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.

Ultrasonic visualization of normal and pathological Wirsung's ducts has become quite common, especially with the newest gray scale units. Ductal images were studied in 17 cases of quiescent chronic pancreatitis. Duct dilatation could be identified in the majority. Indexing WordsWirsung's Duct Ultrasound Chronic Pancreatitis Wirsung's Duct DilatationAs ultrasonic techniques become more reliable and resolution improves, the pancreas can be displayed more consistently and outlined more sharply. The mesenteric vessels, the splenic vein (Figs. 1-3)' the splenoportal junction, and the portal vein are commonly seen on pancreatic scans ('1-6). The common bile duct can also be visualized above and inside the head of the pancreas (6). It is then logical that we should also expect t o visualize Wirsung's duct.In a preliminary report (7), we showed that Wirsung's duct could be displayed under certain conditions. In fact, as early as 1975, Burger (8) had published a transverse scan of the pancreas, displaying a longitudinal section of an enlarged Wirsung's duct. Gosink and Leopold (9) recently published several ultrasonic scans of a dilated Wirsung's duct.

Study of 135 ultrasonograms shows that it is possible to display the normal pancreas with 82% success. The pancreatic head ranges between 11 and 30/mm/in thickness, the isthmus 4-21 mm in thickness, and the corporeo-caudate area 24-32 mm in thickness. The pancreas may have a sausage, dumb-bell, or tadpole shape. Variance from these outlines and thicknesses should be considered pathological.

Some patients, even subjects with normal weight, have a fatty tissue pad located behind the xyphoid appendix between the peritoneum, the liver and the abdominal wall muscles. The wall fatty pad is encapsulated. It is sonographically transsonic, but with high-level internal echoes, and may deform the anterior face of the liver. It can be from 8 to 13 cm wide, 5 to 10 cm high and 3 to 5 cm thick. This fatty structure may be mistaken for a parietal abscess or haematoma. The sonographical exploration of the abdominal wall with short-focussed high-frequency transducers and the knowledge of this normal variance of human anatomy should avoid such pitfalls.