Predictors of Success of Conventional ERCP for Bile Duct Stones and of Need for Single Operator Cholangioscopy

Introduction  The characteristics of difficult stones requiring cholangioscopy-assisted lithotripsy is poorly defined. We sought to determine clinicians’ perception of these characteristics and decision making in biliary endoscopy. Methods 124 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 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 angulation <135̊’. Multilevel (mixed) statistical methods with a two-level model were utilised with multilevel ordinal logistic regression. Results  Stone size and location, stricture and stone diameter:duct ratio impacted on perceived procedural difficulty p<0.01). Stone:duct ratio (<50% OR 0.22, p <0.001), stricture (OR 7.26, p<0.001) and stone location impacted on 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 <1350 predicted cholangioscopy requirement (p<0.01). Stone number did not influence procedural 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.