[The PAPNET system in the rescreening of negative cervical/vaginal smears. A study from the Imola cytology laboratory].

The rescreening of negative cervical/vaginal smears is one of the potential areas of utilization of the systems for computer-assisted cytology diagnosis. In the Imola cytology laboratory, a random sample of 1309 conventionally prepared smears that had been originally reported as negative was rescreened with the PAPNET System (Neuromedical Systems, Inc., Suffern, NY). Smears with a PAPNET diagnosis other than negative were further and independently evaluated by the staff of the laboratory and classified according to the majority report. The PAPNET rescreening confirmed the original negative diagnosis for 1188 smears (907.6/1000) and led to the detection of 46 ASCUS/LGSIL cases (35.1/1000) and 2 AGUS/HGSIL cases (1.5/1000). Seventy-three smears (55.8/1000) were interpreted as unsatisfactory. The majority report confirmed the original negative diagnosis for 42 (91%) of the 46 PAPNET diagnoses of ASCUS/LGSIL and 50 (68%) of the 73 smears interpreted as unsatisfactory. The 2 cases of AGUS/HGSIL diagnosed by PAPNET were confirmed. The detection rate of ASCUS/LGSIL decreased from 35.1/1000 to 3.1/1000 (rate ratio 0.09, 95% confidence interval [95% CI] 0.02-0.22). The rate of unsatisfactory smears decreased from 55.8/1000 to 17.6/1000 (rate ratio 0.31, 95% CI 0.20-0.47). The rate of negative smears increased from 907.6/1000 to 977.9/1000 (rate ratio 1.08, 95% CI 1.02-1.14). In conclusion, the PAPNET rescreening of negative smears brought about a low detection rate of severe cellular changes. Though greater, the detection rate of low grade changes was substantially and significantly reduced by the majority reports. At our laboratory, the PAPNET rescreening does not appear to improve the performance of conventional cytodiagnosis.