Ultrasonic study of venous patterns in the right hypochondrium: an anatomical approach to differential diagnosis of obstructive jaundice.

Through real time ultrasonography, it is possible to display the splenic vein, the superior mesenteric vein, the vena porta, and the intrahepatic portal and systemic veins. In jaundice, it is of the utmost importance to carefully identify the vena porta before making a diagnosis of common bile duct enlargement. It is also necessary, when confronted with a pattern of apparently enlarged intrahepatic ducts, to conduct a thorough study of possible confluences of the ducts with the vena porta or vena cava to be certain that the ducts are not part of the portal or systemic venous network. Without such differentiation, portal enlargement caused by portal hypertension, systemic venous enlargement caused by cardiac insufficiency, or even nonpathological wide veins may lead to an erroneous diagnosis of obstructive jaundice.