Improving accuracy in gynecologic cytology. Results of the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology.

The College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology (PAP) is a quarterly mailed glass-slide quality improvement program. This growing program started as a pilot in 1989 with 207 laboratories. In 1991, 605 laboratories participated. The diagnostic menu is modified from the Bethesda System and divides referenced slides into a negative series (normal, infectious, and reactive) and a positive series of epithelial lesions. A facsimile option facilitates immediate educational feedback. The 1989 through 1991 major discrepancy rate averaged 5%. The consensus laboratory response had higher concordance than either pathologist or cytotechnologist responses. Low-grade squamous intraepithelial lesion was the leading cause of false-negative participant response, while reactive/reparative change was the leading cause of false-positive response. Pathologist false-negative and false-positive responses from group or large case-volume practices were significantly lower than those from solo or small case-volume practices. Cytotechnologists in multiple-technologist or large-volume laboratories had significantly lower false-negative responses than solo technologists or those in low case-volume laboratories, but false-positive rates did not differ. Experienced participants had fewer major discrepancies. The Interlaboratory Comparison Program in Cervicovaginal Cytology illustrates the feasibility of a large, mailed glass-slide program, and offers laboratories a continuous method for monitoring and improving performance in gynecologic cytology.