In suspected trichomoniasis, what is the initial diagnostic test?

• A. Vaginal culture
• B. KOH prep
• C. Biopsy
• D. Clinical diagnosis

Answer: (B)

In suspected trichomoniasis, you diagnose by looking for the organism directly in vaginal discharge. The initial test is a saline (wet) mount of the vaginal swab or discharge to see motile Trichomonas trophozoites. This quick, bedside approach can confirm infection when organisms are visualized, though its sensitivity can be limited. If the wet mount is negative but suspicion remains, use a more sensitive test such as a nucleic acid amplification test (NAAT) on a vaginal swab, which has high sensitivity and specificity. Culture can also detect Trichomonas but takes longer, and biopsy isn’t used for this diagnosis. Note that a KOH prep is used to diagnose fungal vaginitis and not Trichomonas.