Medicine & USMLE

Trichomonas vaginalis

  1. Giardia lamblia
  2. Toxoplasma gondii
  3. Entamoeba histolytica
  4. Cryptosporidium
  5. Naegleria fowleri
  6. Trypanosoma brucei
  7. Plasmodium Overview
  8. Plasmodium Disease (Malaria)
  9. Babesia
  10. Trypanosoma cruzi
  11. Leishmania
  12. Trichomonas vaginalis
  13. Enterobius vermicularis (pinworm)
  14. Ascaris lumbricoides (giant roundworm)
  15. Strongyloides stercoralis (threadworm)
  16. Ancylostoma and Necator
  17. Trichinella spiralis
  18. Trichuris trichiura (whipworm)
  19. Toxocara canis
  20. Onchocerca volvulus
  21. Loa loa
  22. Wuchereria bancrofti
  23. Taenia solium
  24. Diphyllobothrium latum
  25. Echinococcus granulosus
  26. Schistosoma
  27. Clonorchis sinensis
  28. Sarcoptes scabiei (Scabies)
  29. Pediculus humanis and Phthirus pubis (Lice)


Trichomonas vaginalis, also shortened as Trichomonas or simply “trick”, is a flagellated parasite that is sexually transmitted. A Trichomonas infection is formally called trichomoniasis, and includes vaginitis, characterized by a yellow-green colored vaginal discharge. Trichomoniasis can also present with cervicitis with the appearance of a “strawberry cervix” on speculum exam. 

Trichomonas can be diagnosed by wet mount microscopy, in which the vaginal discharge discussed earlier is prepared on a slide, revealing motile trichomonads or swimming flagellated parasites.

The first line treatment for trichomonas is metronidazole.

Key Points

  • Trichomonas vaginalis
    • Characteristics
      • Flagellated protozoan parasite
    • Transmission
      • Sexually transmitted
        • Coinfection with other STIs is common
        • Look for history of multiple sexual partners without protection
    • Presentation: Trichomoniasis
      • Vaginitis
        • Parasite infects squamous epithelium in vaginal mucosa
        • Yellow-green vaginal discharge
          • May be foul-smelling
          • Contrast vs. Gardnerella, which causes grey-white discharge
        • Itching, burning, and other discomfort may be seen
        • Vaginal pH may be elevated
      • Urethritis may be seen in men
    • Diagnosis
      • Motile trichomonads on wet mount (saline) microscopy
        • Flagellated pear-shaped or round organisms with jerky and spinning movements are seen
      • PCR/NAAT
        • Used when microscopy is inconclusive but trichomonas is still suspected
      • Strawberry cervix
        •  Bright red inflamed cervix seen on speculum exam
    • Treatment
      • Metronidazole for patient and partner
        • Tinidazole may also be used
          • Causes less GI side effects, but more expensive