Effectiveness of automated cervical cytology rescreening using the AutoPap 300 QC System

This study assesses the performance of the AutoPap 300 QC System in identifying false-negative (FN) smears in a slide population previously screened as normal and compares the detection rate to that achieved with a random rescreen of the same slide population. A total of 1,840 "normal" smears were rescreened both manually and by the AutoPap 300 QC System. Overall, a total of 7 FN slides were detected. At QC selection rates of 30% and 20% the device achieved sensitivities for detection of FN smears of 57.19% (4/7) and 42.8% (3/7), respectively. This represents a three- to fourfold enrichment in the number of FN smears over that obtained by a random rescreen of a similar proportion of cases. None of the FN slides were identified by either method at a 10% rescreening rate. The ability of the device to detect slides previously classified as abnormal (n = 139) and FN (n = 40) was also studied. The overall sensitivity to abnormal smears at QC selection rates of 10%, 20%, and 50% was 61.9%, 77.0%, and 94.2%, respectively. Improved sensitivity to smears classified as LSIL or worse (n = 112) was obtained for corresponding selection rates (61.6%, 75.9%, and 93.8%). Sensitivity to FN slides classified as LSIL or worse (n = 17) for QC selection rates of 10%, 20%, and 50% was 29.4%, 70.6%, and 88.2%, respectively. The sensitivity and specificity of the device to an adequate squamous and endocervical cell component was also determined. At predetermined thresholds, the overall sensitivity to slides with an inadequate squamous cell component (n = 55) and to those smears with an endocervical cell component (n = 1.587) was 81.8%, and 82.7% respectively. The study demonstrated that the AutoPap 300 QC System is superior to human random rescreen for the identification of FN smears although only a marginal improvement was noted due to the small sample. Further studies are required using a larger number of smears to fully assess the value of the device in quality control mode. The device also has the potential to improve the accuracy of specimen adequacy determinations and to serve as a useful adjunct to existing quality control measures designed to monitor individual performance and reporting accuracy.