An audit of the positive predictive value of high-grade dyskaryosis in cervical smears: 2001–2002

The positive predictive value (PPV) of high-grade dyskaryosis for cervical intraepithelial neoplasia grade 2 (CIN2) or worse on histology is published annually for the laboratories in the UK National Health Service Cervical Screening Programme (NHSCSP). The PPV fell in 2001 compared with 2000 for four of the five consultants reporting cervical smears in our laboratory, the greatest fall being from 91.6% to 77.9%. Investigation of the possible reasons for the fall suggested the main cause lay outside the laboratory in the type of biopsy taken at colposcopy. We conclude that biopsy type affects accuracy of PPV calculations. There is variation in collection and submission of KC61 data including PPV across laboratories. This factor needs to be taken into account when publishing and comparing laboratory data for the NHSCSP.