Reproducibility of cervicovaginal ThinPrep cellularity assessment.

Criteria for judging the squamous cellularity adequacy of cervicovaginal ThinPreps using cell counts in representative fields have been proposed. We compared the interobserver reproducibility in the designation of ThinPreps as satisfactory (SAT), satisfactory but limited by (SBLB), or unsatisfactory (UNS) for interpretation. Three reviewers independently assessed 145 cervicovaginal ThinPreps accessioned from 1997-1999 at the University of Kentucky cytopathology laboratory. Scant specimens were retrieved by computer search and more cellular specimens were added to make 145. Adjacent fields on a diameter including center at 10x and 40x were counted for sufficiently preserved and unobscured cells. A specimen was designated UNS if four or more fields at 10x had less than 10 squamous cells, and SBLB if four or more fields at 40x had less than five squamous cells. All three observers agreed on the adequacy designation in 76% of cases and the overall kappa was 0.73 (near excellent). Complete interobserver agreement was present in 86% (63/73) of UNS cases, 79% (33/42) of SAT, but only 47% (14/30) of SBLB slides. When SBLB and UNS categories were combined, the discrimination from the SAT category was excellent (kappa = 0.87) with pairwise k-values of 0.94-0.97. In conclusion, adjacent field cell count methods to judge ThinPrep cellularity provide near excellent interobserver reproducibility. While we have designated both UNS and SBLB adequacy categories, criteria could easily be revised to set one threshold to separate SAT and UNS ThinPreps. Copyright 2002 Wiley-Liss, Inc.