A b s t r a c t Rapid (30-second) prescreening of cervicovaginal smears can be used to detect false-negative cases and determine the false-negative rate of primary screening, hut the performance characteristics have not been evaluated fully. A test set of 242 cases includingRapid prescreening of cervicovaginal smears is a quality control measure that has been practiced predominantly in the United Kingdom. Unlike the rescreening of 10% of cervicovaginal smears that is required of laboratories in the United States, this method involves prescreening 100% of all smears, but for only 30 seconds each. The results of this prescreening are recorded and used to identify any falsenegative cases that result from the full screening that occurs subsequently. Although the sensitivity of rapidly prescreening a case is lower than that of traditional screening without a time limit, rapid prescreening allows more cases to be reviewed in the same amount of time, which results in the detection of more false-negative cases compared with 10% rescreening.'~5 For example, the sensitivity of rapid screening for a diagnosis of atypical squamous cells of undetermined significance (ASCUS) is only about 30% to 50% that of routine screening or rescreening. 35 -6 But because rapid screening is approximately 5 to 10 times faster than routine rescreening, it detects more false-negative cases than does routine rescreening.In addition, rapid prescreening is a better method than routine rescreening for determining the false-negative rate (FNR) of primary screening. To accurately measure the FNR. it is necessary to determine the FNR of the method used to find false-negative cases, whether routine rescreening or rapid prescreening.7 Since rapid prescreening, by design, includes a review of all specimens, both positive and negative, the positive specimens can be used as controls to calculate the FNR. By contrast, incorporating known positive controls in routine rescreening is difficult and may not be practical. Nevertheless, the performance characteristics of rapid screening have not been completely characterized. Although

A b s t r a c t In the Bethesda