Portal Hypertension

Abstract

Portal hypertension is defined as increased pressure in the portal vein and/or its tributaries. The main cause of increased pressure is obstruction along the path of venous blood flow from the portal vein, through the liver, into the hepatic veins. Portal hypertension can less commonly be due to increased portal venous inflow. Portal pressure normally ranges from 6 to 8 mmHg and increases to greater than 12 mmHg in portal hypertension (can exceed 50–60 mmHg). Cirrhosis is the most common cause of portal hypertension in the United States, with the majority being due to excessive alcohol consumption. Other causes of portal hypertension include portal vein thrombosis (most common cause in children) and schistosomiasis (worldwide leading cause of pre-sinusoidal portal hypertension). Causes of portal hypertension are separated into prehepatic, intrahepatic, and posthepatic causes. Collaterals decompress the portal circulation via channels to the systemic circulation. Collaterals and varices are formed by dilation of small, preexisting venules.