Quality control measures for cervical cytology laboratories.

The results of three quality control measures for evaluating a cytopathology laboratory's performance in the diagnosis of cervical abnormalities are presented. The sensitivities of cervical cytology were estimated to be 95.5% or 93.1% (using two different methods of analysis) for the detection of histologically diagnosed invasive squamous cell carcinoma of the cervix and 60% for the detection of adenocarcinoma and adenosquamous carcinoma of the cervix in 1983. The positive predictive values for a histologic diagnosis of neoplasia after cytologic reports of CIN III and invasive carcinoma were 92.5% and 99%, respectively. Repeatability of a negative cytologic result exceeded 98%. These results indicate that accurate cervical cytologic reporting can be achieved. Regular monitoring of the type described, which is both practical and reasonably comprehensive, is recommended for all laboratories.