Reproducibility of the Bethesda system for reporting thyroid cytopathology (TBSRTC): An observational study of 100 patients

: FNAC is the most commonly used screening test to classify patients with thyroid nodules into six Bethesda categories (category I-VI) and for therapeutic decision making. The 2023 edition of TBSRTC, further simplifies these categories, using single name and describing more clear diagnostic criteria for each of the categories. The aim of this study is to investigate the interobserver reproducibility and usefulness of this classification scheme. : FNAC smears from 100 patients with thyroid nodules from october 2022 to September 2024, over a period of 2 years were analysed retrospectively, which were reviewed and reclassified by two pathologists independently according to 2023 TBSRTC. The interobserver reproducibility was statistically assessed using Cohen’s kappa. : Interobserver agreement was seen in 95 cases (95%) and disagreement was seen in 5 cases (5%). The concordance rate was 100% in the Bethesda I and Bethesda VI, 95% (76 cases) in Bethesda II, 66% (02 cases) in Bethesda III, 66% (08 cases) in Bethesda IV and 66% (02 cases) in Bethesda V. So, interobserver variation was seen among Bethesda II, III, IV and V. Overall Cohen’s kappa value showed excellent agreement. : TBSRTC should be encouraged in our country because it reduces interoberver variability. Although there is excellent interobserver agreement seen in this study, disagreements were seen in the Bethesda categories II, III, IV and V, which corroborated with the findings of the studies done elsewhere.