Clinical Health Updates

Rapid antigen test for yeast more sensitive than wet mount

Clinical Question:
Is a rapid antigen test more accurate than wet mount to diagnose vaginal yeast?

Bottom Line:
The detection of vaginal yeast by rapid antigen testing is feasible for office practice and more sensitive than wet mount. A negative test result, however, is not sensitive enough to rule out yeast and avoid a culture. If this test is made available over the counter, the impact on self-diagnosis and self-treatment with over-the-counter products should be evaluated.

Reference:
Chatwani AJ, Mehta R, Hassan S, Rahimi S, Jeronis S, Dandolu V. Rapid testing for vaginal yeast detection: a prospective study. Am J Obstet Gynecol 2007;196:309.e1-e4.

Study Design:
Diagnostic test evaluation

Synopsis:
Wet mount of vaginal secretions has a sensitivity of only approximately 50% to detect yeast. More accurate testing at the point of care is needed and over-the-counter availability for self-testing is being considered. These investigators recruited 104 women, including 70 who were symptomatic and 34 asymptomatic for yeast vaginitis. Women underwent a vaginal examination performed by a physician who obtained a sample of vaginal secretion, which was tested for yeast by wet mount using 10% potassium hydroxide, by culture, and by a rapid yeast detection test manufactured by Sayyon Diagnostics. Culture was the reference standard. The cost of culture was estimated at $65, the cost of the rapid antigen test was estimated at less than $10. After the examination women were asked to perform their own antigen test for yeast using the instructions provided by the manufacturer. Sensitivity was 73%, with a negative predictive value 82% in the entire group of symptomatic and asymptomatic women. Specificity was 84%, with 16% false-positives. Patient-performed antigen tests had results similar to physician-performed tests. Although it is not specifically stated that the interpretation of the wet mount and antigen test results was blinded with regard to the interpretation of the culture, we may assume this to be the case since wet mount and antigen tests were performed and interpreted by the physician who examined the patient and the culture results were interpreted by laboratory personnel.