Trichomonas vaginalis

Overview

•Discharge - frothy, yellow-green, offensive; raised pH (>4.5)

•Vulval itching and irritation - local inflammatory response

•Dysuria - urethral colonisation present in up to 90% of women

•Strawberry cervix (colpitis macularis) - punctate haemorrhagic spots; visible to naked eye in ~2% but pathognomonic when present

🎯

Strawberry cervix = Trichomonas vaginalis. It is NOT a feature of bacterial vaginosis - a direct and repeated exam question.

Vaginal discharge differential

Feature	TV	BV	Candidiasis
Discharge	Frothy, yellow-green	Thin, grey-white	Thick, white 'cottage cheese'
Odour	Offensive	Fishy	None
Itch	Yes	No	Prominent
Vaginal pH	>4.5	>4.5	<4.5 (normal)
Microscopy	Motile trichomonads	Clue cells	Hyphae/spores
Causative organism	Trichomonas vaginalis (protozoan)	Gardnerella vaginalis (bacterium)	Candida albicans (fungus)

Investigations

🥇 First-line

•high vaginal swab (HVS) - wet mount microscopy for motile trichomonads; sensitivity ~50-70%

🏆 Gold standard

•NAAT - highest sensitivity and specificity; recommended by BASHH 2021

•Vaginal pH - >4.5 supports TV (or BV)

•Screen for co-existing STIs - chlamydia, gonorrhoea, syphilis, HIV

Management

🥇 First-line

•metronidazole 400-500 mg orally twice daily for 5-7 days - preferred; higher cure rates

•Alternative: metronidazole 2 g orally as a single dose - if adherence is a concern

🥈 Second-line

•tinidazole 2 g orally as a single dose - for metronidazole intolerance or treatment failure

•Partner management - all recent sexual partners must be traced, tested, and treated simultaneously; re-infection from untreated partner is the most common reason for treatment failure

•Abstain from sexual intercourse until patient and all partners have completed treatment and are asymptomatic

•Avoid alcohol during metronidazole and for 48 hours after - disulfiram-like reaction

•Pregnancy: metronidazole can be used in all trimesters - use 5-7 day course rather than 2 g single dose