Objective: To start an interexchange program for quality control in cervical cytology and discuss conceptual criteria for diagnosis.
Study design: Slides were selected in the archives of the 2 institutes and included cases with unsatisfactory, negative and positive results. Sets of slides were changed between the partners every 3 months. At the end of each year a senior cytopathologist was invited to discuss the major discrepancies found in the study.
Results: A total of 1,041 cases were analyzed. Full concordance was obtained in 74.4% (774) of cases and discrepancies in 25.6% (267 cases). Full agreement was achieved in 276 (39%) of 707 cases categorized as negative. In 421 negative cases from laboratory A, this concordance represents 65.5% and 96.5% for laboratory B, which submitted 286 negative cases. The main discordance was the high number of atypical squamous cells of undetermined significance cases: 3.1% for A and 128 (33.2%) for B. Samples with discrepancies related to the quality of the material was another controversial issue: of 16 cases from laboratory A, 6 (37.5%) unsatisfactory cases were the same and 10 (62.5%) different. Laboratory B presented 20 unsatisfactory cases, and 14 (70.0%) had other diagnoses. Low grade squamous intraepithelial lesion and high grade squamous intraepithelial lesion concordance ranged from 75% to 80%, and invasive carcinoma has 4 discordances (28.5%), 3 previously screened as high grade squamous intraepithelial lesion and 1 as atypical squamous cells of undetermined significance. The kappa value obtained was 0.65, indicating substantial agreement.
Conclusion: Our results indicated that atypical squamous cells of undetermined significance diagnoses are the crucial point of controversies and concern the quality of routine diagnosis in cytopathology.