Are vaginal swabs comparable to cervical smears for human papillomavirus DNA testing?

OBJECTIVE Human papillomavirus (HPV) testing is widely incorporated into cervical cancer screening strategies. Current screening requires pelvic examination for cervical sampling, which may compromise participation. The acceptance could be raised by introducing testing on vaginal swabs. We explored the interchangeability of vaginal swabs and cervical smears for HPV testing, by means of a prospective study conducted in female sex workers (FSWs). Besides, we report on the occurrence of 32 different HPV genotypes in FSW with low-grade squamous intraepithelial lesion (LSIL) or high-grade squamous intraepithelial lesion (HSIL). METHODS Paired physician-collected vaginal swabs and cervical smears from 303 FSW were tested for HPV using the Abbott RealTime High-Risk HPV assay. Cervical cytology was examined on cervical smears. In case of HSIL/LSIL cytological classification (n=52), both samples were genotyped using INNO-LiPa HPV Genotyping Extra II. RESULTS The overall prevalence of high-risk (HR)-HPV was 51%. In FSW with HSIL/LSIL cervical cytology, the sensitivity and specificity of vaginal samples for the detection of HR-HPV was 100% and 70% and for probable HR-HPV 100% and 91%. The mean number of genotypes identified in vaginal samples (mean=3.5; 95% confidence interval [CI]=2.8-4.2) was significantly higher than in cervical smear samples (mean=2.6; 95% CI=2.1-3.0) (p=0.001). The most frequently encountered HR-HPV genotypes were HPV16, 31, 51, and 52. CONCLUSION As our study shows that vaginal swabs are equivalent to cervical smears for the detection of (probable) HR-HPV, vaginal swabs can be used for HPV testing in cervical cancer screening strategies. Given the acceptance of vaginal sampling, this finding offers an opportunity to boost screening coverage.