Preparatory Mindset
Female genital tract infections are the most common gynaecological presentations in clinic and a reliable OSCE station: abnormal vaginal discharge, pruritus, pelvic pain, or fever. The exam mindset is a discharge differential driven by three parameters: colour/consistency, pH, and microscopy (wet mount + KOH). Master the big four vaginitides (candida, trichomonas, bacterial vaginosis, aerobic vaginitis), then cervicitis/PID (the ascending infection — sequelae: infertility, ectopic, chronic pelvic pain), and the STI panel (chlamydia, gonorrhoea, syphilis, HSV, HPV) (2018CM exam tested). The theme: identify the organism (or syndrome), treat the organism and the partner, and remember the complications — PID can silently destroy fertility.
Core Concepts
1. Normal vaginal ecosystem and defences
- Lactobacilli dominate — produce H₂O₂ and lactic acid → vaginal pH 3.8-4.5 (acidic).
- Defences: acidic pH, cervical mucus plug (closed internal os — mechanical barrier), cervical mucus (antibacterial), menstruation/desquamation, commensal flora.
- Disturbance (antibiotics, hormones, douching, sexual activity) → overgrowth of pathogens.
2. The vaginitides — clinical comparison
| Feature | Candida (VVC) | Trichomonas (TV) | Bacterial vaginosis (BV) | Aerobic vaginitis (AV) |
|---|---|---|---|---|
| Pathogen | *Candida albicans* (~80-90%) | *Trichomonas vaginalis* (protozoan, lives on glycogen/iron) | Polymicrobial (Gardnerella, anaerobes; ↓lactobacilli) | Aerobic bacteria (E. coli, group B strep) |
| Discharge | White, curdy, "cottage cheese" | Yellow-green, frothy, malodorous | Thin, grey-white, fishy odour (worse after sex) | Purulent, yellow-green |
| Pruritus | Intense | Marked (worse at night) | Mild | Moderate |
| Other | Vulvovaginal erythema, satellite lesions | Strawberry cervix (punctate haemorrhages); dyspareunia, dysuria | No inflammation (often asymptomatic) | Erythema, ulceration |
| pH | 4.0-4.5 (normal) | >4.5 (5-6) | >4.5 | >4.5 |
| Microscopy | KOH: budding yeast + pseudohyphae | Wet mount: motile trichomonads | Clue cells (epithelial cells covered in bacteria) | No clue cells; leukocytes, parabasal cells |
| Whiff test | Negative | Positive (fishy, amine) | Positive (fishy) | Variable |
| Treatment | Azole (clotrimazole, fluconazole) — topical/PO; 14 days if RVVC | Metronidazole 2 g single dose (or 400-500 mg bid × 7 days) — treat partner too | Metronidazole (or clindamycin) — oral/topical; partner NOT treated | Antibiotic per culture (e.g., clindamycin + steroid) |
Special notes:
- Trichomoniasis in pregnancy: metronidazole allowed (with informed consent) — treats symptoms and prevents preterm birth.
- Recurrent vulvovaginal candidiasis (RVVC ≥4/year): prolong induction (e.g., 14 days) + maintenance (fluconazole weekly × 6 months); check partners only if symptomatic.
- BV is not an STI — asymptomatic partners don't need treatment; BV in pregnancy — screen/treat symptomatic (links to PPROM/preterm).
- Asymptomatic candidiasis/BV in pregnancy: generally don't treat unless symptomatic (exceptions per guidelines).
3. Cervicitis
Definition: inflammation of the cervix — mucopurulent discharge from the os, cervical motion tenderness (but no uterine/adnexal tenderness).
Causes: Chlamydia trachomatis (most common), Neisseria gonorrhoeae, Mycoplasma genitalium, HSV, HPV (warty), Trichomonas.
Management: test (NAAT chlamydia/gonorrhoea; HSV PCR if ulcers) + empiric treatment: doxycycline 100 mg bid × 7 days (chlamydia) + ceftriaxone 500 mg-1 g IM (gonorrhoea) + azithromycin alternatives; treat partner, screen other STIs (syphilis, HIV), counsel, and repeat test of cure for chlamydia/gonorrhoea in pregnancy or persistent infection.
4. Pelvic inflammatory disease (PID)
Definition: ascending infection of the upper genital tract — endometritis, salpingitis, oophoritis, tubo-ovarian abscess, peritonitis.
Causes: Chlamydia + gonorrhoea (common), Mycoplasma, anaerobes, endogenous flora; polymicrobial.
Risk factors: age <25, multiple partners, previous PID/STI, IUCD insertion (first 3 weeks), recent instrumentation, menstruation.
Clinical (classic): bilateral lower abdominal pain + cervical motion tenderness + uterine/adnexal tenderness (the minimum criteria — 3 of 3); fever; abnormal cervical/vaginal discharge; dyspareunia; abnormal uterine bleeding. Red flags: RUQ pain (Fitz-Hugh-Curtis — perihepatitis), tubo-ovarian abscess (mass), peritonitis.
Diagnosis: clinical (minimum criteria) + endocervical NAAT (chlamydia/GC), elevated ESR/CRP, USS (free fluid, tubo-ovarian mass), laparoscopy (gold standard).
Complications (the exam punchline): tubal factor infertility (10-20%), ectopic pregnancy (6×), chronic pelvic pain (20%), tubo-ovarian abscess, Fitz-Hugh-Curtis.
Management:
| Severity | Treatment |
|---|---|
| Outpatient (mild-moderate) | Ceftriaxone 500 mg-1 g IM single + doxycycline 100 mg bid × 14 days ± metronidazole 400-500 mg bid × 14 days; treat partner; test of cure; return if worsens |
| Inpatient (severe/pregnant/immunocompromised/abscess) | IV antibiotics (cefoxitin/ceftriaxone + doxycycline ± metronidazole; or clindamycin + gentamicin); analgesia; drain tubo-ovarian abscess (IV antibiotics + USS-guided drainage or laparoscopy) |
| Follow-up | 48-72 h reassessment (improvement); test of cure for gonorrhoea/chlamydia; STI screening + partner notification; contraception counselling; avoid intercourse until treated |
PID prevention: STI screening, condoms, avoid IUCD in active PID (insert when treated), screening young women (chlamydia).
5. STI essentials (gynaecology lens)
| STI | Key features | Treatment |
|---|---|---|
| Chlamydia | Often asymptomatic; mucopurulent cervicitis; tubal damage (silent) | Doxycycline 100 mg bid × 7 days (azithromycin alternative); test of cure |
| Gonorrhoea | Purulent cervicitis, urethritis; PID; disseminated (arthritis-dermatitis) | Ceftriaxone 500 mg-1 g IM (plus chlamydia cover); test of cure |
| Syphilis | Primary chancre (painless), secondary rash (palms/soles), tertiary (neurosyphilis, gumma) | Benzathine penicillin (dose per stage); pregnancy — penicillin mandatory (avoid doxycycline) |
| HSV-2 | Painful vesicular ulcers; recurrent | Aciclovir/valaciclovir (episodic or suppression); C-section if active lesions at delivery |
| HPV | Genital warts; cervical intraepithelial neoplasia → cervical cancer (types 16/18) | Vaccination (9-valent); treat warts (cryo, imiquimod); cervical screening (HPV ± cytology) |
| Trichomonas | See above | Metronidazole |
High-Yield Points
| Topic | Must-remember |
|---|---|
| Normal pH | 3.8-4.5 (lactobacilli) |
| Candida | Curdy white + intense pruritus; KOH pseudohyphae; azole |
| Trichomonas | Frothy yellow-green + strawberry cervix; motile on wet mount; metronidazole + treat partner |
| BV | Thin grey fishy + clue cells; metronidazole/clindamycin; partner not treated |
| BV + pregnancy | Links to PPROM/preterm — treat symptomatic |
| Cervicitis | Chlamydia most common; doxycycline + ceftriaxone |
| PID criteria | Cervical motion tenderness + uterine tenderness + adnexal tenderness (all 3) |
| PID outpatient | Ceftriaxone + doxycycline ± metronidazole × 14 d |
| PID sequelae | Infertility, ectopic, chronic pelvic pain |
| Fitz-Hugh-Curtis | RUQ pain + PID (perihepatitis) |
| Syphilis in pregnancy | Benzathine penicillin (mandatory) — prevent congenital syphilis |
| HPV | 16/18 → cervical cancer; vaccine |
| HSV at delivery | Active lesions → C-section |
Topic Summary
Vaginal discharge is triaged by colour, pH, and microscopy: candida (curdy, pH 4, pseudohyphae → azole), trichomonas (frothy, pH 5-6, motile → metronidazole + partner), BV (fishy, clue cells → metronidazole/clindamycin, no partner treatment), AV (purulent → culture-guided). Cervicitis (chlamydia/gonorrhoea) is treated with doxycycline + ceftriaxone. PID (all 3: cervical motion + uterine + adnexal tenderness) causes infertility/ectopic/chronic pain and is treated with ceftriaxone + doxycycline ± metronidazole, with hospital admission for severe cases/abscess. STI screening + partner treatment + vaccination (HPV) close the loop.
LMCHK OSCE Practice — Vaginal Discharge Station
Station setup: A 24-year-old woman presents with 3 days of profuse yellow-green frothy vaginal discharge and itching. Speculum: cervix erythematous with strawberry spots, thin yellow-green discharge pooling. Wet mount shows motile organisms. She asks about treatment and whether her partner needs treatment.
Candidate tasks (8 min):
- Diagnose trichomoniasis (classic discharge + strawberry cervix + motile trichomonads).
- Explain the condition (STI — protozoan) and need to treat the partner (metronidazole 2 g single dose both).
- Discuss metronidazole: alcohol avoidance (disulfiram-like reaction), pregnancy safety (consent).
- Screen for other STIs (chlamydia, gonorrhoea, syphilis, HIV) — co-infection common.
- Advise: complete the course, partner treated, abstain until both cured, recheck if symptoms persist; test of cure in pregnancy.
Key marking cues:
- Identifies trichomoniasis from discharge + wet mount.
- Treats partner (unlike BV).
- Screens for co-existing STIs.
- Counsels on metronidazole + alcohol interaction.
- Handles pregnancy/consent considerations.
Companion — PID recognition:
A 26-year-old with bilateral lower abdominal pain, cervical motion tenderness, uterine + bilateral adnexal tenderness, and mucopurulent discharge, no fever.
- Diagnose PID (all 3 minimum criteria).
- Outpatient regimen: ceftriaxone 500 mg-1 g IM + doxycycline 100 mg bid × 14 d ± metronidazole.
- Admit if: pregnant, immunocompromised, tubo-ovarian abscess, septic, failed oral therapy.
- Counsel: infertility/ectopic risk, complete the course, partner treatment, test of cure.