['This study assesses the value of intraductal ultrasound (IDUS) when the findings of endoscopic retrograde cholangio-pancreatography (ERCP) are unclear.', 'IDUS was performed over a two-year period in cases of bile duct or pancreatic duct stenosis of unknown origin found during ERCP or if cholelithiasis was suspected but ERC was seemingly normal. Duct stenoses were classified,before and after IDUS, as benign or malignant ductal or malignant extraductal, the findings then being checked by clinical follow-up,histology or, if bile duct stones had been suspected, by instrumental bile duct exploration.', 'Among 1303 ERCP investigations IDUS was attempted in 125 patients (9.6%; average age 60+/-14 years; 62 females). IDUS failed in seven patients for technical reasons (failure rate 6%). IDUS took an average time of 9+/-3 min. ERCP plus IDUS provided correct classification in 52 of 60 patients with bile duct stenosis (87%), and in 14 of 16 (88%) patients with pancreatic duct stenosis.ERCP alone correctly classified duct stenosis in 54 of 76 patients(87%), but in 66 of 76 (87%) with additional IDUS. The correct demonstration or exclusion of choledocholithiasis was obtained by IDUS in 40 of 42 patients (95%). Thus IDUS changed the diagnosis made by ERCP in 28 of 118 patients (24%).'] Does [ Clinical value of intraductal ultrasonography for clarification of confusing ERCP result ]?