Rescreening in gynecologic cytology. Rescreening of 3762 previous cases for current high-grade squamous intraepithelial lesions and carcinoma--a College of American Pathologists Q-Probes study of 312 institutions

Abstract

Objective: To quantitate, characterize, and analyze errors identified in the rescreening of previous gynecologic cytology specimens with original diagnoses of "within normal limits" or "benign cellular changes" for current cases diagnosed as carcinoma or high-grade squamous intraepithelial lesion.

Design and setting: College of American Pathologists Q-Probes laboratory quality improvement study in 312 laboratories.

Main outcome measure: False-negative rate in cases rescreened as a result of a current cytologic diagnosis of carcinoma or high-grade squamous intraepithelial lesion.

Results: During the examination and reporting of 1,741,515 current Papanicolaou smear cases, participating laboratories rescreened a total of 3762 previous cases that were originally diagnosed, during the 5 years prior to the current case, as being within normal limits or having benign cellular changes. For the rescreened cases, the overall false-negative rates were 10.1% using a narrow definition and 19.7% using a broad definition. The majority of errors for cases originally diagnosed as within normal limits were screening errors, while interpretive errors predominated in those cases originally diagnosed as having benign cellular changes. Eighty-six percent of all false negatives were identified in those previous cases that were originally diagnosed and reported in the 3 years prior to the current case.

Conclusions: Rescreening of previously reported smears, in patients with current abnormal findings, as one component of a complete quality improvement program, identifies errors that may provide information that will enable a laboratory to improve future performance.