Vaginal swabs best compared to urine testing for diagnosing various STDs among women

The Centers for Disease Control and Prevention suggests that vaginal swabs are the best form of sample for women being tested for gonorrhea, chlamydia, and/or trichomoniasis compared to urine testing. This study was published in The Annals of Family Medicine.

The two most common sexually transmitted infections (STIs) that must be reported in the United States are Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG), while Trichomonas vaginalis (TV), despite not being a disease that must be reported, is the most prevalent curable non-viral STI worldwide. These illnesses affect women disproportionately, and testing is required to detect infections. Although vaginal swabs are the suggested sample type, urine is the specimen that women utilize the most frequently. The goal of the study by Kristal Aaron and colleagues were to compare the diagnostic sensitivity of commercially available tests for female urine specimens and vaginal swabs.

Studies that met the following criteria: (1) employed a reference standard; (2) assessed commercially available assays; (3) reported results for women; (4) contained data from the same test on both a urine specimen and a vaginal swab from the same patient; (5) were published in English. For each pathogen, pooled values for sensitivity and the related 95% confidence intervals (CIs) as well as odds ratios for any performance differences were determined.

The key findings of this study were:

With 30 CT comparisons, 16 NG comparisons, and 9 TV comparisons, 28 qualifying articles were found. 

94.1% and 86.9% for CT, 96.5% and 90.7% for NG, and 98.0% and 95.1% for TV were the pooled sensitivity estimates for vaginal swabs and urine, respectively (all P values.001).

Nevertheless, for TV, the OR that vaginal swabs were more sensitive than urine did not achieve statistical significance. The pooled sensitivity for vaginal swabs was consistently higher than that of urine. Nevertheless, if a fixed effects model was employed, the OR that vaginal swabs were more sensitive than urine was statistically significant. This is because TV had a small sample size and moderate to high heterogeneity, thus researchers were cautious in employing a random effects model.

Reference: 

Aaron, K. J., Griner, S., Footman, A., Boutwell, A., & Van Der Pol, B. (2023). Vaginal Swab vs Urine for Detection of Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis: A Meta-Analysis. In The Annals of Family Medicine (Vol. 21, Issue 2, pp. 172–179). Annals of Family Medicine. https://doi.org/10.1370/afm.2942