Interobserver variability in the cytological diagnosis of 1500 Papanicolaou stained cervical monolayer specimens

Cervical specimens from 1500 patients were prepared by means of a centrifugation procedure to obtain monolayer specimens suitable for automated screening using a machine. After staining according to Papanicolaou, each specimen was diagnosed by four independent cytologists from two different institutes. Within each institute, noncorresponding screening results were discussed to arrive at a conclusion diagnosis. After discussion of the discrepancies between the two centers, the conclusion diagnoses were combined to one final cytological diagnosis for each specimen. This final diagnosis is to be used as a reference diagnosis to evaluate machine classification as obtained by the AUTOPLAN/MIAC system. This system is presently being tested both in Leiden and in Frankfurt for its accuracy of detecting abnormal lesions in cervical specimens. The used diagnostic procedure resulted in a negative reference diagnosis for 1217 of the 1500 specimens; 170 specimens were diagnosed CIN I or II (mild or moderate dysplasia) and 113 specimens had a positive reference diagnosis (CIN III or invasive carcinoma). Based on these three diagnostic classes, the agreement between the four independent cytologists and the reference diagnosis varied between 93.60% and 96.60%, whereas 95.33% of all 6000 diagnoses correlated with the reference diagnosis.