Synopsis
Diagnose Trichomonas vaginalis with an appropriate test, use effective systemic metronidazole including in pregnancy, and prevent reinfection through concurrent partner care.
- Trichomonas vaginalis is a sexually transmitted protozoan infection; many people are asymptomatic, while vaginitis can produce offensive yellow-green discharge, soreness, dysuria and a raised vaginal pH.
- Use a validated NAAT when available because symptoms and wet-mount microscopy lack sensitivity; a negative wet mount does not exclude infection.
- Give oral metronidazole 400–500 mg twice daily for seven days; the multidose course is more effective than a single 2 g dose and topical metronidazole is inadequate.
Key red flags
Pelvic or lower abdominal pain with cervical motion, uterine or adnexal tenderness requires assessment and empirical treatment for PID.
Pregnancy with pain, bleeding, contractions, fluid loss or reduced fetal movement needs urgent maternity assessment rather than routine vaginitis follow-up.
Fever, hypotension, vomiting or peritonism suggests complicated pelvic infection or another acute abdominal diagnosis.
Persistent infection after verified adherence and partner treatment requires specialist review for reinfection, test timing and possible nitroimidazole resistance. Treat current sexual partners concurrently, offer testing for chlamydia, gonorrhoea, syphilis and HIV, and avoid sex for at least one week and until the patient and partners have completed treatment and follow-up.
Ulceration, significant contact bleeding or a mass requires examination for herpes, syphilis, trauma or neoplasia.
Pelvic pain, fever, abnormal bleeding and cervical or adnexal tenderness indicate possible PID and demand broader immediate care.
Investigation priorities
Detect T. vaginalis sensitively from a vaginal or other specimen validated by the local laboratory.
Management branches
A patient presents with discharge, odour, irritation, dysuria or notification as a trichomonas contact.
- Ask privately about onset, discharge, pain, bleeding, urinary symptoms, pregnancy possibility, exposure sites, prior treatment and partner symptoms.
- Examine the vulva and cervix when appropriate, assess upper-tract tenderness, and obtain a validated trichomonas NAAT with wider STI samples.