Abnormal Vaginal Discharge

Understanding the anatomy is essential to localising the source of discharge and understanding the pathophysiology:

1. Vulva: External genitalia (labia majora, labia minora, clitoris, vestibule). Bartholin's glands (greater vestibular glands) lie at the 5 and 7 o'clock positions of the vaginal introitus — they secrete mucus for lubrication. Infection → Bartholin's abscess/cyst.

2. Vagina: A fibromuscular tube (~7–10 cm) lined by non-keratinised stratified squamous epithelium. This epithelium is oestrogen-responsive:

   • Oestrogen → epithelial proliferation and glycogen deposition
   • Glycogen → metabolised by Lactobacillus spp. → lactic acid → acidic pH (3.8–4.5)
   • This acidic milieu inhibits the growth of pathogenic bacteria
   • The vagina has no glands — discharge is a transudate through the epithelium plus cervical mucus

3. Cervix: The "gateway" between the lower and upper genital tract.

   • Ectocervix: Stratified squamous epithelium
   • Endocervix: Columnar epithelium with mucus-secreting glands
   • Transformation zone (squamocolumnar junction, SCJ): Where metaplasia occurs; the most vulnerable site for N. gonorrhoeae, C. trachomatis, and HPV infection
   • Cervical mucus changes with the cycle: thin/clear at ovulation (oestrogen), thick/scanty in luteal phase (progesterone)

4. Upper genital tract: Uterus, fallopian tubes, ovaries. Ascending infection from the cervix → endometritis → salpingitis → tubo-ovarian abscess → peritonitis/perihepatitis (Fitz-Hugh-Curtis syndrome).

• Dominated by Lactobacillus species (L. crispatus, L. jensenii, L. gasseri, L. iners)
• Produce lactic acid (maintains pH < 4.5), hydrogen peroxide (H₂O₂), and bacteriocins (antimicrobial peptides)
• Act as a biological barrier by competitive exclusion of pathogens
• Disruption of this flora (by antibiotics, douching, hormonal changes) is the fundamental mechanism underlying BV and susceptibility to STIs

Pelvic Inflammatory Disease (PID)

• Ascending infection from the cervix → endometrium → fallopian tubes → peritoneum
• Usually polymicrobial: N. gonorrhoeae, C. trachomatis, M. genitalium, anaerobes, enteric Gram-negatives
• Presents with: abnormal vaginal discharge, lower abdominal pain, fever, dyspareunia, abnormal uterine bleeding
• Physical examination: lower abdominal tenderness, cervical motion tenderness ("chandelier sign"), adnexal tenderness
• Fitz-Hugh-Curtis syndrome: perihepatitis — violin-string adhesions between liver capsule and anterior abdominal wall — sharp RUQ pain ^[6][7]

History taking for vaginal discharge should include ^[1][2][9]:

• Timing of discharge ^[1]
• Smell ^[1]
• Associated symptoms, e.g. abdominal pain, fever, pruritus ^[1]
• Contraception ^[1]
• Past health ^[1]
• Previous obstetrics history ^[1]
• Cervical smear ^[1]

Details of discharge: onset, duration, cyclicity, odor, color, consistency, exacerbating factors ^[4]

Sexual history (5 Ps) ^[3][9]:

• Present illness
• Practice (sexual orientation and practice, condom use)
• Past history of STDs and treatment
• Partners (for contact tracing, notify partner)
• Pregnancy ^[3]

"These are questions I ask for all patients in similar situation, and I ask only because it is important for me to know how to best manage your situation." — Use this phrasing to normalise sensitive sexual history questions ^[3].

Symptom-by-Symptom Breakdown with Pathophysiological Basis

Key timing clues ^[4]:

• Premenstrual → Candida (progesterone-dominant phase ↑ glycogen)
• Peri- or post-menstrual → Trichomonas, BV (alkaline menstrual blood ↑ pH)
• Post-coital → STDs (direct contact transmission; also cervicitis → PCB)

• pH < 4.5: Normal, or candidiasis (Candida thrives in acid conditions)
• pH > 4.5: BV, trichomoniasis, atrophic vaginitis, cervicitis (loss of Lactobacillus → loss of lactic acid)
• Why this matters: A simple pH test with litmus paper can immediately narrow the differential — if the pH is normal, BV and trichomoniasis are unlikely.

• Infectious: Candida, Trichomoniasis
• Benign: Dermatitis (contact, atopic)
• Rarely malignant: Vulvar cancer, vaginal cancer — especially in elderly with persistent, treatment-resistant pruritus

• Pregnancy alters vaginal flora and increases susceptibility to:
  • Candidiasis (↑ oestrogen → ↑ glycogen → Candida overgrowth)
  • BV (BV in pregnancy is associated with preterm labour, premature rupture of membranes, and low birth weight)
  • Group B Streptococcus (GBS) colonisation — not primarily a "discharge" issue but critical to screen in late pregnancy for neonatal sepsis prevention

• Poorly controlled DM → glycosuria and ↑ vaginal glucose → favours Candida overgrowth
• Pruritus vulvae may be a presenting feature of undiagnosed diabetes mellitus ^[5]
• Recurrent vulvovaginal candidiasis in a young woman → check fasting glucose/HbA1c

• Why it's top of the list: Single most common cause (~40–50%) of abnormal vaginal discharge in reproductive-age women ^[3]
• Key differentiating features:
  • Thin, homogeneous, greyish-white discharge that coats the vaginal walls
  • Fishy odour — worse post-coitally and during menses (amines volatilised by alkaline semen/menstrual blood)
  • Minimal pruritus and minimal inflammation — "vaginosis" not "vaginitis"
  • Normal vulva on examination ^[4] — because there is no significant inflammatory response
  • Vaginal pH > 4.5
• Why minimal inflammation? BV represents a dysbiosis (shift in microbial ecology) rather than an invasion/infection. The anaerobic bacteria form biofilms on the epithelium but do not invade tissue or elicit a strong PMN response. Hence "vaginosis" (condition of the vagina) not "vaginitis" (inflammation of the vagina).
• BV is NOT an STD ^[3], although it is associated with sexual activity

• Key differentiating features:
  • Thick, white, "cottage cheese-like" discharge ^[4]
  • Prominent vulvovaginal pruritus — the defining symptom
  • Erythema, oedema, fissures of the vulva
  • Vaginal pH normal ( < 4.5) — Candida thrives in acidic conditions, and the Lactobacillus flora may be intact
  • Timing: often premenstrual ^[4]
• Predisposing factors: pregnancy, diabetes, immunosuppression, oral contraceptive pills, broad spectrum antibiotics ^[10][11]
• Candidiasis is NOT an STD ^[3]
• Why does pH remain normal? Unlike BV and trichomoniasis, candidiasis does not displace Lactobacillus. The yeasts grow alongside them — they exploit excess glycogen but do not alter the acid-producing flora. So pH stays acidic. This is a critical bedside differentiator.

GC High Yield ^[10]: Predisposing factors for Candida are all related to an immunosuppressed state. A classical clinical picture is a patient who complains of cheesy discharge after finishing a course of broad spectrum antibiotics. Clinical features are sufficient to obtain a clinical diagnosis. Culture is obtained from the vaginal fornix and is more important in complicated infection (severe symptoms, pregnancy, recurrent, non-albicans Candida, abnormal host).

• Key differentiating features:
  • Greenish-yellow, frothy, purulent discharge ^[4]
  • Offensive odour
  • Pruritus present but typically less prominent than candidiasis
  • "Strawberry cervix" (colpitis macularis) — punctate haemorrhages on the cervix
  • Vaginal pH > 4.5
  • Timing: peri- or post-menstrual ^[4] — alkaline menstrual blood raises pH, favouring T. vaginalis
• Why frothy? T. vaginalis is a flagellated protozoan that produces CO₂ as a metabolic byproduct → gas bubbles trapped in the inflammatory exudate → frothy appearance
• This IS an STD — partner notification and treatment are essential

• Who: Post-menopausal women, post-oophorectomy, lactating, on anti-oestrogen therapy
• Key features: Thin, watery, sometimes blood-stained discharge; vaginal dryness; dyspareunia; pale/thin/friable mucosa with petechiae
• Why it happens: ↓ Oestrogen → atrophic epithelium → ↓ glycogen → loss of Lactobacillus → ↑ pH → susceptibility to enteric organisms and non-specific inflammation
• Critical point: In any post-menopausal woman with new vaginal discharge (especially blood-stained), you must exclude endometrial and cervical malignancy before attributing it to atrophic vaginitis

• Retained tampon, condom, pessary, or (in children) small objects
• Extremely foul-smelling, often bloody discharge
• Always consider foreign body in children and adolescents presenting with vaginal discharge ^[4]
• Diagnosis is made on speculum examination — foreign body visible in vagina ^[4]
• Why the smell? Retained material → local tissue necrosis → anaerobic bacterial overgrowth → volatile amines and sulphur compounds

• Contact dermatitis from soaps, perfumed products, latex condoms, spermicides, vaginal douches
• Pruritus predominant with erythema; discharge is usually watery/clear
• History of exposure to new products is the key clue

• A rare but important entity — chronic, purulent vaginal discharge with diffuse vaginal erythema and epithelial exfoliation
• Not infectious; thought to be inflammatory/autoimmune
• Responds to topical clindamycin or hydrocortisone
• Consider when standard infectious workup is negative and symptoms persist

• Incubation 2–7 days ^[6]
• Copious, purulent discharge ^[6]
• Mucopurulent endocervical discharge and friable cervical mucosa (easily induced endocervical bleeding) ^[6]
• Presence of abdominal pain and dyspareunia should raise suspicion for upper genital tract disease ^[6]
• Can cause Bartholinitis — perilabial pain, labial oedema, enlargement and tenderness of gland ^[6]
• Why copious? N. gonorrhoeae is a potent inducer of PMN chemotaxis (lipooligosaccharide, peptidoglycan fragments). The intense neutrophilic response produces the abundant purulent exudate.

• Most common bacterial cause of sexually transmitted infections ^[7]
• Incubation 5–10 days ^[7]
• Scanty, watery or mucoid discharge ^[7] — in contrast to gonorrhoea
• Often asymptomatic (70–80% of infected women) — this is why screening programmes exist
• Mucopurulent endocervical discharge and friable cervical mucosa ^[7]
• PID due to C. trachomatis is associated with higher rates of tubal infertility, ectopic pregnancy and chronic pelvic pain compared with N. gonorrhoeae ^[7]
• Why less purulent? C. trachomatis is an obligate intracellular pathogen — replicates inside inclusion bodies within the host cell. The inflammatory stimulus is less intense than gonorrhoea's extracellular PMN-attracting mechanisms, hence less purulent discharge.

Differential diagnosis for both gonorrhoea and chlamydia should include: Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, Mycoplasma genitalium, Treponema pallidum, Herpes simplex virus (HSV) ^[6][7]

STIs travel in packs — always consider multiple pathogens ^[3]. Co-infection with gonorrhoea and chlamydia is ~20–40%. Test for BOTH whenever one is suspected.

• Increasingly recognised as a cause of non-gonococcal cervicitis and urethritis
• Clinical features overlap with chlamydia (mucopurulent discharge, often mild)
• Cannot be detected by standard culture — requires NAAT
• Important because of rising macrolide resistance → treatment may require moxifloxacin

• Usually in the context of primary genital herpes (HSV-2 > HSV-1)
• Mucopurulent or watery cervical discharge
• Painful genital vesicles/ulcers, tender inguinal lymphadenopathy, dysuria
• Primary episode more severe than recurrences (systemic symptoms, wider lesion area)

• Not truly pathological — columnar epithelium extends onto the ectocervix (visible as a red ring around the os)
• Common in: OCP users, pregnancy, adolescents
• Produces mucoid discharge (columnar epithelium secretes mucus)
• May cause post-coital bleeding (fragile columnar tissue)
• Important to distinguish from cervicitis and cervical cancer on speculum examination

• Benign pedunculated growth from the endocervical canal
• Presents with mucoid discharge, intermenstrual bleeding, or post-coital bleeding
• Diagnosis: visible on speculum examination as a smooth, red/purple polypoid mass protruding from the cervical os

• Cervical smear history is important ^[1] — most cervical cancers arise in women with inadequate screening
• Presents with: blood-stained or watery discharge, post-coital bleeding, intermenstrual bleeding
• Advanced disease: foul-smelling discharge (tumour necrosis), pelvic pain, weight loss
• On speculum: irregular, friable, exophytic or ulcerative cervical mass
• This must be excluded in any woman with persistent unexplained vaginal discharge, especially post-menopausal

• Ascending infection from the cervix → endometrium → fallopian tubes → peritoneal cavity
• Usually polymicrobial: N. gonorrhoeae, C. trachomatis, M. genitalium, anaerobes, enteric Gram-negatives
• Key differentiating features: abnormal vaginal/cervical discharge + lower abdominal pain + fever + cervical excitation tenderness ("chandelier sign") + adnexal tenderness + deep dyspareunia ^[12]
• Fitz-Hugh-Curtis syndrome: perihepatitis presenting as sharp RUQ pain, fever — can be caused by both N. gonorrhoeae and C. trachomatis ^[6][7]

Differential diagnosis of PID ^[12]:

• Complication of PID: walled-off collection of pus involving tube and ovary
• Presents with: high fever, severe lower abdominal pain, adnexal mass palpable on bimanual examination
• Can rupture → peritonitis and septic shock (surgical emergency)

• Primarily a disease of post-menopausal women (though can occur in younger women with risk factors: obesity, PCOS, unopposed oestrogen, tamoxifen)
• Presents predominantly with post-menopausal bleeding but may also produce watery or blood-stained discharge
• Must be excluded in any post-menopausal woman with new vaginal discharge

• Ask about menstrual cycle timing, pregnancy status, OCP use
• If discharge is clear/white, non-offensive, no itch, no pain, and varies with cycle → likely physiological → reassurance

• Ask about tampon use, recent instrumentation
• Speculum examination is diagnostic

This is the core clinical distinction:

• Lower abdominal pain, fever, cervical motion tenderness, adnexal tenderness → think PID
• Always exclude ectopic pregnancy with a pregnancy test

• Persistent, unexplained discharge (especially blood-stained or watery) in a woman with:
  • No prior cervical screening
  • Post-menopausal status
  • Risk factors for endometrial cancer
• Requires speculum examination ± cervical smear/biopsy ± endometrial sampling

• Fistulae (IBD, post-surgical/obstetric)
• Urinary causes

Diagnosis requires 3 out of 4 criteria ^[14][15]:

Alternative diagnostic method — Nugent score (Gram stain scoring):

• A standardised microscopic grading system (0–10) based on the relative proportions of Lactobacillus morphotypes, Gardnerella/Bacteroides morphotypes, and curved Gram-variable rods (Mobiluncus)
• Score 0–3 = Normal; 4–6 = Intermediate; 7–10 = BV
• Considered the gold standard in research settings but less practical than Amsel criteria in routine clinical practice

• No single universally standardised "criteria" set like Amsel criteria for BV — diagnosis is a combination of clinical features and laboratory confirmation
• Clinical features are sufficient to obtain a clinical diagnosis ^[10][11]
• Diagnosis: clinical features + vaginal swab from vaginal fornix for microscopic examination ± culture ^[10]

Key diagnostic findings:

Culture is more important if the infection is complicated — defined as: severe symptoms, pregnancy, recurrent, non-albicans Candida, abnormal host ^[10][11]

Why culture in these situations?

• Severe/recurrent: Need to identify species — C. glabrata and C. krusei are intrinsically resistant to fluconazole and require different antifungal regimens
• Pregnancy: Need to confirm the diagnosis before treating (safety of antifungals differs in pregnancy)
• Abnormal host (immunocompromised): May harbour unusual species; antifungal susceptibility testing may be needed

Recommended diagnostic approach ^[6][16]:

NAAT is the optimal diagnostic method for both N. gonorrhoeae and C. trachomatis ^[6][7]. In practice, a single endocervical swab or first-void urine can be tested for both simultaneously using a combined GC/CT NAAT panel — this is now standard of care.

Recommended diagnostic approach ^[7]:

PID is a clinical diagnosis — there is no single definitive test. The threshold for diagnosis should be low because of the severe consequences of missed or delayed treatment (tubal infertility, ectopic pregnancy, chronic pelvic pain) ^[12]:

Minimum criteria (CDC 2021 / BASHH) — PID should be suspected and empirical treatment initiated in a sexually active young woman with:

• Uterine tenderness, OR
• Adnexal tenderness, OR
• Cervical motion tenderness
• In the absence of another identifiable cause

Additional criteria supporting the diagnosis ^[12]:

• Oral temperature > 38.3°C
• Abnormal cervical or vaginal mucopurulent discharge
• Abundant WBCs on saline microscopy of vaginal fluid
• Elevated ESR / CRP
• Laboratory evidence of cervical infection with N. gonorrhoeae or C. trachomatis

Specific (definitive) criteria:

• Endometrial biopsy with histopathological evidence of endometritis ^[12]
• Laparoscopic abnormalities consistent with PID ^[12]
• TVUS / MRI showing thickened, fluid-filled tubes (pyosalpinx) ± free pelvic fluid, tubo-ovarian complex ^[12]

Past paper point: For detection of a left adnexal mass on PV examination with urinary incontinence, the most appropriate investigation is transvaginal ultrasound ^[17]

AOS High Yield ^[18]: For investigation of abnormal vaginal bleeding/discharge, key further investigations include: pelvic ultrasound (assess endometrial thickness), endometrial aspiration (rule out carcinoma of uterine corpus and endometrial hyperplasia), cervical smear (opportunistic screening).

• Laparoscopic abnormalities consistent with PID ^[12] — considered the gold standard for PID diagnosis
• Findings: tubal erythema/oedema, purulent exudate from fimbrial ends, tubo-ovarian abscess
• Fitz-Hugh-Curtis syndrome: violin-string adhesions between liver capsule and anterior abdominal wall
• Not routinely performed for PID diagnosis (clinical diagnosis + low threshold to treat is the standard approach) — reserved for diagnostic uncertainty, failure to respond to treatment, or surgical complications (e.g., TOA drainage)

Treatment: metronidazole or tinidazole 2 g orally in a single dose (metronidazole 500 mg BD for 7 days may be required) ^[19]

Critical management points:

• This IS an STD → treat sexual partner simultaneously ^[19] — "ping-pong" reinfection occurs if partner is untreated
• Abstain from sex until both partners have completed treatment and are symptom-free
• Avoid alcohol during metronidazole/tinidazole treatment and for 48–72 hours after (disulfiram-like reaction — metronidazole inhibits aldehyde dehydrogenase → accumulation of acetaldehyde → flushing, nausea, vomiting, tachycardia)
• In pregnancy: Metronidazole 2 g single dose is acceptable from the 2nd trimester onward. BNF and WHO consider metronidazole safe in pregnancy (benefits outweigh theoretical risks). Tinidazole is less well studied in pregnancy and generally avoided.
• Metronidazole-resistant trichomoniasis: Rare but increasing. Use higher-dose metronidazole (2 g PO daily × 7 days) or tinidazole 2 g PO daily × 7 days. If persistent, consult infectious disease/sexual health specialist.

Management principles:

• Partner notification and treatment — sexual contacts in past 60 days
• Abstain from sex for 7 days after treatment (both patient and partner)
• Test of cure — NAAT at ≥ 3 weeks post-treatment (earlier NAAT may detect dead DNA → false positive). Recommended for pregnant women, persistent symptoms, or uncertain compliance
• Chlamydial PID is associated with higher rates of tubal infertility, ectopic pregnancy, and chronic pelvic pain ^[7] → early and complete treatment is critical

Special Situations

Pragmatic approach for M. genitalium in sexual health clinics ^[21]:

Key points from the STD teaching lecture ^[21]:

• First-line for NGU/cervicitis: doxycycline 1-week course
• Non-responding → M. genitalium NAAT; presumptive azithromycin-based regimen
• If still non-responding → moxifloxacin-based regimen according to MG result
• Always check adherence and alternative causes (e.g., "ping-pong infection")
• Observe for contraindications for individual drugs especially in females of reproductive age ^[21]

Specific M. genitalium treatment (resistance-guided where available):

• Macrolide-susceptible: Doxycycline 100 mg BD × 7 days (to reduce bacterial load), then Azithromycin 1 g day 1, then 500 mg days 2–4
• Macrolide-resistant: Doxycycline 100 mg BD × 7 days, then Moxifloxacin 400 mg daily × 7 days
• Moxifloxacin is a fluoroquinolone — contraindicated in pregnancy (cartilage toxicity in animal studies) and carries risk of tendinopathy, QT prolongation, and hepatotoxicity

Contraindications to topical oestrogen: Breast cancer (oestrogen-receptor positive), endometrial cancer, undiagnosed vaginal bleeding. However, ultra-low dose preparations have minimal systemic absorption and may be used with oncologist agreement.

• Remove the foreign body under speculum examination → resolution is usually rapid
• If secondary infection → treat with antibiotics (typically metronidazole for anaerobic overgrowth)
• In children → may require examination under anaesthesia

• Occurs in 0.5–3% of untreated gonococcal infections
• Purulent arthritis OR triad of tenosynovitis, dermatitis, polyarthralgia ^[24]
• Other: endocarditis, meningitis, osteomyelitis (rare)