Endoscopic ultrasonography in the evaluation of dilated common bile duct.

Abdominal ultrasonography (US) is the procedure of first choice in the evaluation of a dilated common bile duct (CBD). Dilated bile ducts and the level of obstruction can be reliably demonstrated with US, but the cause can be determined in only two thirds of patients. The aim of this prospective study was to assess the value of endoscopic ultrasonography (EUS) in detecting the cause of CBD dilatation in patients in whom US could not demonstrate the cause of dilation or in whom US revealed equivocal results. This 13-month study included the evaluation of 985 patients. Ninety consecutive patients found to have an enlarged CBD (diameter, > or =7 mm) of unexplained origin during US examination were included in this study. All patients were evaluated by EUS. Final diagnosis was determined by endoscopic retrograde cholangiopancreatography with or without sphincterotomy ( n = 72) and surgical exploration ( n = 17). The following diagnoses were made by EUS: choledocholithiasis in 40 patients, benign distal stricture in 8, choledochal cyst in 2, and ova of Ascaris in 1. The dilatation of CBD was found by EUS examination to be caused by a tumor in 13 cases. These included tumor of the papilla of the Vater in six patients, distal cholangiocarcinoma in five, and pancreatic head cancer in two. Endoscopic ultrasonography provided an accurate explanation for CBD dilatation in 70 of the 76 patients (92%). We conclude that the diagnostic strategy for cholestasis should include US as a first choice. When the diagnosis of biliary obstruction remains probable, EUS should be carried out. Endoscopic retrograde cholangiopancreatography with sphincterotomy should be reserved for therapeutic use rather than diagnostic.