Anatomy and etiology of extrahepatic portal vein obstruction in children leading to bleeding esophageal varices.

Background: The cause of extrahepatic portal vein obstruction in childhood is unknown. We investigated the anatomical features of extra hepatic portal vein obstruction to clarify its cause.

Study Design: We studied portal venous anatomy in 10 patients with extrahepatic portal vein obstruction without hepatic disturbances ranging in age from 1 to 7 years (mean age, 4.2 years) using ultrasonography, portal venography, cholangio-computed tomography, and magnetic resonance imaging.

Results: The extrahepatic portal vein was not obliterated, but it crossed over the common bile duct from the left to the right side at the cranial level of the pancreas and ran in a cranial direction along the right side of the common bile duct or coiled itself around the bile duct. Thus, the extrahepatic portal vein formed a tortuous eta-shape.

Conclusions: The portal vein was not obstructed in patients with extrahepatic portal vein obstruction but formed a characteristic eta-shape by coiling itself around the common bile duct, suggesting that extrahepatic portal vein obstruction has an embryological cause.