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

Background:  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.

Methods:  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.

Results:  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.

Conclusions:  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.