The value of cholangioscopy-guided bite-on-bite (-on bite) biopsies in indeterminate biliary duct strictures

Digital single-operator cholangioscopy (dSOC) has improved the diagnostic accuracy of indeterminate biliary duct strictures (IBDS) through targeted intraductal biopsy sampling. However, the optimal biopsy technique remains uncertain.

This international, multicenter, prospective interventional study (November 2020-August 2022) included patients with IBDS undergoing dSOC. Stricture sampling involved obtaining at least four single biopsies and at least one bite-on-bite biopsy (BBB) in all patients. Definitive diagnosis was established by pathology outcomes and 1-year clinical follow-up. The primary outcome was the accuracy of both biopsy techniques.

89 patients were included, with 76 hilar strictures and 13 distal strictures. Technical success for obtaining adequate tissue samples was 82/89 (92.1 %) for single biopsies and 78/89 (87.6 %) for BBB. Malignancy was confirmed in 31/82 (37.8 %) and 29/78 (37.2 %) cases in single biopsies and BBB, respectively. Among 76 patients in whom both techniques were successful, pathology results were discordant in three cases (3.9 %), primarily due to understaging by BBB. Among 82 patients with complete follow-up, malignancy was confirmed in 51 (62.2 %). Sensitivity, specificity, and accuracy for malignancy or high grade dysplasia were 66.0 %, 100 %, and 78.8 % for single biopsies, and 63.8 %, 100 %, and 77.6 % for BBB, respectively. Sensitivity and accuracy were significantly decreased after stent placement or intraductal tissue acquisition during prior ERCP. The number of BBBs did not impact sensitivity or accuracy.

BBB did not outperform at least four single biopsies for IBDS. Prior manipulation of IBDS, through stent placement or prior tissue acquisition, was associated with a decreased diagnostic yield.