To determine if concomitant high-risk human papillomavirus (HPV-HR) reflex testing may bias the cytologic interpretation of Papanicolaou (Pap) tests.
Percentage of atypical squamous cells of undetermined significance (ASCUS) and HPV-HR positivity was compared between Pap tests with HPV-HR cotesting and HPV-HR reflex testing for ASCUS, with subset analysis of cytopathologists' experience.
ASCUS in the reflex group (41.5%) was significantly higher than the cotesting group (33.0%) (P = .02). There was no difference in HPV-HR positivity or ASCUS/squamous intraepithelial lesion (SIL) ratios between the two groups. The cytopathologists' experience inversely correlated with the proportion of ASCUS but did not explain the higher reflex group ASCUS.
HPV-HR reflex testing may introduce bias in cytologic diagnosis, making it more likely that an ASCUS diagnosis is rendered. HPV-HR and ASCUS/SIL ratios were similar between the groups, so cytopathologist performance was not significantly affected. There was no effect of cytopathologists' experience.