Condom use and vaginal Y-chromosome detection: the specificity of a potential biomarker.

Objective: Detection of vaginal Y-chromosome sequences (YCS) may be a useful biomarker to validate sexual behavior reporting in women. We describe the effects of condom use on the detection of vaginal YCS.

Methods: Fifty-six women were asked to abstain from sexual intercourse for 14 days. On day 15, participants were asked to engage in sexual intercourse with their male partners using condoms. Self-collected vaginal swabs were obtained on days 14, 16, and 17. YCS were detected using the Roche LightCycler with the use of positive controls.

Results: Fourty-four of 56 women completed the study. Five women (11.4%) had detectable YCS. The overall specificity of the YCS assay with condom use was 92% (95% CI: 80%-98%). Although women who reported receptive oral sex and digital penetration within 48 hours of swab collection had a higher detection rate of YCS [RR 2.3 (95% CI: 1.1-4.6) and 3.6 (95%CI: 1.6-8.5), respectively], the mean concentration of YCS was much less than that associated with unprotected vaginal intercourse (P <0.001)

Conclusions: Condom use during intercourse appears to prevent vaginal YCS detection; this may be a useful biomarker to validate self-reported condom use.