The value of Cholangioscopy-guided Bite-on-Bite (-on Bite) biopsies in Indeterminate Biliary Duct Strictures

Background and study aims Digital single-operator cholangioscopy (d-SOC) has improved the diagnostic accuracy of indeterminate biliary duct strictures (IBDS) through targeted intra-ductal biopsy sampling. However, the optimal biopsy technique remains uncertain. Patients and methods: This international, multicenter, prospective interventional study (November 2020–August 2022) included IBDS patients undergoing d-SOC. 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 on pathology outcomes and one-year clinical follow-up. Primary outcome was the accuracy of both biopsy techniques. Results Eighty-nine patients were included, of which 52 had hilar and 37 distal strictures. Technical success rates for single biopsies and BBB were 82/89 (92.1%) and 78/89 (87.6%), respectively. Malignancy was confirmed in 31/82 (37.8%) and 29/78 (37.2%) cases in single biopsies and BBB, respectively. Among 76 cases in whom both techniques were successful, pathology results were discordant in three (3.9%) cases, primarily due to under staging by BBB. Among 82 patients with complete follow-up, malignancy was confirmed in 51 (62.2%) patients. 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 intra-ductal tissue acquisition at a prior ERCP. The number of BBB 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.