Vaginal swabs are slightly more sensitive than urine samples for detecting chlamydia, gonorrhea, or trichomoniasis in women

Reference

Aaron KJ, Griner S, Footman A, Boutwell A, Van Der Pol B. Vaginal swab vs urine for detection of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis: A meta-analysis. Ann Fam Med 2023;21(2):172-179.

Synopsis

These authors searched several databases and registries to identify English-language studies that compared vaginally collected samples and urine samples against an externally performed assay and a nucleic acid amplification test as the reference standard. Although the studies could include adolescents, these authors excluded any studies that only evaluated children. They included 28 studies but don’t report on methodologic quality (eg, consecutive sampling, masking, independent application of the reference standard, and so forth) nor on the number of participants in each study. The included studies that used several different assays as well as different specific nucleic acid amplification tests. The authors only report the sensitivities (see table) for the various collection methods and provide no explanation for not reporting the specificities. My assumption is that the authors were only concerned with using these tests for screening purposes (where highly sensitive tests are desirable to “rule out” disease) rather than for diagnosing symptomatic infections. This is curious since they comment on the inclusion of symptomatic patients in the studies. By not including the data on test specificity, we don’t really have a sense of the overall diagnostic accuracy of the 2 collection methods.

Vaginal sample sensitivity
 
(95% CI)

Urine sample sensitivity
 
(95% CI)