Ultrasonic evaluation of the common bile duct.

The efficacy of ultrasound in detecting a tumor in the head of the pancreas as a cause of obstructive jaundice has been well established. With gray scale imaging, it is possible to visualize the biliary tract including the common bile duct, and thereby to differentiate between extrahepatic (obstructive) and intrahepatic (hepatocellular and cholestatic) jaundice in many cases.