What is the role of saline wet mount microscopy in the diagnosis of trichomoniasis?

Updated: Jan 02, 2020
  • Author: Darvin Scott Smith, MD, MSc, DTM&H; Chief Editor: Michael Stuart Bronze, MD  more...
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In women, vaginal trichomoniasis has historically been diagnosed via wet mount microscopy, which has very low sensitivity (25%) for detecting T vaginalis compared with most molecular tests. [98] Although it is not the criterion standard technique for trichomoniasis diagnosis, wet mount is frequently used because it is quick, inexpensive, and easy to perform. [57, 12, 13] The absence of trichomonads on microscopy does not rule out a diagnosis of vaginal trichomoniasis. Because they involve the direct visualization of the trichomonads, wet mounts are more likely to return positive results in women with high organism loads. [2] Wet mount microscopy is not an effective test for the diagnosis of trichomoniasis in men. Saline wet mount evaluation is performed by placing a small amount of vaginal discharge on a microscope slide and mixing with a few drops of saline solution. The slide is then examined under a microscope at low or medium power. See the video below.

Trichomonas vaginalis on a saline wet mount at 40X on the microscope. Several motile parasites transit through the field, surrounded by white blood cells and squamous epithelial cells.

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