Cervical cytopathology. An evaluation of its accuracy based on cytohistologic comparison

Although Papanicolaou cytology represents the most effective technique to prevent and detect precancerous conditions of the uterine cervix, its false-negative yield is still a reason of concern among pathologists and gynecologists.

Because histologic control is one of the best ways to assess the accuracy of cytology diagnosis, the authors have investigated 1000 women who had cervical smears and tissue sampling obtained during the same colposcopic evaluation between 1987 and 1990.

Out of 1000 cases (average age, 34.6 years; range, 14-80 years), 918 had adequate, 62 had less than optimal, and 10 had unsatisfactory samples. Cytology unsatisfactory and less than optimal cases as well as inadequate histology cases have been disregarded from all calculations. After histologic comparison, confirmed negatives were 622 of 918 (67.8%). Cytologic diagnoses of cervical intra-epithelial neoplasia (CIN) I were 96, of CIN II were 44, of CIN III, inclusive of carcinoma in situ, were 39, and of invasive carcinoma were 2. Atypical cases were 56. The overall sensitivity was 76.3%, with group sensitivity rates increasing directly with CIN grade. Positive predictive value was 80.2%. Specificity was 93.0%, and negative predictive value was 91.3%. False-negatives were 59 of 681 (8.7%), basically due to sampling errors. Among true-positives, there was 1 category discrepancy in 30 cases (mostly undercalled or overcalled CIN II) and 2 category discrepancies in 4 cases.

Cervical cytology has an overall accuracy close to that reported in studies employing indirect control methods, such as patient follow-up. Higher sensitivity rates emerged for CIN II, CIN III, and cervical carcinoma. Our figures of sensitivity and specificity may represent a useful reference source for future studies dealing with quality control in cervical cytopathology.