Vaginal Discharge
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Direct answer
Three bedside tools — colour and consistency, vaginal pH (normally 3.8-4.5), and microscopy of a wet mount — separate the common infective causes of abnormal vaginal discharge: bacterial vaginosis (thin grey-white homogenous discharge, pH above 4.5, clue cells, positive whiff test with 10 per cent KOH, treated with metronidazole 400 mg twice daily for seven days), vulvovaginal candidiasis (thick curdy discharge with itch, pH below 4.5, budding yeast, treated with fluconazole 150 mg single dose or topical azoles), and trichomoniasis (frothy green discharge, pH 5-6, motile flagellates, strawberry cervix, treated with metronidazole 2 g single dose with partner treatment). In India, many facilities manage discharge syndromically under the National Health Mission's programme, treating multiple organisms at one visit when testing is unavailable.
What you must remember
- Normal discharge is white, odourless and non-irritating, maintained by lactobacilli that keep pH at 3.8-4.5; a cyclical increase near ovulation is not disease.
- Bacterial vaginosis — Gardnerella and anaerobe overgrowth replacing lactobacilli; Amsel criteria (three of four): homogenous thin discharge, pH above 4.5, positive amine whiff test with KOH, clue cells on wet mount; associated with preterm birth and postoperative infection.
- Vulvovaginal candidiasis — Candida albicans in most; intense itch, curdy plaques, erythema, pH below 4.5; risk factors are diabetes, antibiotics, pregnancy and immunosuppression; treatment is fluconazole 150 mg once or azole pessaries.
- Trichomoniasis — Trichomonas vaginalis, a sexually transmitted flagellate; frothy greenish discharge with dysuria and the strawberry cervix in a minority; treat patient and partner with metronidazole 2 g single dose.
- Mixed infections are common, and desquamative inflammatory vaginitis (high pH with parabasal cells) deserves mention when the triad fails.
- Red flags changing the pathway — mucopurulent discharge with a friable cervix points to chlamydia or gonorrhoea needing NAAT; foul discharge with fever suggests pelvic inflammatory disease; blood-stained or postcoital discharge demands speculum examination and cervical screening.
- Indian programme frame — syndromic case management under NACO or NHM guidelines uses pre-packed kits covering candidiasis, trichomoniasis and bacterial vaginosis at one visit, because point-of-care microscopy is often unavailable.
- Recurrent BV is managed with suppressive metronidazole; recurrent candidiasis (four or more a year) needs a diabetes screen and maintenance fluconazole.
- Non-infective causes — retained foreign body (a forgotten tampon in adults), cervical ectopy and chemical irritants; these explain discharges that fail repeated antibiotics.
Diagnosing at the bedside in five minutes
A 24-year-old attends with a fortnight of discharge and itch. Three questions: itch (severe), odour (her partner noticed one), antibiotics (a course of amoxicillin last month). Speculum examination shows white plaques on an erythematous vagina plus a thin grey pool of fluid.
The pH strip is the fork in the road. A pH of 4.2 with curdy plaques says candida, confirmed by budding yeast on microscopy — precipitated by her antibiotic course, a classic exam scenario. The grey pool that smells of amines with KOH is a second disease alongside: bacterial vaginosis, with clue cells clinching it. She receives fluconazole 150 mg once plus metronidazole 400 mg twice daily for a week — treating both, which real practice demands often.
Contrast two neighbours. One has frothy green discharge, dysuria, a punctate red cervix and swimming flagellates on wet mount — trichomoniasis, so metronidazole 2 g single dose for her and her partner. The other, a 37-year-old with blood-tinged discharge and postcoital spotting after years of no screening, has an irregular cervix — her pathway is cervical screening and biopsy; missing this is the gravest error in the topic.
Where students slip
The pH ladder is the most fumbled fact — candidiasis keeps the pH acidic (below 4.5), while bacterial vaginosis and trichomoniasis push it above 4.5 — and students routinely invert it. The whiff test belongs to BV, the strawberry cervix to trichomoniasis, and neither to candida; itch belongs mainly to candida. Partner treatment is remembered for trichomoniasis but wrongly extended to candida. Finally, repeated courses without a speculum examination miss foreign bodies and cervical disease — the exam answer for a non-responding discharge is examination and microscopy.
Frequently asked questions
How does vaginal pH differentiate the common infections?
Candidiasis keeps pH below 4.5, while bacterial vaginosis and trichomoniasis raise it above 4.5 — the fastest bedside discriminator available.
What are the Amsel criteria for bacterial vaginosis?
Three of four — homogenous thin discharge, vaginal pH above 4.5, positive amine whiff test with 10 per cent KOH, and clue cells on saline microscopy.
What is the treatment of trichomoniasis?
Metronidazole 2 g orally as a single dose (or tinidazole 2 g) for the patient and partner, with alcohol avoidance during and 24-48 hours after therapy.
How is recurrent vulvovaginal candidiasis approached?
Four or more episodes a year — screen for diabetes and immunosuppression, confirm the species, and use induction fluconazole followed by weekly maintenance for about six months.
When should vaginal discharge trigger cervical evaluation?
When it is blood-stained, mucopurulent with a friable cervix, or associated with postcoital bleeding — especially in an unscreened woman over 30.