Inflammation / parasites
Trichomonas vaginalis

Author: John Philip, M.D. (see Authors page)
Editor: Ziyan T. Salih, M.D.

Revised: 28 August 2015, last major update August 2015

Copyright: (c) 2003-2015, PathologyOutlines.com, Inc.

PubMed Search: Trichomonas vaginalis [title] cervix
Definition / General
  • Trichomonas vaginalis is a parasitic protozoan that causes trichomoniasis, a sexually transmitted disease
  • Epidemiology
  • 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
  • Sites
  • Female: vagina, cervix, urethra and occasionally Bartholin's gland
  • Male: urethra, epididymis and prostate
  • 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
  • Diagnosis
  • 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
  • 50 year old woman with "cannon balls or pus balls" in pap smears (J Clin Diagn Res 2013;7:1715)
  • Flagella-bearing bare Trichomonas vaginalis nuclei in Papanicolaou smears (Diagn Cytopathol 1988;4:87)
  • Treatment
  • Metronidazole or tinidazole
  • Sexual partners must also be treated
  • Clinical Images
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    Strawberry cervix

    Micro 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)
  • Micro Images
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    Trichomonas in wet mount

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    Trichomonas in conventional pap smear

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    Trichomonas with leptothrix

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    Trichomonas vaginalis with leptothrix

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    Reactive squamous cells

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    SurePath prep

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    Various images

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    Contributed by Dr. Marilin Rosa

    Electron Microscopy Images
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    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