Vulvovaginitis Workup

Updated: Dec 07, 2022
  • Author: Jill M Krapf, MD, MEd, FACOG, NCMP, IF; Chief Editor: Christine Isaacs, MD  more...
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Approach Considerations

Laboratory evaluation, if indicated, for a patient with vulvovaginitis includes checking vaginal pH and performing microscopy. [23] Fungal culturing may be used if the diagnosis of vulvovaginal candidiasis is uncertain. [1]

Vulvovaginal candidiasis

The diagnosis depends on the demonstration of a species of Candida --as with a wet-mount test or potassium hydroxide (KOH) preparation—and the presence of clinical symptoms. Vaginal pH usually remains normal in vulvovaginal candidiasis. [27, 28] (See the image below.)

Candida albicans photomicrograph. Courtesy of Cent Candida albicans photomicrograph. Courtesy of Centers for Disease Control and Prevention (CDC).

Most studies demonstrate that 85-90% of vaginal isolates in vulvovaginal candidiasis are C albicans. As a result, fungal cultures have not been used by most clinicians as part of the initial evaluation. Moreover, there is a concern that fungal cultures are too sensitive and will detect yeast that may be colonizing the patient but not causing symptoms.

Atrophic vaginitis

History and physical examination generally provide sufficient information to diagnose atrophic vaginitis. Vaginal pH, if performed, generally is 6-7. A wet mount often shows white blood cells and a paucity of Lactobacillus. Culture and a KOH preparation usually are unrewarding.


Vaginal pH

Measurement of vaginal pH using Nitrazine paper is the single most important finding that drives the diagnostic process and should always be determined. Vaginal pH can be tested using a narrow-range pH paper. A pH above 4.5 suggests infections such as bacterial vaginosis or trichomoniasis (pH 5-6) and helps to exclude vulvovaginal candidiasis (pH 4-4.5). [3, 23, 29]

Remember, the specimen should be obtained in the mid-vagina, usually the side walls, and not the posterior fornix, since that area is contaminated by alkaline cervical mucus. Vaginal pH testing can be carried out by the patient; studies have shown good agreement between patient- and doctor-performed testing. [30, 31]


Wet-Mount Test

The wet-mount test involves microscopic examination of vaginal discharge or scrapings from vulvar lesions mixed with physiologic saline, using low- and high-power magnifications. Under microscopic viewing, the spores and conidia are visible. The presence of yeast blastospores or pseudohyphae can be detected in approximately 30-50% of patients with symptomatic vulvovaginal candidiasis. [17, 23]

A KOH preparation is made by placing a drop of vaginal secretion on a slide with a drop of 10-20% KOH and using a coverslip to protect the microscope lens. This technique is particularly useful in the diagnosis of candidal vaginitis, since the preparation may reveal budding filaments, mycelia, or pseudohyphae.

Adding KOH to the solution lyses white blood cells, red blood cells, and vaginal epithelial cells, making the alkali-resistant branching budding hyphae of Candida easier to see. Although this method may increase the sensitivity of the examination, however, it produces negative findings in at least one third of patients with symptomatic candidiasis. Nevertheless, positive results in combination with a normal vaginal pH, are helpful in confirming the diagnosis.