Trichomonas vaginalis is a highly motile, flagellated protozoan parasite. Trichomoniasis is a sexually transmitted infection (STI).

Features

• vaginal discharge: offensive, yellow/green, frothy
• vulvovaginitis
• strawberry cervix
• pH > 4.5
• in men is usually asymptomatic but may cause urethritis

Investigation

• microscopy of a wet mount may show motile trophozoites
  • low sensitivity of around 50% but high specificity
• nucleic acid amplification tests (NAATs) are now regarded as the diagnostic gold standard for Trichomonas
  • sensitivity: >95–99%, specificity: >98–100%

Trichomonas vaginalis - largely transparent core with finely granular eosinophilic cytoplasm. Surrounded by neutrophils with segmented nuclei

Management

• oral metronidazole for 5-7 days, although the BNF also supports the use of a one-off dose of 2g metronidazole

Compare with:

Comparison of bacterial vaginosis and Trichomonas vaginalis