Improved quality-control detection of false-negative Pap smears using the AutoPap 300 QC system

Federally-mandated quality control (QC) in Papanicolaou (Pap) smear testing requires rescreening of 10% of negative smears, to include cases selected randomly as ic ell as smears fn,in patients that may have a higher risk for developing cervical cancer based on clinical information. FDA approach of NeoPath's AutoPap 300 QC system (NeoPath, Inc., Redmond, WA) allows practic al QC rescreening of all negatives. We tested the ability of AutoPap to hel p increase identification of detection errors compared to random 10%/high-r isk selection. From March 1-August 30, 1997 Ire utilized AutoPap/high-risk status to select cases for manual rescreen. and compared the rate of identi fication of primary screening errors ro that for the preceding year-using 1 0% random selection/high-risk status. Of 35,027 smears accessioned, 31,240 (89.1%) rr ere screened as negative and 7,965 were selected for manual resc reen, Of these, 353 were determined to be abnormal. Most abnormals identifi ed by this protocol were classified as atypical squamous or glandular cells of undetermined significance (ASCUS or AGUS). However; 59 low-grade squamo us intraepithelial lesions (LSIL) and 13 high-grade squamous intraepithelia l lesions (HSIL), many with few abnormal cells, were also identified. These results represented an increase in pickup rate of false negatives due to d etection errors of 2.3-, 2.8- and 5.6,-fold for atypical squamous ol glandu lar cells of undetermined significance, LSIL, and HSIL. respectively:,when accounting Sor the volume differences over the time period measured Our fin dings strongly support the conclusions drawn from clinical trials of the Au toPap that false negatives due to detection error can be significantly redu ced when using AutoPap as parr of a routine quality control program. (C) Wi ley-Liss. Inc.