Evaluation of the PAPNET system in a general pathology service

Objective: To compare the results of an automated rescreening device (PAPNET) with manual screening of Papanicolaou (Pap) smears. Design: All normal or technically unsatisfactory smears and a random sample of abnormal smears on manual screening were submitted for PAPNET rescreening. Setting: Large general pathology laboratory in Sydney between January and September 1995. Results: Of 54, 658 PAP smears classified on manual screening as normal, 266 were reclassified as abnormal after PAPNET screening (32 atypical squamous cells of uncertain significance, 217 low-grade squamous intraepithelial lesions and 17 high-grade intraepithelial lesions). Of the random sample of 1022 smears classified on manual screening as abnormal, all high-grade intraepithelial lesions (122 smears) and squamous cell carcinomas (2 smears) were also detected by PAPNET, and 112 were reclassified as normal by PAPNET (14 atypical squamous cells of uncertain significance and 98 low-grade squamous intraepithelial lesions). Histological followup confirmed 15 of the 17 smears classified as high-grade intraepithelial lesions on PAPNET screening and detected a further seven that had been classified by PAPNET as either atypical squamous cells of uncertain significance or low-grade squamous intraepithelial lesions. Conclusions: When used as a quality-control measure in a general pathology laboratory, the PAPNET automated screening system detects higher numbers of abnormal PAP smears than manual screening.