Detection of Residual Bile Duct Stones by Cholangioscopy After Negative ERCP Cholangiography and Interobserver Agreement: A Self-Controlled Study

Common bile duct stones (CBDS) are a common biliary disorder, and endoscopic retrograde cholangiopancreatography (ERCP) is currently the primary minimally invasive approach for their diagnosis and treatment. Complete duct clearance is generally assessed by cholangiography after stone extraction. However, conventional cholangiography may fail to detect residual stones because of air-bubble artifacts, small stone size, biliary sludge, mucosal folds, or impacted stones. Previous studies have demonstrated that occult residual stones may still be identified by direct cholangioscopy even after cholangiography indicates complete duct clearance, highlighting the limitations of conventional cholangiography. Residual stones may increase the risk of post-procedural cholangitis, recurrent biliary symptoms, recurrent CBDS, and the need for repeat ERCP. Cholangioscopy enables direct visualization of the bile duct lumen and may facilitate the detection of small stones, stone fragments, and impacted stones that are difficult to identify by cholangiography. However, prospective evidence regarding the incremental diagnostic yield of cholangioscopy after negative ERCP cholangiography remains limited. Moreover, visual interpretation during cholangioscopy may be influenced by operator experience, and evidence regarding interobserver and intraobserver agreement remains insufficient. Therefore, this prospective study aims to evaluate the additional diagnostic value of cholangioscopy for detecting stones missed by ERCP cholangiography and to assess the reproducibility of cholangioscopic visual interpretation. The findings may provide clinical evidence for optimizing the assessment of complete bile duct clearance, standardizing the use of cholangioscopy, and reducing adverse outcomes associated with residual bile duct stones.