Ultrasonic cholangiography. Gray-scale B-scan evaluation of the common bile duct.

Gray-scale B-scanning permits evaluation of major portions of the bile ducts, especially those with significant dilatation. Injection of contrast material containing microscopic air bubbles through a T-tube with simultaneous ultrasonography detected multiple echoes filling in the previously echo-free area which represented the common bile duct, outlining both the duct and portions of the major tributaries. Reflections could be obtained from stones within the duct. Follow-up examinations after surgery could be used to demonstrate shrinkage of the duct. Jaundice due to extra- or intrahepatic obstruction was successfully differentiated noninvasively.