Inflammatory / infectious

Trichomonas vaginalis

Topic Completed: 1 August 2015

Minor changes: 4 December 2020

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PubMed Search: Trichomonas vaginalis [title] cervix

John K.S.S. Philip, M.D.
Ziyan T. Salih, M.D.
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Cite this page: Philip J, Salih Z. Trichomonas vaginalis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cervixtrichomonasvaginalis.html. Accessed December 3rd, 2021.
Definition / general
  • Trichomonas vaginalis is a parasitic protozoan that causes trichomoniasis, a sexually transmitted disease
  • Trichomoniasis is the most prevalent nonviral sexually transmitted infection in the United States, affecting an estimated 3.7 million persons (CDC - Trichomoniasis)
  • Having multiple sexual partners is the primary risk factor
  • Mainly affects women from ages 16 - 35 years, but can occur in postmenopausal women
  • Female: vagina, cervix, urethra and occasionally Bartholin's gland
  • Male: urethra, epididymis and prostate
Diagrams / tables

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Clinical features
  • Most infected persons (70% - 85%) have minimal or no symptoms, and untreated infections might last for months to years (CDC - Trichomoniasis)
  • Copious yellow, green or gray, white vaginal discharge with a strong odor
  • Itching and irritation are frequent
  • Discomfort during sexual intercourse or urination
  • In pregnancy, can cause premature rupture of membranes and preterm delivery
  • Largely asymptomatic in men, act as a carrier; may cause urethritis
  • Nucleic acid amplification test (NAAT)
  • OSOM trichomonas rapid test: Immunochromatographic test that detects pathogen antigens from vaginal swab
  • DNA hybridization probe test
  • Direct microscopic examination of secretions - wet mount
  • Culture: Was considered as a gold standard before the availability of molecular tests
Prognostic factors
  • Treatment reduces the signs and symptoms of infection and might reduce transmission (CDC - Trichomoniasis)
Case reports
  • Metronidazole or tinidazole
  • Sexual partners must also be treated
Clinical images

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Strawberry cervix

Cytology description
  • Pear shaped, oval or round cyanophilic organisms, 15 - 30 microns
  • Eosinophilic cytoplasmic granules are often evident
  • Nucleus is pale, vesicular and eccentrically located
  • Flagella are sometimes observed
  • Leptothrix may be seen in association with Trichomonas vaginalis
  • Mature squamous cells with slightly enlarged, dark nuclei and small perinuclear halos ("trich change") are common that may mimic a low grade squamous dysplasia
  • 3 dimensional clusters of neutrophils ("polyballs") may be seen in the background
  • Numerous lymphocytes and many mast cells may be seen
  • Organisms tend to be smaller and rounder with better visualized nuclei, cytoplasmic eosinophilic granules and flagella in liquid based preparations
  • Neutrophils and "polyballs" are reduced in liquid based preparations compared to the conventional smears
  • Occasional kite shaped forms may be seen, especially on SurePath preparations (Nayar: The Bethesda System for Reporting Cervical Cytology, 3rd Edition, 2015)
Cytology images

Contributed by Dr. Marilin Rosa


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Trichomonas in wet mount

Trichomonas in conventional
pap smear

Trichomonas vaginalis with leptothrix



Various images

Electron microscopy images

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Missing Image

T. vaginalis parasite

Differential diagnosis
  • Cell fragments, cytoplasmic debris, bare epithelial nuclei, small mucus aggregates and leukocytes:
    • Identification of a definite elliptical nucleus helps avoid misinterpretation
    • Presence of eosinophilic cytoplasmic granules will be helpful
    • In most cases, trichomonad organisms are plentiful ("trich party")
      • Therefore, a rare fragment of cyanophilic debris is not likely to be a true trichomonad
Additional references
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