Ascites may be present early on, but often resolves. Hematemesis from varices is the most common problem, but portal encephalopathy or features of hypersplenism may also occur. Extraheptic portal venous obstruction is seen most commonly in children, where it was once believed to be a complication of umbilical sepsis. This view has been questioned since a history of omphalitis and intra-abdominal sepsis has been documented in relatively few patients, and there is a seemingly higher than expected incidence of a variety of congenital abnormalities. The process can also be seen in adults, where it may complicate sepsis or pylephlebitis.
Infection remains the overall most commonly identified precipitating factor at all ages.
Abdominal trauma or surgical injury are documented causes of such obstruction, as is invasion of the portal venous system in neoplastic processes. The thrombotic and gynecologic disorders associated with Budd-Chiari syndrome have also been seen in the setting of portal venous obstruction, although the portal venous system is much less frequently involved than the hepatic venous system. The main clinical problem is to clearly distinguish patients with this condition from those whose portal hypertension is related to parenchymal liver disease. Unfortunately, cirrhosis of many etiologies may itself be complicated by a secondary extrahepatic portal vein thrombosis. Sinusoidal Dilatation Most commonly significant dilatation of the sinusoids is due to hemodynamic failure or to venous outflow obstruction.