Clinical Laboratory Improvement Amendments of 1988 (CLIA '88) regulations specify that at least 10% of negative Papanicolaou (Pap) slides be rescreened as a quality control (QC) measure. With incorporation of human papillomavirus (HPV) DNA testing into screening guidelines for women aged 30 years or older, a population of patients exists who are HPV positive as well as negative for intraepithelial lesion or malignancy (NILM).
In this 9-month retrospective review with follow-up, 26,501 women 30 years of age and older underwent liquid-based Pap screening with concomitant high-risk HPV DNA testing at CellNetix Pathology and Laboratories, Seattle, WA. Of these women, 1,096 (4.1%) were originally interpreted by cytotechnologists as NILM with HPV DNA positivity.
On rescreening, 13.9% (152/1,096) of patients were upgraded to atypical squamous cells and higher, with 2.8% being upgraded to low-grade squamous intraepithelial lesion (LSIL) and higher. Historical routine QC measures from the same period showed that 0.3% of cases were upgraded to LSIL and higher, representing a statistically significant increase in the detection of cases with LSIL and higher (χ(2) two-tailed P < .0001).
Focused rescreening of this enriched subpopulation of patients who are NILM and high-risk HPV DNA positive enhances QC. An inherent potential bias in study design is recognized because results of DNA testing were, by definition, known at the time of rescreening result interpretations.