Evaluation of PAPNET system for rescreening of negative cervical smears

We rescreened 2,238 cervicovaginal smears conventionally prepared with Papanicolaou stain by PAPNET system. The slides screened manually as negative, were sent to PAPNET system. The image tapes were reviewed on a high-resolution monitor, and categorized as negative, unsatisfactory, and atypical. All atypical cases were rescreened manually. Abnormal cases were reviewed by a cytopathologist. Two-thousand one hundred and two (94%) cases rescreened by PAPNET were negative. Nine of 45 unsatisfactory cases by PAPNET were unsatisfactory by manual review. Ninety-one (4.0%) cases by PAPNET were atypical. On manual rescreening, 86 of 91 were negative, 20% showing benign cellular changes; five of 91 were atypical, the atypia, however, not exceeding low-grade category. The detection rate by PAPNET method was 0.2% (five of 2,238 cases). We conclude: 1) In a cytology laboratory with good quality control, PAPNET rescreening does not significantly increase the detection rate. 2) For cytology laboratories without in-house rescreening, PAPNET offers an alternative at a price. 3) The PAPNET system also offers a tool by which a laboratory can occasionally monitor its performance. 4) The cost benefit analysis of the system requires further study and scrutiny.