Infectious DiseasesTier 2Approach to a presentation

Vaginal discharge

Red flags

Signs of pelvic inflammatory disease (fever, significant pelvic pain, cervical motion tenderness) or a systemically unwell patient warrant urgent assessment and empirical treatment rather than routine outpatient work-up alone
Pregnancy status should be established early, given implications for both differential diagnosis and treatment safety

Differential by mechanism

Physiological discharge (normal cyclical variation, no odour/itch/discomfort)

Bacterial vaginosis (thin, grey, fishy odour, not itchy)

Candidiasis (thick, white, curd-like, itchy/sore)

Trichomoniasis (frothy, yellow-green, malodorous, may have vulvovaginal irritation)

Chlamydia/gonorrhoea (may be asymptomatic or cause mucopurulent cervical discharge, often with concurrent lower abdominal symptoms if ascending)

Foreign body (e.g. retained tampon - malodorous discharge, consider in the differential particularly with an unusual odour)

Focused history

Discharge characteristics (colour, consistency, odour, quantity, duration), associated symptoms (itch favours candidiasis, odour favours BV/trichomoniasis, pelvic pain/fever raises PID concern), sexual history and STI risk factors, menstrual/contraceptive history, and any recent antibiotic use (candidiasis precipitant)
Pregnancy status and last menstrual period should be established given management implications

Focused examination

Speculum examination to directly visualise discharge characteristics and the cervix (mucopurulent cervicitis suggesting chlamydia/gonorrhoea, cervical motion tenderness suggesting PID)
Bimanual examination for adnexal tenderness/masses if PID is suspected; abdominal examination for signs of more significant intra-abdominal involvement

Investigation strategy

Vaginal pH testing, wet mount microscopy, and Amsel criteria assessment for bacterial vaginosis; NAAT for chlamydia/gonorrhoea; wet mount or NAAT for trichomoniasis; microscopy/culture for candidiasis if diagnosis is unclear or recurrent
Full STI screen (including syphilis serology and HIV testing) should be routinely offered given co-infection risk

Management

Bacterial vaginosis: metronidazole
Candidiasis: topical/oral azole antifungal
Trichomoniasis: metronidazole/tinidazole, with partner treatment given its STI status
Chlamydia/gonorrhoea: targeted antibiotics plus partner notification and treatment
Suspected PID: empirical broad-spectrum antibiotic therapy started promptly on clinical suspicion, without waiting for microbiological confirmation, given the reproductive consequences of treatment delay

Traps

Treating presumptively without examination/testing when the diagnosis is not clinically clear-cut, particularly missing an STI that requires partner notification

Delaying PID treatment pending microbiology results - empirical treatment should start on clinical suspicion given the fertility consequences of delay

Assuming BV/candidiasis in isolation without offering a full STI screen, given the risk of missing a concurrent treatable STI

Talk track

"Based on what you've described and what I've found on examination, this looks most consistent with [diagnosis] - I'd like to take some swabs to confirm this and screen for any other infections at the same time, and we can start treatment today while we wait for those results."

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