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Bethesda ’01 questionnaire results: How cervical cytology reporting rates have changed

May 2004

Diane D. Davey, MD

The results are in!

Many cytologists have been asking when new benchmarking data will be available for Bethesda 2001 cervical cytology categories. The 2003 Pap program supplementary questionnaire focused on Bethesda 2001 implementation and reporting rates for conventional smears and liquid-based preparations. The survey was mailed to the 1,751 laboratories enrolled in the Interlaboratory Comparison Program in Cervicovaginal Cytopathology, or Pap program, in mid 2003, and 759 laboratories returned the questionnaire. The results show widespread acceptance of Bethesda 2001 (85.5 percent), with most laboratories implementing the revised terminology in 2002 or earlier.1

The new specimen adequacy categories and criteria are widely used, and most labs have eliminated the benign cellular changes category. A slight majority (56 percent) routinely use educational notes in reports. The Laboratory Accreditation Program includes a phase I question (CYP.07582) about educating providers that cervical cytology is a screening test with inherent false-negative results. An educational note is the preferred mechanism, but conferences and newsletters are other means to satisfy this accreditation requirement.

The majority of laboratories that responded offered both conventional and liquid-based cervical cytology testing in 2002 (66.3 percent). The results for all specimens indicate a slight increase in average low-grade squamous intraepithelial lesion, or LSIL, detection compared with the previous questionnaire survey from 1997.2,3 The median LSIL rate was 1.6 percent in 1996, compared with 2.1 percent in 2002, while 95th percentile reporting rates were identical (6.0 percent). In contrast, high-grade squamous intraepithelial lesion, or HSIL, detection rates show little change in distribution, with a 0.5 percent median in both surveys. The 1996 median reporting rate for atypical squamous cells, or ASC, was 4.5 percent, with 95 percent of laboratories reporting ASC rates of 13 percent or less. The 2003 survey divided ASC into the ASC-US and ASC-H categories. Corresponding median reporting rates were 3.9 percent and 0.2 percent, for an estimated total median ASC rate of about 4.1 percent. The 95th percentile reporting rates were 10.4 percent for ASC-US and 2.0 percent for ASC-H. Reporting rates for atypical glandular cells were low in both years, with a median of 0.3 percent in 1996 and 0.2 percent in 2002.

An ASC/SIL ratio was calculated for laboratories that provided reporting rates for ASC and SIL. The calculation is the percentage of ASC-US plus ASC-H cases divided by the sum of LSIL, SIL, and HSIL+ (HSIL plus cancer) cases. The median ASC/SIL ratio was 1.4 in 2002, lower than the 2.0 median ratio from 1996. The ASC/SIL ratio also showed a more narrow distribution in 2002, with 95 percent of laboratories having an ASC/SIL ratio of 3.4 or less, compared with a 95th percentile ratio of 5.1 in 1996.

Squamous epithelial abnormality rates appear to be higher for both types of liquid-based preparations, or LBPs, compared with conventional smears. The median LSIL rate for LBP was 2.4 percent compared with 1.4 percent for conventional smears. Median ASC-US, ASC-H, and HSIL rates were also slightly higher for both LBPs, though differences were less pronounced. Because of the impact of the higher LSIL rates, the median ASC/SIL was slightly lower for LBP (1.3 compared with 1.4 for conventional smears). The 95th percentile ASC/ SIL ratio was 3.1 for LBP, less than the 95th percentile ratio of 3.7 for conventional smears.

The median unsatisfactory cervical cytology rate for all specimen types was 0.5 percent in 2002, identical to the 1996 rates. Liquid-based preparations tended to show slightly lower unsatisfactory rates (0.4 percent median for ThinPrep and 0.2 percent for SurePath). Many experts predicted that unsatisfactory rates would increase as the more strict objective Bethesda 2001 criteria were implemented. The lack of change in unsatisfactory rates reported in this questionnaire may reflect improved sampling and specimen preparation or lack of attention to strict Bethesda 2001 criteria.

The CAP accreditation checklist will incorporate these new benchmarking data.3 Given the slight differences in smears and liquid-based preparations, two tables of data will be provided to participating laboratories. Full summaries of the questionnaire results will be mailed soon to laboratories enrolled in the Pap program.

References

  1. Solomon D, Davey D, Kurman R, et al. The 2001 Bethesda System. Terminology for reporting cervical cytology. JAMA. 2002;287:2114-2119.
  2. Davey DD, Woodhouse S, Styer P, et al. Atypical epithelial cells and specimen adequacy. Current laboratory practices of participants in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytology. Arch Pathol Lab Med. 2000;124: 203-211.
  3. Cytopathology Laboratory Accreditation Checklist, available at: http://www.cap.org.

Dr. Davey, past chair of the CAP Cytopathology Committee, is professor of pathology and laboratory medicine and laboratory director of the cytopathology and bone marrow laboratories, University of Kentucky Chandler Medical Center, Lexington.