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Make the Diagnosis: Vaginitis

Prior Probability

Among women with vaginal symptoms, the most common diagnoses are bacterial vaginosis (34%), vaginal candidiasis (26%), and vaginal trichomoniasis (10%). The prevalence changes across regions, so clinicians should be familiar with the findings in their own clinics.

Population for Whom Vaginitis Should Be Considered

Vaginitis should be considered in any woman with concerns about a vaginal symptom that typically includes a combination of vaginal discharge, odor, irritation, or pruritus.

Detecting the Likelihood of Causes of Vaginitis

Although the presence of odor helps identify women more likely to have bacterial vaginosis versus candidiasis, no symptoms reliably identify those with trichomoniasis (see Table 52-9). Thus, unless point-of-care tests become validated, a microscopic evaluation is required for identifying clue cells (bacterial vaginosis), yeast forms (vaginal candidiasis), or trichomonads (vaginal trichomoniasis). Clinicians who do office microscopy need appropriate training to recognize the findings (; accessed June 15, 2008).

Table 52-9Likelihood Ratios of Symptoms and Microscopy for Vaginitis

Reference Standard Tests

Bacterial Vaginosis

The pragmatic reference standard consists of the Amsel criteria.2 These require 4 different tests, of which at least 3 must have positive results: (1) a thin, homogenous vaginal discharge; (2) clue cells on microscopic examination; (3) positive whiff test; and (4) vaginal pH higher than 4.5.

The reference standard test requires culture, though culture cannot distinguish between infections and colonization.


The reference standard test in clinical research studies typically requires culture. However, in clinical practice the presence of trichomonads on a saline microscopic preparation is considered diagnostic, though the absence of trichomonads does not definitively rule out the condition.

Original Article: What Is Causing This Patient's Vaginal Symptoms?

Clinical Scenarios

Case 1

An otherwise healthy 33-year-old woman presents with a complaint of foul-smelling vaginal discharge. She is sexually active with 1 male partner. This is the first time she ...

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