Making the Most of Pap Testing

Following dramatic newspaper and television accounts that clinical laboratories often failed to detect abnormal Papanicolaou (Pap) smears, Congress amended the Clinical Laboratory Improvement Act (CLIA) in 1988. CLIA '88 included provisions designed to reduce the false-negative rate for Pap smears by detecting and correcting deficiencies in laboratory procedures. Most laboratories have complied with the CLIA Pap smear requirements by taking a second look at ("rescreening") 10% of all Pap smears initially classified as "within normal limits."

CLIA-mandated rescreening may have stimulated laboratories to improve the quality and accuracy of testing. But when 90% of the slides read as normal are not rescreened, random rescreening can raise the overall sensitivity of testing by little. Newer approaches to reduce the false-negative rate, such as computer-based technologies to automate or assist in the interpretation of Pap smears, have the potential to do better. Automation might be expected to lower the costs and increase the accuracy of both initial screening and rescreening. Unlike human beings who examine smear after smear in rapid succession, computerized devices are not subject to fatigue or distraction. In this issue of THE JOURNAL, O'Leary and colleagues assess whether these potential advantages of computer-assisted interpretation of Pap smears are real. They examine PAPNET, a computerized system that is applied to all smears classified on initial manual screening as normal, and that selects the subset with suspicious areas for manual review.