A portal venous pressure of 30 mm. Hg (elevated) and a hepatic venous wedge pressure of 5 mm. Hg (normal) may be associated with which of the following causes of portal hypertension?

A. Portal vein thrombosis.

C. Schistosomiasis.

DISCUSSION: Pressure measured by wedging a catheter into a hepatic vein (hepatic venous wedge pressure) closely correlates with directly measured portal venous pressure in patients with portal hypertension when the site of elevated resistance is at the sinusoidal or postsinusoidal level. Such is the case in alcoholic cirrhosis and alcoholic hepatitis. When the site of increased resistance is at the presinusoidal level, either within (schistosomiasis) or outside (portal vein thrombosis) the liver, the hepatic venous wedge pressure is normal despite markedly elevated portal vein pressure. Although schistosomiasis is one of the more frequent causes of portal hypertension worldwide, in North America presinusoidal portal hypertension is considerably less common than alcoholic liver disease. A normal hepatic venous wedge pressure in a patient who has bled from varices should lead one to suspect a presinusoidal cause. A specific diagnosis can often be made by visceral angiography or liver biopsy.