THE SENSITIVITY OF RAPID (PARTIAL) REVIEW OF CERVICAL SMEARS

Rapid review involves a daily rapid (e.g. 30 s) review of all smears n ot normally double-screened. It has been suggested that the method may increase the sensitivity of cervical cytology by identifying abnormal ities not reported on initial screening, true false negatives (TFN). R apid screening is reported to have high sensitivity for cervical neopl asia when used as a preview tool. To be effective, however, in a revie w mode it must be able to detect TFN. Several studies have found that many TFN result from factors such as low numbers of abnormal cells or subtle expression of diagnostic criteria. Studies on the sensitivity o f rapid screening for detecting TFN would therefore provide a more rel iable estimate of its value as a review tool. The sensitivity of rapid re-screening was evaluated using a test set of 200 cases. Each of 15 screeners rapidly reviewed (30 s partial screen) the set over a 2-week period. The set consisted of 129 normal, 28 low-grade squamous lesion s (CIN I), 37 high-grade lesions (CIN II, III and adenocarcinoma in si tu (AIS)) and six invasive carcinomas. The abnormals included 20 TFN c ases. The median sensitivity for abnormalities was 62%. Rapid review w as more sensitive for CIN II and CIN III (67%) and invasive carcinoma (66.7%) than for CIN I (53%). Great variation was apparent in the sens itivity for individual screeners, with a range of 41-86% for all abnor malities. The sensitivity for TFN cases varied even more (10-75%, medi an 35%) and for most screeners was significantly (P < 0.05) lower than for cases which were detected on initial screen (53-90%, median 70.6% ). Following this trial rapid review was used routinely for a period o f 3 months. In this time 11 413 cases were rapidly reviewed. This led to the full review of 415 slides (3.5%) and the identification of 16 c ases of undetected CIN (12 CIN I, three CIN II, one CIN III). Based on current estimates of our laboratory false-negative rate this represen ts between a quarter and half of the TFN cases of CIN that probably oc curred in this period. In conclusion, rapid screening is likely to be significantly less sensitive when used in a review rather than a previ ew mode. In routine practice the method requires a daily commitment of screener time, but does provide a higher yield of TFN smears than doe s random review, and allows amendment of these results prior to report ing.