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Trichomoniasis

By

Sheldon R. Morris

, MD, MPH, University of California San Diego

Reviewed/Revised Jan 2023
View PATIENT EDUCATION

Trichomoniasis is infection of the vagina or male genital tract with Trichomonas vaginalis. It can be asymptomatic or cause urethritis, vaginitis, or occasionally cystitis, epididymitis, or prostatitis. Diagnosis is by direct microscopic examination, dipstick tests, or nucleic acid amplification tests of vaginal secretions or by urine or urethral culture. Patients and sex partners are treated with metronidazole or tinidazole.

Trichomonas vaginalis is a flagellated, sexually transmitted protozoan that more often infects women than men; in the US in 2013–2016, among individuals ages 14 to 59 years, prevalence was 2.1% among women and 0.5% among men (1 Reference Trichomoniasis is infection of the vagina or male genital tract with Trichomonas vaginalis. It can be asymptomatic or cause urethritis, vaginitis, or occasionally cystitis, epididymitis... read more ). Infection may be asymptomatic in either sex. In men, the organism may persist for long periods in the genitourinary tract without causing symptoms and may be transmitted to sex partners. Trichomoniasis may account for up to 5% of nongonococcal, nonchlamydial urethritis in men in some areas.

Reference

  • 1. Flagg EW, Meites E, Phillips C, et al: Prevalence of trichomonas vaginalis among civilian, noninstitutionalized male and female population aged 14 to 59 years: United States, 2013 to 2016. Sex Transm Dis 46(10):e93-e96, 2019. doi:10.1097/OLQ.0000000000001013

Symptoms and Signs of Trichomoniasis

In women, symptoms of trichomoniasis range from none to copious, yellow-green, frothy vaginal discharge with a fishy odor, and soreness of the vulva and perineum, dyspareunia, and dysuria. Asymptomatic infection may become symptomatic at any time as the vulva and perineum become inflamed and edema develops in the labia. The vaginal walls and surface of the cervix may have punctate, red “strawberry” spots. Urethritis and possibly cystitis may also occur.

Men are usually asymptomatic; however, sometimes urethritis results in a discharge that may be transient, frothy, or purulent or that causes dysuria and frequency, usually early in the morning. Often, urethritis is mild and causes only minimal urethral irritation and occasional moisture at the urethral meatus, under the foreskin, or both. Epididymitis and prostatitis are rare complications.

Diagnosis of Trichomoniasis

  • Vaginal testing with nucleic acid amplification tests (NAATs), wet-mount microscopic examination, rapid-antigen dipstick tests, or sometimes culture or cervical cytology

  • Culture of urine or urethral swabs from men

In women, one of the following diagnostic tests of vaginal secretions may be done:

  • NAAT

  • Vaginal pH and wet mount microscopy

  • Immunochromatographic flow dipstick test

NAATs are more sensitive than microscopic examination or culture for diagnosis of trichomoniasis in women. Immunochromatographic flow dipstick tests are also available for point of care testing in women. Cervical cytology (Pap test) is not used to test for trichomoniasis, but infection is sometimes detected incidentally.

Microscopic examination enables clinicians to evaluate for trichomoniasis and bacterial vaginosis Bacterial Vaginosis (BV) Bacterial vaginosis is a dysbiosis, a complex alteration of vaginal flora, in which lactobacilli decrease and anaerobic pathogens overgrow. Symptoms include a yellow-green or gray, thin, malodorous... read more Bacterial Vaginosis (BV) at the same time, because they cause similar symptoms and/or may coexist. Vaginal secretions are obtained from the posterior fornix. The pH is measured. Secretions are then placed on 2 slides; they are diluted with 10% potassium hydroxide on one slide (KOH wet mount) and with 0.9% sodium chloride on the other (saline wet mount). For the whiff test, the KOH wet mount is checked for a fishy odor, which results from amines produced in bacterial vaginosis Bacterial Vaginosis (BV) Bacterial vaginosis is a dysbiosis, a complex alteration of vaginal flora, in which lactobacilli decrease and anaerobic pathogens overgrow. Symptoms include a yellow-green or gray, thin, malodorous... read more Bacterial Vaginosis (BV) . The saline wet mount is examined microscopically as soon as possible to detect trichomonads, which can become immotile and more difficult to recognize within minutes after slide preparation. (Trichomonads are pear-shaped with flagella, often motile, and average 7 to 10 micrometers—about the size of white blood cells—but occasionally reach 25 micrometers.) If trichomoniasis is present, numerous neutrophils are also present. Trichomoniasis is also commonly diagnosed by seeing the organism when a Papanicolaou (Pap) test is done.

Culture of urine or urethral swabs is the only validated test for detecting T. vaginalis in men. In men, microscopy of urine is insensitive, and NAATs are not currently cleared by the FDA but could be available if local laboratories have done internal validation studies.

As with diagnosis of any STI, patients with trichomoniasis should be tested to exclude other common STIs such as gonorrhea and chlamydia.

Treatment of Trichomoniasis

  • Oral metronidazole or tinidazole

  • Treatment of sex partners

Women with trichomoniasis should receive metronidazole 500 mg orally twice a day for 7 days. Men should receive metronidazole 2 g orally in a single dose. An alternative treatment for women and men is tinidazole 2 g orally in a single dose.

If infection persists in women and reinfection by sex partners has been excluded, women should be retreated with metronidazole 500 mg twice a day for 7 days or tinidazole 2 g orally once a day for 7 days.

Metronidazole may cause leukopenia, disulfiram-like reactions to alcohol, or candidal superinfections. It is relatively contraindicated during early pregnancy, although it may not be dangerous to the fetus after the 1st trimester. Tinidazole has not been established as safe during pregnancy and so is not used.

Sex partners should be seen and treated for trichomoniasis with the same regimens based on sex and should be screened for other STIs. If poor adherence to follow-up by sex partners is likely, treatment can be initiated in sex partners of patients with documented trichomoniasis without confirming the diagnosis in the partner.

Key Points

  • Trichomoniasis can be asymptomatic, particularly in men, or cause vaginitis or sometimes urethritis.

  • In women, diagnose by microscopic examination of vaginal secretions, dipstick tests, or NAATs.

  • In symptomatic men, diagnose by culture of urine, urethral swab, or possibly NAATs.

  • Treat patients and their sex partners with oral metronidazole or tinidazole.

Drugs Mentioned In This Article

Drug Name Select Trade
Flagyl, Flagyl ER, Flagyl RTU, LIKMEZ, MetroCream, MetroGel, MetroGel Vaginal, MetroLotion, Noritate, NUVESSA, Nydamax, Rosadan, Rozex, Vandazole, Vitazol
Tindamax
4-Way Saline, Adsorbonac, Altamist, Ayr Allergy & Sinus, Ayr Baby Saline, Ayr Saline Nasal, BD Posiflush Normal Saline, BD Posiflush Sterile Field Normal Saline, BD Posiflush SureScrub Normal Saline, Blairex Broncho Saline, Breathe Free Saline, Deep Sea , Entsol, HyperSal, Hyper-Sal, Hypertears, Little Remedies for Noses, Little Remedies Stuffy Nose, Monoject Sodium Chloride, Muro 128, NebuSal , Ocean, Ocean Complete, Ocean For Kids, Pediamist, PULMOSAL, Rhinaris, Rhinaris Lubricating, Saljet , Saljet Rinse, SaltAire, Sea Soft, Trichotine, Wound Wash, XYNASE, ZARBEE'S Soothing Saline Nasal Mist
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NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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