Letters to the Editor

Case Report: Efficient and Cost-Effective Diagnosis of Vaginitis


Am Fam Physician. 2019 Mar 15;99(6):344.

To the Editor: A 27-year-old woman presented with vaginal odor and increased discharge. Her physician was in a hurry and instead of completing a wet mount test, ordered a nucleic acid amplification test (NAAT). The results were negative. The cost of the examination was nearly $1,000, with $295 being the patient's responsibility.

Vaginal symptoms are some of the most common reasons for outpatient visits. Physicians often use microscopy, pH, and whiff tests in addition to history and physical examination findings to aid in diagnosis because culture is not always readily available or timely. NAAT, however, provides laboratory results with less diagnostic effort and tests for the most common infectious etiologies with one swab. How does the diagnostic accuracy of NAAT compare with traditional clinical diagnosis?

Bacterial vaginosis is the most common cause of vaginitis, with Gardnerella as the most common organism. Bacterial vaginosis is commonly diagnosed if three out of four Amsel criteria (vaginal pH greater than 4.5; positive whiff test; clue cells present on microscopy; and thin, homogenous white discharge on vaginal examination) are met. Although the specificities of the Amsel criteria and NAAT for bacterial vaginosis are similar, the sensitivity of the Amsel criteria is only 60% for bacterial vaginosis, compared with 90.5% for NAAT.1

Candida, most commonly Candida albicans, is the second most common cause of vaginitis. Microscopy to evaluate for hyphae and vaginal pH less than 4.5 have a sensitivity of 50% to 80% for predicting yeast as the cause of infection and cannot distinguish between different organisms within the Candida genus.2 The sensitivity and specificity of NAAT swabs for Candida were 90.9% and 94.1%, respectively.1

Trichomoniasis, the least common type of infectious vaginitis, is caused by the protozoan Trichomonas. Although microscopy has a specificity of nearly 100% for Trichomonas, its sensitivity is only 60% to 70%.2 The Centers for Disease Control and Prevention, therefore, considers NAAT the preferred test.3

Given the evidence, NAAT is a good test for all three organisms, although it may lead to higher costs and more false-positive results in patients with low pretest probabilities of infection.4 In routine cases of vaginitis, it is reasonable to treat based on microscopy results, reserving NAAT for patients at risk of trichomoniasis or with resistant or recurrent symptoms. Studies commonly employ rigorous microscopy protocols not common in day-to-day practice; therefore, physician education could minimize the limitations of microscopy.5 Regarding the case study presented here, an improved clinical decision-making tree could have avoided an unnecessary bill and financial stress for the patient.

Author disclosure: No relevant financial affiliations.

The author thanks Kenny Lin, MD, MPH, for his mentorship during her research project related to this letter.


show all references

1. Gaydos CA, Beqaj S, Schwebke JR, et al. Clinical validation of a test for the diagnosis of vaginitis. Obstet Gynecol. 2017;130(1):181–189....

2. Mylonas I, Bergauer F. Diagnosis of vaginal discharge by wet mount microscopy: a simple and underrated method. Obstet Gynecol Surv. 2011;66(6):359–368.

3. Workowski KA, Bolan GA; Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015 [published corrrection appears in MMWR Recomm Rep. 2015;64(33):924]. MMWR Recomm Rep. 2015;64(RR-03):1–137.

4. Klausner JD. The NAAT is out of the bag. Clin Infect Dis. 2004;38(6):820–821.

5. Lowe NK, Neal JL, Ryan-Wenger NA. Accuracy of the clinical diagnosis of vaginitis compared with a DNA probe laboratory standard. Obstet Gynecol. 2009;113(1):89–95.

Send letters to afplet@aafp.org, or 11400 Tomahawk Creek Pkwy., Leawood, KS 66211-2680. Include your complete address, e-mail address, and telephone number. Letters should be fewer than 400 words and limited to six references, one table or figure, and three authors.

Letters submitted for publication in AFP must not be submitted to any other publication. Possible conflicts of interest must be disclosed at time of submission. Submission of a letter will be construed as granting the AAFP permission to publish the letter in any of its publications in any form. The editors may edit letters to meet style and space requirements.

This series is coordinated by Kenny Lin, MD, MPH, Associate Deputy Editor for AFP Online.



Copyright © 2019 by the American Academy of Family Physicians.
This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. Contact afpserv@aafp.org for copyright questions and/or permission requests.

Want to use this article elsewhere? Get Permissions


May 2022

Access the latest issue of American Family Physician

Read the Issue

Email Alerts

Don't miss a single issue. Sign up for the free AFP email table of contents.

Sign Up Now

Navigate this Article