Predictors of unsuccessful mechanical lithotripsy and endoscopic clearance of large bile duct stones

Background. Mechanical lithotripsy is used to break large bile duct stones. This study investigated the predictors of unsuccessful mechanical lithotripsy. Methods: Consecutive patients with bile duct stones underwent endoscopic retrograde cholangiography, sphincterotomy, and basket removal of stones. Mechanical lithotripsy was performed for stones of large size (>15 mm diameter) that precluded extraction intact. Success was defined as complete clearance of the duct. Various predictive factors, including size and number of stones, stone impaction, serum bilirubin, presence of cholangitis, and bile duct diameter were analyzed in relation to the success or failure of lithotripsy. Results: A total of 669 patients underwent endoscopic retrograde cholangiography for suspected choledocholithiasis, which was found in 401 patients. Of the latter patients, 87 had large stones that required mechanical lithotripsy. Lithotripsy was successful in 69 (79%) patients. Impaction of the stone(s) in the bile duct was the only significant factor that predicted failure of lithotripsy and consequent failure of bile duct clearance. Other factors, including stone size, were not significant. Conclusions: Mechanical lithotripsy is successful in about 79% of patients with large bile duct stones. The only significant factor that predicts failure of mechanical lithotripsy is stone impaction in the bile duct.