Trichomoniasis
Clinical presentation
- Woman - symptoms : characteristic leucorrhoea (profuse vaginal discharge + greenish-yellow + frothy + malodorous - fishy or camembert odour) + intense vulvar and vaginal pruritus + burning + dyspareunia + dysuria + vulvar erythema + the characteristic picture (green discharge + frothy + intense pruritus + fishy odour) is very suggestive but present in only 20-30 % of symptomatic women + many have less characteristic leucorrhoea or are asymptomatic
- Uterine cervix - strawberry sign (macular colpitis) : strawberry cervix erythema on colposcopy or sometimes with the naked eye → pathognomonic but present in only 2-5 % of cases + non-specific if observed in isolation
- Men - symptoms : most often asymptomatic (70-85 %) → main reservoir of trichomoniasis + if symptomatic: urethritis (clear or mucoid urethral discharge + urinary burning) + prostatitis + epididymitis (rare) + asymptomatic men remain infectious and represent the main vector of reinfection for women
- Pregnancy: associations with premature delivery + premature rupture of membranes + low birth weight + treatment recommended even during pregnancy (metronidazole safe after 1st trimester)
Diagnosis
- NAAT (nucleic acid amplification test - PCR) : current reference method + sensitivity 95-100 % + specificity 95-100 % + can be performed on vaginal + cervical + urethral swabs + or first-draft urine + available in reference laboratories and sexual health clinics + test of choice for screening asymptomatic patients
- Fresh examination (wet preparation) : direct microscopic visualization of motile trophozoites (characteristic tendril-like movement) + sensitivity 50-70 % (decreases rapidly if sample not analyzed immediately) + specificity 95-99 % + immediate clinical results + performed on fresh vaginal secretions + limited usefulness in men
- Culture (Diamond medium): historical gold standard + sensitivity 85-95 % + 5-7 day delay + little used in routine clinical practice since the advent of NAATs
- Rapid antigen test (OSOM Trichomonas) : sensitivity 83-95 % + specificity 97-100 % + results in 10 minutes + available in point-of-care + useful if NAAT not available
- Vaginal pH : increased (> 4.5) in trichomoniasis (as in bacterial vaginosis) → not very specific but indicative
- Systematic screening recommended : any woman with leucorrhoea + vaginal pruritus + or full STI screening + HIV positive + recent STI + multiple sexual partners
Differential diagnosis of leucorrhoea
| Cause | Appearance of leucorrhoea | pH | Microscope | Diagnostic test |
|---|---|---|---|---|
| Trichomoniasis | Yellow-green + foamy + smelly | > 4,5 | Flagellate motile trophozoites | TAAN + fresh state |
| Bacterial vaginosis | Gray + fluid + homogeneous + fishy odor (amine) | > 4,5 | Clue cells + no leukocytes | Amsel + NAAT criteria |
| Vaginal candidiasis | White + thick + lumpy + cottage cheese | < 4.5 (normal) | Hyphae + pseudohyphae + spores | Fresh state + fungal culture |
| Cervicitis (chlamydia + gonorrhea) | Mucopurulent + sensitive neck | Variable | Abundant polymorphism | TAAN neck or urine |
| Physiological leucorrhoea | Whitish + clear + odorless + fluctuating with the cycle | < 4,5 | Epithelial cells + lactobacilli | None (diagnosis of exclusion) |
Treatment
- Metronidazole 2 g po single dose (treatment of choice) : efficacy 84-98 % + simultaneous treatment of sexual partner(s) mandatory + sexual abstinence during treatment + up to 7 days after single dose (or until both partners have completed treatment) + avoid alcohol during treatment and 24 hours afterwards (antabuse reaction: nausea + vomiting + flush)
- Tinidazole 2 g po single dose (alternative) : same efficacy as metronidazole + better digestive tolerance + fewer gastrointestinal side effects + avoid alcohol 72 hours after use (longer half-life) + slightly more expensive
- Alternative if intolerant to single dose : metronidazole 500 mg × 2/day × 7 days + or tinidazole 500 mg × 2/day × 7 days → more side effects but may be better tolerated on the stomach
- Pregnancy: metronidazole 2 g single dose → safe after 1st trimester (reassuring data) + or metronidazole 500 mg × 2/d × 7 d + treatment recommended because obstetrical complications (prematurity) associated with untreated trichomoniasis are significant
- Partner treatment : MANDATORY + treatment of all sexual partners in the last 60 days + simultaneously if possible + notification of partners by patient or public health + without treatment of partner → re-infection rate 17-38 % at 3 months
- Metronidazole resistance : rare (2-5 % of cases) → higher-dose tinidazole (2 g/day × 5 days) + or metronidazole 2 g/day × 3-5 days + infectiology consultation if resistance confirmed
- Test of cure : not systematic if symptoms resolved + treatment of confirmed partner + consider if symptoms persist → NAAT 2-4 weeks after treatment (not earlier - possible false positives on residual DNA)
Consult a doctor if unusual leucorrhoea (yellow-green + frothy + malodorous) + intense vaginal pruritus + or urinary burning appear + particularly after unprotected intercourse - full STI screening (NAAT for trichomoniasis + chlamydia + gonorrhoea + HIV serology + syphilis) enables diagnosis and initiation of effective treatment. Sexual partners must be treated simultaneously to prevent reinfection. For complete STI screening and treatment prescription, Clinique Omicron offers medical consultations at its points of service in Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron's specialized physicians and nurse practitioners (NPNs) perform NAAT screening for trichomoniasis as part of complete STI check-ups, prescribe metronidazole 2 g single dose with instructions on simultaneous partner treatment, perform the associated complete STI check-up (HIV + chlamydia + gonorrhea + syphilis + hepatitis B), advise on prevention of reinfection (abstinence during treatment + condoms), and provide follow-up if symptoms persist. Consultations are available at several points of service in Quebec, and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The contents of this page are provided for information purposes only and do not replace medical advice. Simultaneous treatment of sexual partner(s) is essential to prevent reinfection - without this treatment, relapses are very frequent. Avoid alcohol during treatment with metronidazole and 24 hours (metronidazole) or 72 hours (tinidazole) after the last dose.
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