NEGATIVE CYTOLOGY PRECEDING CERVICAL-CANCER - CAUSES AND PREVENTION

Aim-To assess the validity of negative cervical smear reports in women who subsequently developed cervical cancer; and to determine means of improving the screening process. Methods-One hundred and forty cervic al smears, initially reported as negative from 103 women, and taken up to 12 years before diagnosis of cervical cancer, were reviewed. Resul ts-Ninety two smears contained dyskaryotic cells. Analysis showed that these smears formed several well defined patterns. False negative rep orts were likely to occur if fragments of neoplastic tissue rather tha n dissociated dyskaryotic cells were present or if the smear contained few dyskaryotic cells. Screening fatigue appeared to be a factor in o thers. It was also considered important that smears contained cells fr om the endocervix. These were deficient in 64% of the 47 smears confir med as negative on review and in 69% of smears containing only a few d yskaryotic cells. Conclusions-Current methods of quality assurance wil l not remedy these defects in the screening process. It is the respons ibility of laboratories to identify sources of poor smears and liaise with smear takers to ensure an improvement in quality. Assessment of t he quality of smears received by a laboratory should become an importa nt part of audit. Staff training should place more emphasis on the int erpretation of ''microbiopsies''. The adoption of a quick scanning tec hnique before conventional screening would probably also substantially reduce false negative results.