appendix) [10] | Negative |
| Vaginal exam | Usually normal | Tender adnexal mass |
| βhCG | Negative | Negative |
Differential diagnoses in adult females: consider pelvic causes. Should ALWAYS take a full gynaecological Hx, esp menstrual cycle, vaginal D/C and possible pregnancy [11]. This is a critical clinical teaching point — any young woman with RLQ pain needs gynae causes excluded.
- More relevant for left-sided ovarian torsion DDx (both cause LLQ pain).
- Diverticular disease is almost exclusively in sigmoid colon (95%) in Caucasians but more commonly to be in Rt colon in Asians [4] — important Hong Kong-specific point.
- Key distinction: older age group (usually > 50), history of constipation/altered bowel habit, CT shows diverticular inflammation with pericolic fat stranding, no adnexal mass.
- Inflammation of mesenteric lymph nodes, often following a viral illness prodrome [10].
- More common in children/adolescents.
- Can mimic both appendicitis and ovarian torsion.
- USG shows mesenteric lymphadenopathy without appendiceal or ovarian abnormality.
- Meckel's diverticulitis: CT abdomen [10] — right-sided pain, can mimic appendicitis or right ovarian torsion.
- Bowel obstruction: colicky, intermittent pain with distension, vomiting, constipation — different character from the constant worsening pain of torsion.
C. Urological Causes
Ureteric colic: colicky pain typically waxes and wanes, each episode lasting 20–60 min [11].
| Feature | Ureteric Colic | Ovarian Torsion |
|---|---|---|
| Pain character | Severe, gripping true colic with pain-free remissions [9] | Constant, worsening |
| Radiation | From renal angle, parallel to inguinal ligament into groin [9] | Ipsilateral iliac fossa, may radiate to groin |
| Behaviour | Patient rolling around bed or walking around [9] (restless) | Patient lies still (peritonism) |
| Haematuria | Gross or microscopic haematuria [9] | Absent |
| Autonomic symptoms | Sweating, N/V [9] | N/V present |
| Adnexal mass | Absent | Present |
Key distinction: Colicky pain with pain-free intervals is classic for ureteric colic. Torsion pain is constant and worsening. Also, the restlessness of renal colic (patient cannot stay still) contrasts with the stillness of peritonitis (any movement worsens parietal peritoneal pain).
Right pyelonephritis: preceded by irritative urinary symptoms (frequency, urgency); associated with loin tenderness, high fever ( > 39°C), rigors, pyuria [11].
- Key distinction: dysuria, frequency, urgency, loin tenderness, pyuria on urinalysis. These urinary symptoms are absent in ovarian torsion.
- Fever is typically higher (> 39°C with rigors) compared to the low-grade fever of torsion.
If βhCG is positive, the differential shifts entirely:
| Diagnosis | Key Features |
|---|---|
| Ruptured ectopic pregnancy | Most urgent — may require straight laparotomy [7]. Acute pain, vaginal bleeding, shock, positive βhCG. |
| Miscarriage (inevitable/incomplete) [3] | Associated symptoms → leaking sensation (liquor), per-vaginal bleeding [3]. Positive βhCG. Cervical os open on speculum. |
| Corpus luteum cyst complications in pregnancy | Torsion or rupture of corpus luteum cyst. First trimester. Positive βhCG but intrauterine pregnancy confirmed on USS. |
| Red degeneration of fibroid in pregnancy [3] | Subacute pain, known fibroids, second/third trimester. Positive βhCG with confirmed IUP. |
Attend patients who need URGENT management: Shock, severe pain (peritoneal signs). May require straight laparotomy [7].
| Priority | Diagnosis | Reason |
|---|---|---|
| 1 (Immediate) | Ruptured ectopic pregnancy | Haemodynamic instability; life-threatening haemorrhage |
| 2 (Urgent) | Ovarian torsion | Gonadal ischaemia; irreversible damage if delayed |
| 3 (Urgent) | Acute appendicitis (complicated) | Risk of perforation → peritonitis |
| 4 (Semi-urgent) | Ruptured ovarian cyst with haemoperitoneum | May need surgical haemostasis |
| 5 (Semi-urgent) | Tubo-ovarian abscess | Requires antibiotics ± drainage |
| 6 (Less urgent) | Ureteric colic, UTI, Mittelschmerz | Painful but not immediately life/organ-threatening |
These questions help you narrow the DDx efficiently:
| Question | What It Rules In/Out |
|---|---|
| "When was your last menstrual period?" | Pregnancy (ectopic), Mittelschmerz (mid-cycle) |
| "Could you be pregnant?" + βhCG | ALWAYS ask; ALWAYS test [10][11] |
| "Any vaginal bleeding or discharge?" | Ectopic (bleeding), PID (discharge), miscarriage (bleeding) |
| "Was the pain sudden or gradual?" | Sudden → torsion, rupture, ectopic. Gradual → PID, appendicitis |
| "Any nausea/vomiting?" | Torsion (yes), PID (no) [4], appendicitis (yes) |
| "Any urinary symptoms?" | UTI, pyelonephritis, ureteric colic |
| "Any known ovarian cysts?" | Strongly suggests cyst complication |
| "Any fever?" | High fever → PID, appendicitis, pyelonephritis. Low-grade → torsion (late) |
| "Does the pain come and go with pain-free intervals?" | Colicky → ureteric colic. Constant worsening → torsion |
| Diagnosis | Onset | βhCG | PV Bleed | Discharge | Fever | N/V | Cervical Excitation | Adnexal Mass |
|---|---|---|---|---|---|---|---|---|
| Ovarian torsion | Sudden | − | − | − | Low/absent | ++ | − | + |
| Ruptured ectopic | Sudden | + | + | − | − | ± | + | ± |
| Ruptured ovarian cyst | Sudden | − | ± | − | − | ± | − | ± (collapsed) |
| Haemorrhagic cyst | Sudden | − | − | − | − | ± | − | + |
| PID | Gradual | − | − | ++ | +++ | − | +++ | ± bilateral |
| Appendicitis | Migratory | − | − | − | + | + | − | − |
| Ureteric colic | Sudden colicky | − | − | − | − | + | − | − |
| Mittelschmerz | Mid-cycle | − | − | − | − | − | − | − |
| Degenerating fibroid | Subacute | −/+ | − | − | ± | ± | − | + (uterine) |
High Yield Summary – Differential Diagnosis of Ovarian Torsion
- βhCG is the single most important first test — it immediately dichotomises your DDx into pregnant vs non-pregnant causes.
- Ruptured ectopic pregnancy is the most dangerous mimic — must be excluded first in any reproductive-age woman with acute lower abdominal pain.
- Ovarian cyst acute complications have 3 classical forms: torsion, haemorrhage, rupture — all present with sudden pain but differ in trajectory (torsion worsens; rupture may improve).
- PID is gradual onset, bilateral, with discharge and high fever — contrasts sharply with the sudden, unilateral, dry presentation of torsion.
- Appendicitis is the most important non-gynae DDx for right-sided torsion — distinguished by pain migration (periumbilical → RLQ), anorexia, and absence of adnexal mass.
- Ureteric colic has colicky pain with pain-free intervals and haematuria — torsion has constant, worsening pain.
- Always take a full gynaecological history in any woman with lower abdominal pain — including LMP, vaginal discharge, pregnancy possibility, sexual history.
- Prioritise by urgency: shock and peritoneal signs may require straight laparotomy.
Active Recall - Differential Diagnosis of Ovarian Torsion
References
[1] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf (p1) [3] Lecture slides: Block C - O&G Theme Case 3.pdf (p4) [4] Senior notes: Ryan Ho Fundamentals.pdf (p273) [5] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p12, p20) [7] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p24) [8] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p71) [9] Senior notes: Ryan Ho GI.pdf (p100) [10] Senior notes: Maksim Surgery Notes.pdf (p89, p335–336) [11] Senior notes: Ryan Ho GI.pdf (p151)
Diagnostic Criteria, Algorithm, and Investigations for Ovarian Torsion
Unlike conditions such as rheumatic fever (Jones criteria) or SLE (SLICC criteria), ovarian torsion has no validated, universally accepted diagnostic criteria or scoring system. This is a critical concept to understand from first principles:
- Ovarian torsion is a surgical diagnosis — the definitive diagnosis is made intraoperatively when you directly visualise the twisted pedicle.
- All pre-operative assessments (history, examination, imaging) are supportive but not definitive. The clinical picture + imaging findings together generate a high index of suspicion that justifies urgent surgical exploration.
- This is analogous to testicular torsion, where Doppler USG cannot rule out torsion [10] and urgent exploration is indicated regardless [14].
The Golden Rule
Do NOT wait for a definitive imaging diagnosis before proceeding to surgery. If the clinical picture is strongly suggestive of ovarian torsion, proceed to urgent surgical exploration. Delays waiting for imaging increase ischaemia time and reduce the chance of ovarian salvage. The diagnosis is confirmed on the operating table.
While there are no formal criteria, the diagnosis is supported by a constellation of findings:
| Domain | Findings Supporting Ovarian Torsion |
|---|---|
| History | Sudden-onset severe unilateral lower abdominal/pelvic pain ± nausea/vomiting; known ovarian cyst; pain during physical activity; intermittent prior episodes (torsion-detorsion) |
| Examination | Unilateral adnexal tenderness; palpable tender adnexal mass; peritoneal signs (guarding, rebound); vital signs if in pain [5]; usually separated from uterus [5] |
| Bedside tests | Negative βhCG (excludes pregnancy-related causes); urinalysis negative (excludes urological causes) |
| Ultrasound | Enlarged oedematous ovary; underlying cyst/mass; whirlpool sign on Doppler; reduced or absent ovarian blood flow; free fluid |
| Intraoperative | Torsion of the stalk / infundibulopelvic ligament [15] — direct visualisation of the twisted pedicle is the definitive diagnosis |
Investigation Modalities — Detailed
1. Bedside Investigations
- Why first? Girls: ask LMP, order PT [10]. A positive βhCG completely redirects your differential to pregnancy-related causes (ectopic pregnancy, miscarriage). A negative result allows you to focus on non-pregnant gynaecological and surgical causes.
- Serum βhCG is more sensitive than urine and is used when urine is equivocal or in early pregnancy (serum can detect βhCG at ~5 mIU/mL vs urine at ~20–25 mIU/mL).
- Key point: Ovarian torsion can occur IN pregnancy (especially first trimester due to corpus luteum cysts), so a positive βhCG does NOT exclude torsion — it just adds pregnancy complications to the DDx.
- Vital signs if in pain [5] — tachycardia (pain/stress response), blood pressure (haemodynamic stability), temperature (low-grade fever suggests necrosis; high fever suggests PID or appendicitis).
| Test | Purpose and Interpretation |
|---|---|
| CBC | WBC for infection (inflammatory source may cause left shift on differential) [12][13]. Mild leukocytosis (10–15 × 10⁹/L) is common in torsion due to tissue stress/necrosis. Markedly elevated WBC ( > 16) may suggest gangrenous/necrotic ovary. Normal WBC does NOT exclude torsion (same principle as appendicitis). Hb to assess for anaemia if haemoperitoneum suspected. |
| CRP | Non-specific inflammatory marker. Elevated in torsion with necrosis, but also in PID, appendicitis. Helps track inflammatory response but not diagnostic in isolation. |
| Coagulation profile | Pre-operative workup — clotting profile, T/S for surgery [12][13]. |
| Group and Save / Crossmatch | Pre-operative — in case of haemorrhage during surgery or if ruptured cyst with haemoperitoneum. |
| RFT | Hydration status; Cr → suitability of contrast scans [12][13]. Dehydration from vomiting. |
| LFT | Usually normal; baseline pre-operative assessment. |
| Serum βhCG | Urine pregnancy test → ectopic pregnancy [12][13]. If urine test equivocal. |
| Lactate / ABG | Metabolic acidosis, ↑lactate → intestinal ischaemia [12][13]. In severe cases with necrotic ovary and peritonitis, lactate may be elevated reflecting tissue ischaemia, though this is not specific to ovarian torsion. |
Bloods Are Supportive, Not Diagnostic
No single blood test can diagnose or exclude ovarian torsion. Bloods serve three purposes: (1) exclude other diagnoses (βhCG, urinalysis), (2) assess severity/complications (WBC, CRP, lactate), and (3) pre-operative preparation (group and save, coagulation, RFT).
| Marker | Role |
|---|---|
| CA125 | CA125 and other imaging like CT/MRI/PET-CT for suspected ovarian cancer [8]. CA125 is NOT useful in the acute setting of torsion. It is elevated in ovarian malignancy (especially epithelial), endometriosis, PID, and even normal menstruation. It is used for the Risk of Malignancy Index (RMI) in postmenopausal women with ovarian cysts [16], not for diagnosing torsion. |
| AFP, βhCG, LDH | Germ cell tumour markers. Relevant if the underlying cyst is suspected to be a malignant germ cell tumour (e.g., immature teratoma in young women). Not part of the initial torsion workup. |
| Inhibin, AMH | Sex cord-stromal tumour markers. Not routinely measured in acute torsion. |
4. Imaging — The Centrepiece
Pelvic ultrasound is a common investigation tool [8]. This is the first and most important imaging modality for suspected ovarian torsion.
Two approaches:
| Modality | Advantages | Limitations |
|---|---|---|
| Transvaginal ultrasound (TVS) | Higher resolution for pelvic structures; better visualisation of ovarian morphology; closer to the ovary | May be uncomfortable in acute pain; contraindicated in prepubertal patients; operator-dependent |
| Transabdominal ultrasound (TAS) | Non-invasive; better for large masses extending out of the pelvis; suitable for children/virgo intacta | Lower resolution for deep pelvic structures |
| Combined TVS + TAS | TVS + TAS [16] — optimal approach. TVS for detail, TAS for overview and large masses | Requires trained sonographer |
For the ovaries, look at the uterus first, at the sides. If you can find a cystic, follicular-filled structure, then that should be the ovaries. For some postmenopausal women, if the ovaries become atrophic, they are difficult to locate [17].
| Finding | Description | Pathophysiological Basis |
|---|---|---|
| Enlarged, oedematous ovary | Ovary appears significantly larger than contralateral (often > 4 cm in longest axis, compared to normal ~3 cm) with a rounded, globular shape | Venous congestion → oedematous swelling. Blood enters via arteries but cannot exit via compressed veins → ovary balloons up. |
| Underlying ovarian mass/cyst | Complex cystic lesion with heteroechogenic content [1] (as in dermoid); or simple cyst; or solid mass | The predisposing lesion that caused the torsion. USG: variable appearance depending on content [6] for teratomas. |
| Whirlpool sign | Twisted vascular pedicle seen as a round, hypoechoic structure with concentric rings on grey-scale, or a spiral of colour flow on Doppler | The physically twisted infundibulopelvic ligament/mesovarium. This is the most specific USS sign of torsion (specificity ~85–100%). Analogous to the whirlpool sign described in testicular torsion [14]. |
| Absent or reduced Doppler flow | No colour flow or reduced/absent arterial and venous waveforms within the ovary | Vascular occlusion from torsion. BUT — presence of flow does NOT exclude torsion because: (1) dual blood supply may preserve some flow; (2) partial torsion may not fully occlude vessels; (3) intermittent torsion-detorsion. Doppler USG cannot rule out [10]. |
| Peripheral follicles pushed to the cortex | Multiple small follicles displaced to the periphery of the swollen ovary, creating a "string of pearls" appearance at the edge | Oedema in the ovarian stroma pushes the cortical follicles outward. This sign is particularly useful in torsion of a normal ovary (no underlying mass). |
| Free fluid in Pouch of Douglas | Small to moderate amount of anechoic or echogenic fluid posterior to the uterus | Reactive peritoneal fluid from congested/ischaemic ovary. In the lecture case, no fluid at POD was noted [1] — demonstrating that free fluid is not always present. Its absence does not exclude torsion. |
| "Missing ovary" sign | Left ovary not seen on USS with an ipsilateral adnexal mass [1] | The torted, oedematous ovary is so distorted and enlarged that the sonographer cannot identify it as a normal ovary — instead, they see the cyst/mass. The ovary IS the mass. |
| Midline deviation of the ovary | The torted ovary may be displaced medially, anterior to or above the uterus | The twist on the pedicle can pull the ovary out of its normal lateral position. In the lecture case: complex cystic lesion at left antero-lateral aspect of uterus [1] and cystic mass felt in the anterior fornix [1]. |
Critical Exam Point – Doppler Flow and Torsion
The most common exam pitfall: Students (and clinicians) assume that normal Doppler flow excludes ovarian torsion. It does NOT. The sensitivity of absent Doppler flow for torsion is only ~50–75%. Up to 60% of confirmed torsion cases have some detectable flow on Doppler. Always correlate with clinical findings. If clinical suspicion is high, proceed to surgery regardless of Doppler results.
| Underlying Pathology | USS Appearance |
|---|---|
| Dermoid cyst | Heteroechogenic content [1]; mixed echogenicity with echogenic foci (fat, hair), calcification (teeth), "dermoid plug," "tip of the iceberg" sign (dense echogenic component obscures deeper structures). AXR: tooth-shaped radiodensity [6]. CT/MRI: definitive dx, esp when fat content is demonstrated [6]. |
| Simple/functional cyst | Anechoic, avascular [6] — thin-walled, no internal echoes, no solid components, no septations. |
| Endometrioma | "Ground glass" homogeneous low-level internal echoes (old blood); thick wall; no internal vascularity. |
| Cystadenoma | Thin-walled, unilocular or multilocular, may have thin septations. Serous = anechoic; mucinous = low-level echoes. |
| Malignant features | Heterogeneous with solid component; irregular wall; papillary projections; increased vascularity; multilocular [3]. If any of these are present, raise suspicion for malignancy → refer to gynaecological oncology MDT. |
Should also check for Doppler flow [3] — the lecture explicitly emphasises adding Doppler to all pelvic USS assessments.
Not a primary investigation for ovarian torsion, but can provide incidental clues:
- AXR: tooth-shaped radiodensity in LLQ [6] → diagnostic of dermoid cyst (the teeth/bone within the teratoma are radio-opaque).
- Impression: Ovarian teratoma with recurrent torsion/detorsion [6].
- AXR may also show calcifications within mature cystic teratomas.
- Limitation: AXR is insensitive for most ovarian pathology and is not recommended as a primary investigation. The dermoid cyst finding on AXR is usually incidental.
CT abdomen and pelvis: emergency, eg. GI obstruction or perforation, stones, peritonitis [18].
| Role in Torsion | Details |
|---|---|
| Not first-line | USS is preferred because it is faster, radiation-free, cheaper, and provides real-time Doppler assessment. CT is used when USS is equivocal or when an alternative diagnosis (appendicitis, diverticulitis) needs to be excluded. |
| CT findings of torsion | Enlarged, oedematous ovary; thickened, twisted pedicle ("whirl sign"); wall thickening of the fallopian tube; deviation of the uterus to the affected side; pelvic free fluid; reduced or absent enhancement of the ovary on contrast CT (indicates ischaemia). |
| CT for dermoid | CT/MRI: definitive dx, esp when fat content is demonstrated [6]. CT shows macroscopic fat within the cyst (fat = very low attenuation, typically -20 to -120 HU), calcification (teeth, bone), and the Rokitansky nodule. |
| Contrast CT | IV contrast helps assess ovarian perfusion — a non-enhancing ovary on contrast CT strongly suggests ischaemia/infarction. |
| Radiation exposure | Significant concern in young reproductive-age women (ovarian radiation dose). Avoid if USS is diagnostic. |
- Role: Second-line imaging; used when USS is inconclusive and CT is to be avoided (e.g., pregnancy, young patients, radiation concerns).
- CT/MRI: definitive dx, esp when fat content is demonstrated [6] — MRI is excellent for tissue characterisation.
- MRI findings in torsion: Enlarged ovary with stromal oedema (high T2 signal); twisted pedicle; haemorrhagic changes; non-enhancement of ovary post-gadolinium.
- MRI advantage in pregnancy: No ionising radiation; safe for the fetus (gadolinium generally avoided in pregnancy, but non-contrast MRI is useful).
- Limitation: Takes longer (~30–45 minutes); less readily available in emergencies.
Diagnostic laparoscopy [13] — the gold standard and definitive investigation for ovarian torsion.
- This is both diagnostic AND therapeutic — you can visualise the torsion and immediately perform detorsion/cystectomy/oophorectomy in the same procedure.
- Intraoperative finding: a 7 cm left ovarian cyst with torsion for 1.5 turn. Satisfactory perfusion of left ovary noted after detorsion [1].
- Torsion of the stalk / infundibulopelvic ligament [15] — directly seen at laparoscopy.
What you see at laparoscopy:
| Finding | Significance |
|---|---|
| Twisted pedicle (infundibulopelvic ligament / mesovarium) | Confirms the diagnosis; count the number of turns |
| Colour of ovary — dusky blue/black vs pink | Indicates degree of ischaemia; satisfactory perfusion noted after detorsion [1] = ovary recovers pink colour = viable |
| Oedematous, enlarged ovary | Consistent with venous congestion |
| Sebum and hair found inside the cyst [1] | Confirms dermoid cyst as underlying pathology |
| Normal contralateral ovary and uterus | Uterus and right ovary normal [1] |
- All excised ovarian tissue should be sent for histological examination to confirm the underlying pathology and exclude malignancy.
- Pathology: Mature cystic teratoma of left ovary [1] — this was the definitive histological diagnosis in the lecture case.
- Immature teratoma (malignant) accounts for ~5% of ovarian teratomas [19] — histology distinguishes mature (benign) from immature (malignant) based on the presence of immature neural tissue.
| Priority | Investigation | Purpose | Key Findings |
|---|---|---|---|
| 1 | βhCG (urine/serum) | Exclude pregnancy | Negative in pure torsion |
| 2 | Urinalysis | Exclude urological cause | Normal |
| 3 | CBC, CRP | Assess inflammation/necrosis, pre-op | Mild leukocytosis; elevated CRP if necrotic |
| 4 | Group and save, coagulation, RFT | Pre-operative preparation | Baseline values |
| 5 | Pelvic USS (TVS + TAS with Doppler) | Primary imaging | Enlarged ovary, whirlpool sign, reduced flow, underlying mass |
| 6 | CT abdomen/pelvis | If USS equivocal or alternative Dx suspected | Whirl sign, non-enhancing ovary, fat in dermoid |
| 7 | MRI pelvis | If USS equivocal + CT to be avoided | Stromal oedema, twisted pedicle, tissue characterisation |
| 8 | Diagnostic laparoscopy | Definitive — diagnostic AND therapeutic | Twisted pedicle visualised; ovarian viability assessed |
| 9 | Histopathology | Post-operative | Confirms underlying pathology; excludes malignancy |
The Risk of Malignancy Index (RMI) [16] is used for postmenopausal women with ovarian cysts to determine the likelihood of malignancy and guide referral. While not specific to torsion, it is relevant because the underlying cyst in a torted ovary may need malignancy risk stratification, especially in older women.
RMI I = Menopausal status score × USS score × CA125 level [16]
| Component | Scoring |
|---|---|
| Menopausal status (M) | Pre-menopausal = 1; Post-menopausal = 3 |
| USS score (U) | 0 features = 0; 1 feature = 1; ≥ 2 features = 3. Features: multilocular, solid areas, bilateral, ascites, metastases |
| CA125 | Absolute value in U/mL |
- RMI < 200: low risk of malignancy → consider conservative management if meets all criteria (asymptomatic, simple, < 5 cm, unilocular, unilateral) [16].
- RMI ≥ 200: increased risk of malignancy → CT scan (abdomen and pelvis), referral for gynaecological oncology MDT review [16].
When Does RMI Apply in Torsion?
If a postmenopausal woman presents with ovarian torsion, the underlying cyst should be assessed for malignancy risk using RMI postoperatively. However, in the acute emergency setting, the priority is detorsion to save the ovary (or oophorectomy if non-viable). Malignancy workup follows after the emergency is resolved.
PV detect Left adnexal mass. The patient has urinary incontinence, which investigation is most appropriate? Answer: E. Transvaginal US [20].
This past exam question reinforces that transvaginal ultrasound is the investigation of choice for evaluating an adnexal mass. The rationale: TVS provides superior resolution for pelvic structures compared to TAS, CT, or MRI, and is non-invasive with no radiation.
High Yield Summary – Diagnosis and Investigations
- Ovarian torsion is a surgical diagnosis — definitive confirmation is intraoperative visualisation of the twisted pedicle at laparoscopy.
- No formal diagnostic criteria or scoring system exists — diagnosis is based on a constellation of clinical features + USS findings + surgical confirmation.
- βhCG is always the first investigation — to exclude ectopic pregnancy and other pregnancy-related causes.
- Pelvic ultrasound (TVS + TAS with Doppler) is the primary imaging modality.
- Key USS signs of torsion: Enlarged oedematous ovary, whirlpool sign (most specific), reduced/absent Doppler flow, peripheral follicles, underlying cyst/mass, free fluid, "missing ovary" sign.
- Doppler flow does NOT exclude torsion — sensitivity of absent flow is only ~50–75% due to dual blood supply and partial torsion.
- CT is second-line (radiation concern in young women); MRI is useful in pregnancy or when CT is contraindicated.
- If clinical suspicion is high, proceed to surgery regardless of imaging findings — do not delay for "definitive" imaging.
- All excised tissue → histopathology to confirm underlying pathology and exclude malignancy.
- RMI score is used for postmenopausal ovarian cysts to stratify malignancy risk — not specific to torsion but relevant for the underlying cyst.
Active Recall - Diagnosis and Investigations for Ovarian Torsion
References
[1] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf (Cards 13–19) [3] Lecture slides: Block C - O&G Theme Case 3.pdf (p4) [5] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p12, p20) [6] Senior notes: Ryan Ho Radiology.pdf (p33) [8] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p26, p71) [10] Senior notes: Maksim Surgery Notes.pdf (p328, p336) [12] Senior notes: Ryan Ho Fundamentals.pdf (p279) [13] Senior notes: Ryan Ho GI.pdf (p105) [14] Senior notes: Ryan Ho Urogenital.pdf (p231–233) [15] Lecture slides: Block C - Pelvic mass_ ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p41) [16] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p68) [17] Lecture slides: Block C - Pelvic mass_ ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p30) [18] Senior notes: Ryan Ho Diagnostic Radiology.pdf (p36) [19] Senior notes: Ryan Ho Rheumatology.pdf (p167) [20] Senior notes: Ryan Ho Radiology.pdf (p40)
Management of Ovarian Torsion
Before diving into specifics, let's establish the management philosophy from first principles:
- Time is gonad — ovarian torsion is a surgical emergency. The longer the delay to detorsion, the greater the ischaemic damage and the lower the chance of ovarian salvage. Current evidence suggests the ovary can tolerate ischaemia for longer than the testis (hours to even days in some cases), but earlier intervention = better outcomes.
- Conservative surgery (ovarian-sparing) is preferred — the modern approach favours detorsion ± cystectomy with ovarian conservation over oophorectomy, especially in reproductive-age women and children. Even a dusky/blue-black ovary at surgery may recover function after detorsion.
- The previously held fear that untwisting a necrotic ovary causes thromboembolism is now considered unfounded — multiple large studies have shown no increased risk of PE/DVT after detorsion of even necrotic-appearing ovaries. This historical concern led to unnecessary oophorectomies for decades.
- Shock, severe pain (peritoneal signs) — may require straight laparotomy [7] — haemodynamic instability mandates immediate resuscitation and surgical intervention, potentially via laparotomy rather than laparoscopy.
Phase 1: Initial Resuscitation and Stabilisation
This follows the standard surgical acute abdomen protocol: Diet – NPO, IV fluid; Activity – bed rest; Vitals – resuscitate early; Ix – as indicated; Drugs – as indicated [21].
- Assess haemodynamic stability: BP, pulse, capillary refill, peripheral perfusion.
- If signs of hypovolaemic shock [4] (from rare haemorrhagic rupture of torted ovary) → resuscitate immediately:
- High flow O₂ with BVM with reservoir [22].
- Obtain large bore IV access (14/16G at antecubital vein) [22].
- Take blood for CBC, RFT, clotting, T/S [22].
- Give rapid fluid challenge: 500 mL or 1000 mL crystalloid solution (balanced or NS) over 5–10 min [22].
- Reassess BP/P every 5 min → repeat fluid challenge if not responding [22].
- Consider Foley's catheter for UO monitoring (target > 0.5 mL/kg/h) [21].
- Why? The patient will likely need general anaesthesia for surgery. Eating/drinking increases aspiration risk during intubation. Standard pre-operative fasting: 6 hours for solids, 2 hours for clear fluids.
- NPO; IV fluid: routinely 2D1S Q8h [21] — maintenance fluids while fasting.
- Why is adequate analgesia critical? Severe visceral pain triggers vagal responses (nausea, vomiting, bradycardia) and sympathetic activation (tachycardia, hypertension). Uncontrolled pain also impairs clinical assessment.
- Options:
- Paracetamol (1 g IV) — first-line, safe, minimal side effects.
- NSAIDs (e.g., ketorolac 30 mg IV or diclofenac 75 mg IM) — effective for visceral/inflammatory pain via prostaglandin synthesis inhibition. Avoid if concern for haemorrhage (antiplatelet effect) or renal impairment.
- Opioids (e.g., morphine 2–5 mg IV titrated, or fentanyl) — for severe pain unresponsive to non-opioids. Use with caution (respiratory depression, ileus).
- Anti-emetics (e.g., ondansetron 4 mg IV) — for nausea/vomiting, which is common due to autonomic stimulation from visceral pain.
Historical myth debunked: The old teaching that you should not give analgesia before surgical assessment (to avoid "masking signs") is now considered outdated and unethical. Adequate analgesia actually improves clinical assessment by allowing proper examination of a patient who is not writhing in agony.
- Prophylactic IV antibiotics — standard pre-operative surgical prophylaxis (e.g., IV cefazolin 2 g within 60 minutes of skin incision).
- If there is suspicion of established necrosis/infection (high fever, markedly elevated WBC, peritonitis), broader spectrum coverage is warranted (e.g., IV ceftriaxone + IV metronidazole for anaerobic coverage).
| Investigation | Purpose |
|---|---|
| CBC | Baseline Hb (for potential haemorrhage), WBC (necrosis/infection) |
| Coagulation profile | Pre-operative safety |
| Group and Save / Crossmatch | In case of intraoperative haemorrhage |
| RFT | Baseline renal function; hydration status |
| βhCG | Exclude pregnancy — affects surgical planning and anaesthetic management |
| Pelvic USS (if not already done) | Confirm adnexal mass; assess Doppler flow; look for free fluid |
| ECG | Pre-anaesthetic assessment (especially if > 40 years) |
| Chest X-ray | Pre-anaesthetic (if indicated by age/comorbidities) |
Phase 2: Definitive Surgical Management
Ovarian cyst complications, pregnancy complications require emergency management [23]. The definitive treatment of ovarian torsion is surgical.
| Approach | Indications | Advantages | Disadvantages |
|---|---|---|---|
| Laparoscopy [1] | First-line approach for all haemodynamically stable patients | Minimally invasive; shorter hospital stay; less post-operative pain; faster recovery; better cosmesis; excellent pelvic visualisation | Requires trained surgeon; may be challenging if massive ovarian enlargement or dense adhesions; pneumoperitoneum contraindicated in some situations |
| Straight laparotomy [7] | Shock, severe pain (peritoneal signs) [7]; massive ovarian mass; suspected malignancy requiring staging; laparoscopy not technically feasible | Better access for large masses; full staging if malignancy suspected; can handle massive haemorrhage | Larger incision; more post-operative pain; longer recovery; higher wound complication rate |
Laparoscopy [1] is the modern gold standard. The lecture glossary explicitly lists Laparoscopy 腹腔鏡 [1] as a key procedure in gynaecological emergencies. In current practice (2025–2026), the vast majority of ovarian torsion cases are managed laparoscopically.
Step 1: Entry and Inspection
- Standard laparoscopic entry (Veress needle or Hassan open technique at the umbilicus).
- Inspect the pelvis: identify the torted ovary, assess the degree of torsion (number of turns), assess the contralateral ovary, uterus, tubes, and appendix.
- Intraoperative finding: A 7 cm left ovarian cyst with torsion for 1.5 turn. Uterus and right ovary normal [1].
- Ovarian cyst → appreciate there is torsion of the stalk / infundibulopelvic ligament [15].
Step 2: Detorsion
- Untwist the ovary by grasping it gently with atraumatic forceps and rotating it back to its anatomical position.
- This is the critical manoeuvre — restoring the vascular pedicle to its normal orientation allows blood flow to resume.
- The principle is identical to testicular torsion: detorsion → assess viability [10].
Step 3: Assess Ovarian Viability
- After detorsion, wait 10–15 minutes and observe for signs of reperfusion:
| Sign | Interpretation |
|---|---|
| Colour change from dusky blue/black to pink/red | Viable — blood flow is restored; the ovary is reperfusing |
| Bleeding from ovarian surface when incised | Viable — active circulation confirmed |
| Satisfactory perfusion of left ovary noted after detorsion [1] | Viable — proceed to ovarian conservation |
| Remains black/necrotic, no colour change, no bleeding | Non-viable — oophorectomy required |
| Intraoperative Doppler (if available) | Can assess for return of flow, though visual assessment is usually sufficient |
This is analogous to testicular torsion assessment: wrap in warm gauze – observe if it gets redder, incise on tunica albuginea for fresh bleeding [10]. The same principle applies to the ovary.
Modern Practice – Detorsion Even of Black Ovaries
Current evidence strongly supports detorsion even when the ovary appears black/necrotic. Studies show that >90% of ovaries that appear non-viable at surgery actually recover function within weeks to months. The dark colour is due to venous congestion and haemorrhagic infarction of the cortex, but the deeper ovarian tissue (medulla, follicles) may still be viable. Therefore, do NOT perform oophorectomy based solely on ovarian colour — always attempt detorsion first and reassess. The only exceptions are clear signs of irreversible necrosis (frank pus, tissue fragmentation) or suspected malignancy.
Step 4: Address the Underlying Pathology
| Scenario | Surgical Procedure | Rationale |
|---|---|---|
| Viable ovary + benign-appearing cyst | Cystectomy [1] — excise the cyst while preserving the remaining ovarian tissue | Removes the cause of torsion (the mass that made the ovary heavy/unstable) while conserving ovarian function (fertility, hormones). Cystectomy performed [1] in the lecture case. |
| Viable ovary + no cyst (normal ovary torsion) | Detorsion alone ± oophoropexy (fixing the ovary to the pelvic sidewall or uterosacral ligament with sutures) | Prevents recurrence by anchoring the ovary so it cannot twist again. Most relevant in children/adolescents with normal ovary torsion. |
| Viable ovary + cyst suspicious for malignancy | Oophorectomy ± full staging (omentectomy, peritoneal biopsies, peritoneal washings) | If there are features concerning for malignancy (solid components, papillary projections, irregular wall, ascites), the ovary should NOT be opened (risk of tumour spillage). Refer to gynaecological oncology. |
| Non-viable ovary | Oophorectomy ± salpingectomy (if the tube is also necrotic) | Non-viable tissue must be removed to prevent infection, abscess, and sepsis. |
| Post-menopausal woman | Oophorectomy (± bilateral salpingo-oophorectomy) | No fertility preservation needed; removes risk of recurrence and potential underlying malignancy. |
Step 5: Specimen Handling
- Sebum and hair found inside the cyst [1] — all excised tissue (cyst contents, ovarian tissue) is sent for histopathological examination.
- Pathology: Mature cystic teratoma of left ovary [1] — histology confirms the final diagnosis and excludes malignancy (e.g., immature teratoma).
Step 6: Inspect the Contralateral Ovary
- Assess the contralateral ovary for any cysts or masses that might predispose to future torsion.
- Unlike testicular torsion (where bilateral orchidopexy is standard), routine contralateral oophoropexy is not standard practice unless there is a bilateral predisposing condition (e.g., bilateral dermoid cysts).
2c. Special Situations
| Consideration | Detail |
|---|---|
| Timing | Most common in first trimester (corpus luteum cyst) and after ovarian hyperstimulation |
| Surgical approach | Laparoscopy is safe in pregnancy (especially 1st and early 2nd trimester). After ~16 weeks, open surgery or modified port placement may be needed as the uterus enlarges. |
| Anaesthetic concerns | Left lateral tilt to avoid aortocaval compression (after 20 weeks); aspiration prophylaxis (progesterone relaxes the lower oesophageal sphincter). |
| CO₂ pneumoperitoneum | Use low insufflation pressures (10–12 mmHg) to minimise effects on fetal perfusion and maternal venous return. |
| Corpus luteum preservation | Before 10–12 weeks, the corpus luteum is essential for progesterone production to maintain the pregnancy. If oophorectomy is required before 10–12 weeks, exogenous progesterone supplementation is mandatory to prevent miscarriage. After 12 weeks, the placenta takes over progesterone production (luteo-placental shift). |
| Fetal monitoring | Intraoperative fetal heart rate monitoring if viable gestational age (generally > 24 weeks). |
| Consideration | Detail |
|---|---|
| Normal ovary torsion | More common in this age group (elongated ligaments, no adhesions). |
| Conservative approach | Detorsion ± oophoropexy. Ovarian conservation is paramount to preserve future fertility and endocrine function. |
| Examination | Do not PV on your own (consult Gynae!!) [10] — vaginal examination is inappropriate in prepubertal children; use TAS (not TVS). |
| Avoid unnecessary oophorectomy | Even necrotic-appearing ovaries in children should undergo detorsion first; recovery rates are high. |
- Management complicated, depends on many factors. If operable, want to operate first → time-sensitive operation, therapeutic and diagnostic [24].
- If malignancy is suspected (USS features: solid components, papillary projections, ascites, elevated CA125), do NOT perform cystectomy (risk of rupturing a malignant cyst → tumour spillage → upstaging).
- Instead: intact oophorectomy via an endobag (to prevent spillage) → frozen section intraoperatively → if malignant, proceed to full staging (laparotomy, full staging procedure by a trained gynaecological oncologist [16]).
- TAH + BSO + omentectomy + peritoneal cytology [16] — the standard staging procedure for confirmed ovarian malignancy (not performed for benign torsion).
| Aspect | Details |
|---|---|
| Analgesia | Regular paracetamol ± NSAIDs; opioids as rescue. Multimodal analgesia reduces opioid requirements. |
| Diet | Clear fluids once awake; advance to normal diet as tolerated (usually within 24 hours for laparoscopy). |
| Mobilisation | Early mobilisation (day of surgery for laparoscopy) — reduces VTE risk, ileus, and respiratory complications. |
| VTE prophylaxis | Mechanical (TED stockings, pneumatic compression devices) ± pharmacological (LMWH e.g., enoxaparin 40 mg SC daily) based on risk assessment. |
| Antibiotics | Continue only if there was established necrosis/infection. Otherwise, a single pre-operative prophylactic dose is sufficient. |
| Histology results | Review pathology results within 1–2 weeks. If malignancy found unexpectedly (e.g., immature teratoma, borderline tumour), refer to gynaecological oncology for further management. |
| Follow-up | USS at 6–8 weeks to assess ovarian morphology and blood flow, confirm recovery of the conserved ovary, and ensure no recurrence. |
| Strategy | Details |
|---|---|
| Cystectomy of the predisposing lesion | Removing the cyst eliminates the mass effect that caused torsion. Most important preventive measure. |
| Oophoropexy | Suturing the ovary to the pelvic sidewall or uterosacral ligament. Considered in: (1) normal ovary torsion, (2) recurrent torsion, (3) remaining ovary in a patient who has lost the contralateral ovary. Evidence is limited but increasingly practiced. |
| Shortening the utero-ovarian ligament | Plication of the ligament reduces the "pendulum length" and limits ovarian mobility. Less commonly performed. |
| Surveillance of known ovarian cysts | Patients with known ovarian cysts that are managed conservatively (e.g., functional cysts expected to resolve) should be counselled about torsion symptoms and instructed to seek emergency care if sudden pain occurs. |
| Treatment | Indications | Contraindications / Cautions |
|---|---|---|
| Laparoscopic detorsion + cystectomy | First-line for all stable patients with benign-appearing cysts | Haemodynamic instability; suspected malignancy requiring full staging; very large masses not amenable to laparoscopic extraction; lack of laparoscopic expertise |
| Laparotomy | Haemodynamic instability; suspected malignancy; technically not feasible laparoscopically | None absolute — but higher morbidity than laparoscopy, so avoided if laparoscopy is feasible |
| Oophorectomy | Non-viable ovary after attempted detorsion; post-menopausal women; suspected malignancy | Should NOT be performed based solely on ovarian appearance (blue/black colour) without attempting detorsion first in reproductive-age women |
| Oophoropexy | Normal ovary torsion (especially children); recurrent torsion; solitary remaining ovary | Risk of chronic pain from fixation sutures; may distort tubo-ovarian anatomy and impair fertility (theoretical concern — not proven) |
| Conservative (non-operative) management | NOT an option for confirmed torsion | Torsion is a surgical condition; non-operative management risks permanent ovarian loss, necrosis, peritonitis, and sepsis |
What NOT to Do
- Do NOT delay surgery waiting for "better" imaging — if clinical suspicion is high, operate.
- Do NOT perform oophorectomy without attempting detorsion — even black-looking ovaries can recover.
- Do NOT open a cyst if malignancy is suspected — risk of tumour spillage and upstaging.
- Do NOT forget βhCG — torsion in early pregnancy requires special considerations (corpus luteum preservation, progesterone supplementation if oophorectomy performed before 12 weeks).
- Do NOT PV a child — use TAS; consult gynaecology.
Understanding the parallel helps consolidate learning:
| Aspect | Ovarian Torsion | Testicular Torsion |
|---|---|---|
| Surgical approach | Laparoscopy [1] (first-line) | Open scrotal exploration |
| Detorsion | Laparoscopic detorsion | Urgent scrotal exploration, detorsion [10] |
| Viability assessment | Observe colour change after detorsion; wait 10–15 min | Wrap in warm gauze, observe if it gets redder, incise on tunica albuginea for fresh bleeding [10] |
| Viable | Detorsion ± cystectomy ± oophoropexy | Bilateral orchidopexy [10] |
| Non-viable | Oophorectomy | Orchidectomy [10] |
| Contralateral fixation | Not routine (unless specific indication) | Bilateral orchidopexy is standard [10] |
| Manual detorsion | Not typically attempted (ovary not accessible externally) | Attempt manual detorsion if emergency OT not available [10] |
| Time window | Longer tolerance (hours to days — though earlier = better) | Viability decreases after 6h; irreversible damage after 12h [10][14] |
High Yield Summary – Management of Ovarian Torsion
- Ovarian torsion is a surgical emergency — the goal is urgent detorsion to salvage the ovary.
- Resuscitate first (ABC): NPO, IV access, analgesia, anti-emetics, IV fluids, bloods including βhCG and Group & Save.
- Laparoscopy is the gold standard surgical approach for stable patients.
- Straight laparotomy for haemodynamically unstable patients or suspected malignancy requiring staging.
- Detorsion → assess viability → address underlying pathology is the intraoperative sequence.
- Ovarian conservation is preferred — even black/necrotic-appearing ovaries should be detorted; > 90% recover function.
- Cystectomy preserving ovarian tissue for benign cysts; oophorectomy only if truly non-viable or suspicious for malignancy.
- In pregnancy: preserve corpus luteum before 12 weeks; if oophorectomy is necessary before 12 weeks, give exogenous progesterone.
- In children: ovarian conservation is paramount; do not perform PV examination.
- Suspected malignancy: do NOT open the cyst; intact oophorectomy → frozen section → full staging if malignant.
- Follow-up: histology review + USS at 6–8 weeks.
Active Recall - Management of Ovarian Torsion
References
[1] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf (Cards 13–19, Glossary) [4] Senior notes: Ryan Ho Fundamentals.pdf (p273) [7] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p24) [10] Senior notes: Maksim Surgery Notes.pdf (p328) [14] Senior notes: Ryan Ho Urogenital.pdf (p233) [15] Lecture slides: Block C - Pelvic mass_ ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p41) [16] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p68) [21] Senior notes: Ryan Ho Fundamentals.pdf (p280) [22] Senior notes: Ryan Ho Critical Care.pdf (p21) [23] Lecture slides: Block C - Pelvic mass_ ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p18) [24] Lecture slides: Block C - Pelvic mass_ ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p57)
Complications of Ovarian Torsion
Understanding the complications of ovarian torsion requires thinking about what happens along the timeline of ischaemia — from the moment the ovary twists to the long-term consequences. Complications arise from three main mechanisms: (1) the torsion itself (ischaemia and its sequelae), (2) the underlying pathology (the cyst/mass that predisposed to torsion), and (3) the surgical intervention (operative and post-operative complications).
A. Complications of the Torsion Itself (Pre-operative / Untreated)
- Mechanism: The fundamental complication. Prolonged vascular occlusion → venous congestion → arterial ischaemia → haemorrhagic infarction → irreversible necrosis. Once the ovarian tissue is truly necrotic, it cannot be salvaged and oophorectomy becomes necessary.
- Why it matters: Loss of an ovary means loss of 50% of the ovarian follicular reserve. In a woman with a single functioning ovary (e.g., previous contralateral oophorectomy), this means complete loss of ovarian function → premature ovarian insufficiency (see below).
- Time-dependence: Unlike the testis (viability decreases after 6h; irreversible damage after 12h [14]), the ovary appears to tolerate ischaemia somewhat longer — potentially because of its dual blood supply and lower metabolic rate. However, salvage rates decrease significantly with delays beyond 24–36 hours, and the exact window is unpredictable.
- Mechanism: ± S/S of intra-abdominal bleeding; ± S/S of hypovolemic shock [4][9]. The congested, ischaemic ovary can rupture, releasing blood into the peritoneal cavity. This is essentially a ruptured haemorrhagic infarct — the ovary is engorged with trapped blood (venous outflow obstructed but arterial inflow initially continues), and if the capsule gives way, significant bleeding occurs.
- Clinical features: Signs of haemodynamic collapse [9] — tachycardia, hypotension, pallor, sweating, cold extremities, postural hypotension. Generalised abdominal tenderness with guarding.
- Severity: Can range from minor reactive peritoneal fluid (No fluid at POD [1] in mild cases) to frank haemoperitoneum requiring urgent resuscitation and straight laparotomy [7].
- Analogy: Think of this as similar to rupture of an ectopic pregnancy — an ischaemic, blood-engorged pelvic structure ruptures → haemoperitoneum → hypovolaemic shock.
- Mechanism: Once the ovary becomes necrotic, the dead tissue acts as a nidus for bacterial colonisation (bacterial translocation from the gut or haematogenous seeding). The necrotic debris and inflammatory mediators spill into the peritoneal cavity → chemical and eventually bacterial peritonitis.
- Clinical features: High fever ( > 38.5°C), generalised abdominal rigidity, rebound tenderness, absent bowel sounds (paralytic ileus), sepsis (tachycardia, hypotension, altered mental status).
- Why delayed presentation is dangerous: Torsion: often a/w waves of nausea and vomiting ± fever/↑WBC (suggests necrosis) [11]. Fever and markedly elevated WBC in the context of torsion are red flags indicating that necrosis and peritonitis may be developing.
- Mechanism: Progression from local peritonitis → systemic inflammatory response syndrome (SIRS) → sepsis → septic shock → multi-organ dysfunction. Necrotic ovarian tissue releases damage-associated molecular patterns (DAMPs) and bacterial products (if superinfected) → cytokine storm → vasodilation, capillary leak, coagulopathy.
- Relevance: This is a late and life-threatening complication of delayed or missed ovarian torsion. The mortality risk increases dramatically once sepsis develops.
- Mechanism: If the necrotic ovary becomes walled off by omentum and adjacent bowel loops, a localised collection of pus can form — a pelvic abscess. This is the ovarian equivalent of an appendiceal abscess from complicated appendicitis (abscess, gangrene, perforation [10]).
- Clinical features: Persistent fever despite antibiotics, pelvic mass on examination, elevated WBC/CRP, fluid collection on imaging (USS or CT).
- Management: Drainage (percutaneous image-guided or surgical) + IV antibiotics.
- Mechanism: Ischaemia, necrosis, and inflammation damage the peritoneal serosa, triggering fibrin deposition → fibrous adhesions between the ovary, tube, bowel, and pelvic sidewall. Adhesions form as part of the healing response, but they cause long-term problems.
- Consequences:
- Chronic pelvic pain — adhesions tether organs and cause traction on nerve-rich peritoneum.
- Infertility — adhesions can distort tubo-ovarian anatomy, blocking the fimbriae from capturing the oocyte or obstructing the tubal lumen.
- Bowel obstruction — pelvic adhesions can entrap small bowel loops, causing adhesive small bowel obstruction (a delayed complication that can present weeks to years later).
- Less mobile if adhesions, endometriosis [5] — paradoxically, adhesions from a previous torsion episode may actually reduce the risk of recurrent torsion by limiting ovarian mobility.
- Mechanism: Stasis within the compressed ovarian vein (Virchow's triad: stasis + endothelial injury from torsion + hypercoagulability if systemic inflammation) → thrombosis of the ovarian vein.
- Clinical significance:
- Right ovarian vein → IVC: Thrombosis can propagate into the IVC, and theoretically embolise to the lungs (pulmonary embolism). However, this is extremely rare and the previously held fear that detorsion causes PE has been debunked by multiple large studies.
- Left ovarian vein → left renal vein: Thrombosis can cause left renal vein congestion.
- Current evidence: The risk of clinically significant thromboembolism after detorsion is negligible (< 0.2% in large case series). This should NOT deter surgeons from attempting detorsion.
B. Complications Related to the Underlying Pathology
The torsion doesn't occur in isolation — there is usually an underlying ovarian cyst/mass that predisposed to it. Complications of the underlying pathology can coexist with or be triggered by the torsion:
- Ovarian cyst acute complications have 3 classical forms, all will present with abdominal pain → torsion, haemorrhage, rupture [3][25].
- Rupture [3] — the torsion can cause the cyst wall to become friable (ischaemic) → rupture → spillage of cyst contents into the peritoneal cavity.
- Chemical peritonitis from dermoid cyst rupture: Especially painful if dermoid cyst rupture [11] — because the sebaceous contents (fat, keratin, hair) provoke an intense inflammatory response in the peritoneum. This is a chemical peritonitis that can mimic surgical sepsis.
- Infection [25] — necrotic cyst wall provides a substrate for bacterial growth → infected ovarian cyst / tubo-ovarian abscess.
- Rare as a primary event but more common in the setting of necrosis from torsion.
C. Reproductive and Endocrine Consequences
- Mechanism: Oophorectomy (if ovary non-viable) reduces the total ovarian follicular reserve by ~50%. Even if the ovary is salvaged, ischaemic damage may destroy a proportion of primordial follicles, reducing the functional ovarian reserve.
- In young women and children: This is a particularly devastating consequence — preserving the ovary is critical for future fertility, which is why modern management strongly favours ovarian conservation.
- Adhesion-related infertility: Even with a salvaged ovary, post-inflammatory adhesions can distort tubo-ovarian anatomy (blocking fimbrial capture of oocytes or causing tubal occlusion).
- Quantification: Follow-up studies show that ~90% of women who undergo ovarian-sparing surgery (detorsion + cystectomy) have evidence of ovarian function on follow-up (normal follicular development on USS, normal AMH levels). This further supports the conservative approach.
- Mechanism: If oophorectomy is performed AND the patient already has a compromised contralateral ovary (e.g., prior surgery, endometriosis, congenital absence), or in the rare event of bilateral torsion, loss of both ovaries results in complete cessation of ovarian function → premature menopause.
- Consequences: Loss of oestrogen → menopausal symptoms (hot flushes, vaginal dryness, mood changes), accelerated bone loss (osteoporosis), cardiovascular risk, complete loss of fertility.
- Management: Hormone replacement therapy (HRT) with oestrogen ± progesterone until the expected age of natural menopause (~50 years).
These are standard complications of laparoscopic or open pelvic surgery:
| Complication | Mechanism / Detail |
|---|---|
| Wound infection | Surgical site contamination, especially if necrotic tissue was present |
| Intra-abdominal bleeding | From ovarian pedicle, cystectomy bed, or trocar site |
| Bowel or bladder injury | Inadvertent injury during laparoscopic entry or adhesiolysis (especially if prior surgery or dense adhesions) |
| Venous thromboembolism | General surgical risk — pelvic surgery + immobilisation + inflammation. Mitigated by early mobilisation and pharmacological thromboprophylaxis. |
| Port-site hernia | Laparoscopic port sites (especially ≥ 10 mm) can become incisional hernias |
| Paralytic ileus | Post-operative bowel dysfunction from peritoneal manipulation and opioid analgesia. Usually self-limiting. |
| Anaesthetic complications | Aspiration, drug reactions, difficult airway — standard general anaesthetic risks |
13. Recurrent Torsion
- Incidence: ~10% recurrence rate after ovarian-sparing surgery if the underlying predisposing factor is not addressed.
- Risk factors for recurrence:
- Failure to remove the predisposing cyst (if cystectomy not performed at initial surgery).
- Inherent ligamentous laxity (especially in children/adolescents).
- Contralateral torsion (less common, but the other ovary may have similar predisposing anatomy).
- Ovarian teratoma with recurrent torsion/detorsion [6] — dermoid cysts are particularly prone to recurrence if not excised, because the eccentric weight distribution persists.
- Prevention: Cystectomy (removes the mass), oophoropexy (fixes the ovary in place).
| Category | Complication | Mechanism | Time Course |
|---|---|---|---|
| Ischaemic | Ovarian necrosis | Prolonged vascular occlusion → infarction | Hours to days |
| Ischaemic | Haemoperitoneum | Rupture of congested/infarcted ovary | Acute |
| Ischaemic | Peritonitis | Necrotic tissue → chemical/bacterial inflammation | Days |
| Ischaemic | Sepsis | Progression from peritonitis → systemic | Days |
| Ischaemic | Pelvic abscess | Walled-off necrotic collection | Days to weeks |
| Ischaemic | Ovarian vein thrombosis | Stasis + endothelial damage + inflammation | Hours to days |
| Underlying cyst | Cyst rupture | Ischaemic friability of cyst wall | Acute |
| Underlying cyst | Haemorrhage into cyst | Venous congestion → intracystic bleeding | Acute |
| Underlying cyst | Cyst infection | Necrotic substrate → bacterial colonisation | Days |
| Reproductive | Reduced fertility | Loss of follicular reserve ± adhesions | Long-term |
| Reproductive | Premature ovarian insufficiency | Bilateral ovarian loss | Permanent |
| Post-operative | Adhesion formation | Peritoneal injury → fibrin → fibrosis | Weeks to months |
| Post-operative | Surgical complications | Bleeding, infection, injury, VTE | Perioperative |
| Recurrence | Recurrent torsion | Persistent predisposing anatomy/cyst | Weeks to years |
High Yield Summary – Complications of Ovarian Torsion
- Ovarian necrosis is the cardinal complication — the entire reason torsion is an emergency. Delay = irreversible gonadal loss.
- Haemoperitoneum can occur if the congested ovary ruptures → haemodynamic instability → may require straight laparotomy [7].
- Peritonitis and sepsis develop from necrotic tissue → high fever and markedly elevated WBC are red flags for established necrosis.
- Three classical acute complications of an ovarian cyst (torsion, haemorrhage, rupture) can coexist — dermoid cyst rupture is particularly painful due to chemical peritonitis from sebaceous contents.
- Adhesion formation causes chronic pelvic pain, infertility, and risk of bowel obstruction — but paradoxically may reduce recurrent torsion risk.
- Reduced fertility occurs from loss of follicular reserve (oophorectomy) or adhesion-related tubo-ovarian distortion — ovarian conservation is crucial in young women.
- Premature ovarian insufficiency if bilateral ovarian function is lost → requires HRT.
- Ovarian vein thrombosis is rare; the historical fear of PE from detorsion is debunked.
- Recurrence rate ~10% if predisposing factor not addressed — prevented by cystectomy and oophoropexy.
- Infection of the necrotic cyst is an additional complication to remember alongside the three classical acute complications.
Active Recall - Complications of Ovarian Torsion
References
[1] Lecture slides: Block C - Gyanecological Emergency Notes to Students.pdf (Cards 13–19) [3] Lecture slides: Block C - O&G Theme Case 3.pdf (p4) [4] Senior notes: Ryan Ho Fundamentals.pdf (p273) [5] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p12, p20) [6] Senior notes: Ryan Ho Radiology.pdf (p33) [7] Lecture slides: GC 118. Pelvic mass ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p24) [9] Senior notes: Ryan Ho GI.pdf (p100) [10] Senior notes: Maksim Surgery Notes.pdf (p328, p336) [11] Senior notes: Ryan Ho GI.pdf (p151) [14] Senior notes: Ryan Ho Urogenital.pdf (p233) [23] Lecture slides: Block C - Pelvic mass_ ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p18) [25] Lecture slides: Block C - Pelvic mass_ ovarian cancer and cysts; uterine fibroid; pelvic imaging.pdf (p9)
High Yield Summary
Definition: Partial/complete rotation of ovary (± fallopian tube) on vascular pedicle → venous obstruction first → arterial compromise → ischaemic necrosis.
Emergency: Time is gonad — same principle as testicular torsion.
Epidemiology: ~3% of gynaecological emergencies; peak 20–40 years; ~60% right-sided (sigmoid limits left mobility); 10–20% in pregnancy (corpus luteum/OHSS).
Most common cause: Ovarian mass 5–10 cm — dermoid cyst #1 (sediment → keeps rolling). Benign tumours torse more than malignant (malignancy adhesions = "sticky").
Other risk factors: OHSS, long pedicle, pregnancy, sudden exercise, normal ovary in children (lax ligaments).
Pathophysiology: Veins compress before arteries → congestion → oedema → ischaemia → necrosis.
Dual blood supply: ovarian artery (infundibulopelvic ligament) + uterine branch (utero-ovarian ligament) → Doppler flow does NOT exclude torsion.
Classic presentation: sudden severe unilateral pelvic pain ± N/V; colicky if intermittent torsion-detorsion; tender adnexal mass.
High Yield Summary — Differential Diagnosis
Always start with β-hCG — positive does not exclude torsion (adds ectopic, corpus luteum complications).
Gynaecological (priority): ovarian torsion, ruptured/haemorrhagic cyst, PID/TOA, mittelschmerz, endometrioma rupture, pedunculated fibroid torsion.
Pregnancy-related (if β-hCG +ve): ruptured ectopic, miscarriage, corpus luteum torsion, red degeneration of fibroid.
GI: appendicitis (especially RLQ — may mimic right adnexal pain), diverticulitis, mesenteric adenitis.
Urological: ureteric colic, UTI/pyelonephritis (urinalysis).
Key distinction from ruptured cyst: torsion = Doppler absent/reduced flow, whirlpool sign, enlarged oedematous ovary; rupture = free fluid + cyst wall collapse, may have preserved flow.
Rule: Clinical suspicion overrides equivocal imaging — proceed to surgery.
High Yield Summary — Diagnosis
No validated scoring system — surgical diagnosis confirmed intraoperatively (twisted pedicle visualised).
Pre-op constellation: sudden unilateral pain + adnexal tenderness/mass + enlarged ovary on USS ± absent flow ± whirlpool sign.
Bedside: ABC, β-hCG, urinalysis, CBC/CRP, group & save.
USS (supportive, not definitive):
- Enlarged oedematous ovary
- Underlying cyst (often dermoid)
- Whirlpool sign (twisted pedicle)
- Absent/reduced ovarian Doppler flow
- Free fluid
Critical pearls:
- Normal Doppler ≠ exclude torsion
- Do not delay surgery waiting for perfect imaging
- Definitive diagnosis = laparoscopy/laparotomy
High Yield Summary — Management
Phase 1 — Resuscitate: NPO, IV access, analgesia (do not withhold opioids), anti-emetics, IV fluids, pre-op antibiotics.
Unstable/shock/peritonitis: straight laparotomy after resuscitation.
Stable: urgent laparoscopy (gold standard).
Intraoperative:
- Detorsion first — even dusky/black ovary often recovers (no increased PE risk from detorsion — old teaching debunked)
- Assess viability after untwisting
- Viable ovary → detorsion + cystectomy if benign mass (prevents recurrence) ± oophoropexy if normal ovary
- Non-viable/necrotic → salpingo-oophorectomy
- Suspicious mass → gynae-oncology
Post-op: follow-up USS 6–8 weeks; counsel on recurrence risk if ovary conserved.
Pregnancy: same urgency — detorsion preferred; avoid unnecessary oophorectomy.
High Yield Summary — Complications
Untreated torsion: ovarian infarction → necrosis → peritonitis → sepsis → loss of ovary/tube → reduced fertility.
Delayed surgery: ↓ ovarian salvage rate; longer ischaemia = worse outcome (though ovary tolerates ischaemia longer than testis).
Recurrence: ~5–10% if underlying mass not removed or long pedicle; cystectomy reduces risk.
Bilateral torsion: rare (< 1%) but catastrophic for fertility.
Post-detorsion hyperaemia: transient post-operative pain/swelling — distinguish from ongoing ischaemia.
Misdiagnosis complications: treating as appendicitis/PID delays detorsion; treating as "wait for USS" loses ovary.
Exam trap: intermittent pain + teeth on imaging = recurrent torsion/detorsion of dermoid — still needs surgery.
Ovarian Cyst
An ovarian cyst is a fluid-filled sac that develops on or within the ovary, most commonly arising from follicular development or corpus luteum formation, and is often benign and self-limiting.
Uterine Fibroid
Uterine fibroids are benign smooth muscle tumors (leiomyomas) of the myometrium that can cause abnormal uterine bleeding, pelvic pain, and reproductive dysfunction.