Ultrasound in obstructive jaundice: prospective evaluation of site and cause.

A prospective study of the ability of ultrasound to accurately determine the site and etiology of biliary obstruction in 62 patients is reported. The site of obstruction was predicted in 27% of the patients, but was indeterminate in 73% because of the inability to visualize the complete biliary tract. The cause of obstruction was correctly predicted in 23% of the patients and was indeterminate in 76%. While sonography is an excellent screening method for distinguishing dilated ducts from nondilated ducts, the authors believe that direct cholangiography, or possibly computed tomography, is necessary if stringent criteria are applied to the determination of the site and cause of biliary obstruction.