Reliability of endoscopic ultrasound in predicting the number and size of common bile duct stones before endoscopic retrograde cholangiopancreatography

Background: Endoscopic ultrasound (EUS) is accurate for the diagnosis of choledocholithiasis; however, data are lacking regarding the prediction of stone number and size. Aims: To evaluate the concordance between EUS and endoscopic retrograde cholangiopancreatography (ERCP) in stone number and size assessment. Methods: We performed a retrospective analysis of consecutive patients undergoing ERCP due to detection of choledocholithiasis by EUS. Concordance between EUS and ERCP was defined as difference in stone diameter <30% and perfect match in stone number. Results: Among 116 patients, 25% had sludge, 37.9% had single and 37.1% had multiple stones. Overall concordance was 62.9%. Sludge was correctly assessed in 85.7%, single stone in 81.3% and multiple stones in 45.1% (P = 0.0001). EUS was accurate in 78.8% of patients who underwent both procedures in the same session, but only in 61.9% in those who underwent ERCP within 1 week. Multivariate analysis identified the single-session approach (odds ratio 2.894; P = 0.035) and multiple stones (odds ratio 0.244; P = 0.001) as independent predictors of concordance. Conclusions: Concordance between EUS and ERCP was correlated to the single session approach and inversely correlated to the presence of multiple stones. EUS may predict potentially difficult ERCP allowing to plan the best treatment strategy.