Predictors of success of conventional ERCP for bile duct stones and need for single-operator cholangioscopy

Background and study aims The characteristics of difficult stones requiring cholangioscopy-assisted lithotripsy are poorly defined. We sought to determine clinician perception of these characteristics and decision-making in biliary endoscopy. Methods One hundred twenty-four delegates attending an online course were invited to assess 20 clinical stone cases. Each image was graded on a 4-point Likert for: grading of stone difficulty, confidence of clearance with conventional endoscopic retrograde cholangiopancreatography (ERCP) methods, likelihood of needing cholangioscopy-assisted lithotripsy, and confidence of clearance with one session of lithotripsy. An independent reviewer rated each case on largest stone size, stone number, presence of stricture distal to stone, size of stone relative to distal duct size, and acute common bile duct (CBD) angulation < 135°. Multilevel (mixed) statistical methods with a two-level model were utilized with multilevel ordinal logistic regression. Results Stone size and location, stricture and stone diameter:duct ratio impacted perceived procedural difficulty P < 0.01). Stone:duct ratio (< 50% odds ratio [OR] 0.22, P < 0.001), stricture (OR 7.26, P < 0.001) and stone location impacted confidence of clearance with conventional ERCP. Intrahepatic and cystic duct stones were least likely to engender confidence ( P < 0.01). The same factors plus CBD angulation < 135° predicted cholangioscopy requirement ( P < 0.01). Stone number did not influence procedure difficulty or cholangioscopy requirement. Strictures (OR 0.29, P < 0.001) and location, especially intrahepatic (OR 0.42, P < 0.001) impaired confidence in clearance with one cholangioscopy session. Conclusions Ductal anatomy, the presence of a stricture distal to a stone, cystic and intrahepatic stones and stones larger than the distal duct are considered by endoscopists to be significant predictors of requiring cholangioscopy-assisted lithotripsy.