Rescreening in gynecologic cytology. Rescreening of 8096 previous cases for current low-grade and indeterminate-grade squamous intraepithelial lesion diagnoses--a College of American Pathologists Q-Probes study of 323 laboratories

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 low-grade squamous intraepithelial lesion or squamous intraepithelial lesion of indeterminate grade.

Design and setting: College of American Pathologists Q-Probes laboratory quality improvement study in 323 laboratories.

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

Results: A total of 8096 smears performed within the 5 years preceding the current examination were rescreened. Of the rescreened cases, 284 (3.5%) were reclassified as a squamous intraepithelial lesion or carcinoma, 474 (5.9%) as atypical squamous cells of uncertain significance, 7 (0.09%) as atypical glandular cells of uncertain significance or glandular intraepithelial lesion, and 39 (0.5%) as unsatisfactory. Ninety-three percent (261/280) of all false-negative cases were identified in cases from the previous 3 years.

Conclusion: Rescreening archival cytology cases previously diagnosed as within normal limits or benign cellular changes for current cases diagnosed as low-grade squamous intraepithelial lesion or squamous intraepithelial lesion of indeterminate grade will identify screening and diagnostic errors. This may be a useful quality improvement monitor in many laboratories.