Researchers conducted a meta-analysis of multiple databases from 1995–2021 to assess the diagnostic sensitivity of commercially available tests that use vaginal swabs versus urine specimens to detect chlamydia (CT), gonorrhea (NG), and trichomoniasis (TV). Although vaginal swabs are the recommended sample type by the CDC, the most-used specimen among women is urine.
The authors identified 28 eligible articles with 30 comparisons for CT; 16 comparisons for NG; and nine comparisons for TV.
Vaginal swabs consistently performed somewhat better than urine tests in detecting STIs; however, for trichomoniasis, the odds ratio that vaginal swabs were more sensitive than urine was not statistically significant.
For vaginal swabs and urine, respectively, pooled sensitivity estimates were:
CT: 94.1 percent and 86.9 percent
NG: 96.5 percent and 90.7 percent
TV: 98.0 percent and 95.1 percent
The differences were statistically significant for chlamydia and gonorrhea.
The authors assert that this analysis supports the CDC’s recommendation that vaginal swabs are the optimal sample type for women being tested for chlamydia, gonorrhea, and/or trichomoniasis. Relying on urine testing could result in an estimated 400,000 undetected cases of chlamydia and gonorrhea each year. While vaginal swab tests are the most sensitive for STI testing, urine testing is a reasonable alternative when swabs are not available or acceptable.
Additional implementation studies are needed to change practice patterns to use vaginal swabs rather than urine testing. Vaginal sampling should be the initial choice offered to patients and urine samples should only be considered for women for whom the collection of a vaginal sample is not acceptable.
- This press release is supported by the American Academy of Family Physicians