Quality indices in a cervicovaginal cytology service: before and after laboratory accreditation

Quality assurance practices contribute to the effectiveness of cervical screening and are formalized by participation in a laboratory accreditation program.

To identify changes in the quality indices of our cervicovaginal cytology service preceding and following laboratory accreditation by the College of American Pathologists in 2000.

Cervicovaginal cytology quality indices for 2001 (postaccreditation) were compared with those of 1997 (preaccreditation). Performances in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology (PAP) for the years 1999-2002 were analyzed.

A comparison between data for 1997 and 2001 shows the following: (a) a higher inadequacy rate (1.3% vs 0.7%; P <.001) in 2001; (b) maintenance of a low atypical squamous cells of undetermined significance-squamous intraepithelial lesion ratio (0.79 and 0.76, respectively); (c) overall positive predictive values of positive cytology of 82% and 87%, respectively; (d) relatively few changes to the original cytologic diagnoses following review of significant cytohistologic discrepancies (4 cases and 2 cases, respectively); and (e) a higher subsequent positive yield of squamous intraepithelial lesions following atypical squamous cells of undetermined significance diagnoses in 2001 (41% vs 19%; P =.02). The performance of the laboratory and cytotechnologists in the PAP program showed maintenance of a high standard with almost no major discrepancies recorded.

An increased awareness of quality-related issues and participation in intradepartmental consultation/diagnostic seminars, all part of the accreditation process, have very likely contributed to the modest improvements identified in the cytology service. Future challenges include increases in workload with the anticipated launch of Singapore's national cervical screening program and adaptation to the emerging cervical screening technologies.