Haematopoietic response and bcl-2 expression in patients with acute myeloid leukaemia

In the Bethesda System for reporting cervicovaginal cytology results, 1 criterion for smear adequacy is an adequate squamous component. The accuracy of a cytologist's estimate that 10% of the slide is covered by squamous cells, the adequacy threshold, has not been determined. The percentage of the surface of a glass slide covered by squamous cells was independently estimated by 4 cytologists on 2 occasions by microscopic examination of 83 buccal smears prepared to display estimated coverage of 1% to 20% of the slide surface. The accuracy of visual estimates was compared with measurements by the TracCell System. Each observer made a third set of estimates after receiving 5 slides with known coverage. Median coverage by visual estimation ranged from 4% to 25%, but as measured by the TracCell system was 2%. Median estimated coverage was significantly different for 2 of 4 observers between first and second viewings and between all but 1 pair of observers. For all observers, it was significantly higher than the true coverage. A visual estimate of 10% coverage corresponded to a true median coverage of 3%. When provided with a physical standard, the median estimated coverage by 3 of 4 observers was not statistically different from the true coverage, and interobserver kappa values improved. Unaided visual estimation of the adequacy of squamous cell coverage is neither reproducible nor accurate. What most cytologists consider "adequate" coverage represents only 3% coverage. The availability of a physical standard dramatically increases reproducibility and accuracy.