How to prepare a wet mount (wet prep)?

From the Guidelines

To obtain a wet prep, collect a vaginal sample using a cotton swab, then mix the sample with a drop of normal saline on a glass slide, and examine immediately under a microscope at 10x and 40x magnification, looking for motile trichomonads, clue cells, yeast, or white blood cells, as recommended by the American Academy of Pediatrics 1. The process of obtaining a wet prep involves several key steps to ensure accurate results.

• Collecting the sample: A cotton swab is used to collect vaginal secretions, which can be placed in a tube with 1 mL of normal saline solution and then used to prepare a glass slide for microscopic examination 1.
• Preparing the slide: The swab can be directly smeared onto the slide, after which a drop of saline or potassium hydroxide is added 1.
• Examining the sample: The wet prep should be read as soon as the pelvic examination is completed to increase the likelihood of detecting trichomonads, and the sample should be examined under a microscope at 10x and 40x magnification, looking for motile trichomonads, clue cells, yeast, or white blood cells 1. It's also important to note that the sensitivity of the wet mount can be improved by using a 10% potassium hydroxide (KOH) preparation, which can help to identify yeast not seen on the saline-solution preparation 1. Proper sample collection and handling are crucial for accurate results, and the test should be performed promptly after collection to avoid false negatives due to the loss of trichomonad motility 1.

From the Research

Obtaining a Wet Prep

To obtain a wet prep, the following steps can be taken:

• A vaginal swab specimen is collected from the posterior fornix of the vagina with a sterile swab stick during a gynecological examination 2, 3, 4
• The swab specimen is then used for direct microscopic examination, which is a cheap and fast method, although it has low sensitivity 3
• The swab specimen can also be placed in a medium, such as Kupferberg's Trichosel medium or trypticase-yeast-extract-maltose (TYM) medium, for cultivation of Trichomonas vaginalis 3, 4
• A wet-mount preparation can be made by placing a drop of saline solution on a microscope slide, adding a sample from the vaginal swab, and covering it with a coverslip 2

Diagnosis of Trichomoniasis

The diagnosis of trichomoniasis can be made using various methods, including:

• Wet mount microscopy, which has a limited sensitivity of 52% 5
• Culture methods, which are accepted as the gold standard, but can only be applied in certain centers due to the need for experienced personnel and the ability to get results within 2-7 days 3
• Polymerase chain reaction (PCR) method, which has a sensitivity of 84% and a specificity of 94% 5
• Direct staining with acridine orange and fluorescence microscopy, which has a sensitivity of 4.4% 4

Treatment of Trichomoniasis

The standard treatment for trichomoniasis is a single 2-g oral dose of metronidazole 2

• However, metronidazole resistance has been reported, and the use of PCR to detect metronidazole resistance molecularly and phenotypically may contribute to a more accurate laboratory diagnosis of the agent and update treatment protocols 3