Portal Hypertension: Pathogenesis and Diagnosis.

Portal hypertension (PH) is an increase in the pressure gradient between portal vein and inferior vena cava. Increased resistance occurs at different levels within the portal venous system, followed by increased portal venous inflow. PH is the main driver of cirrhosis decompensation. Varices on endoscopy or portosystemic collaterals on imaging indicate PH. Although its cause is determined mostly via noninvasive tests, the gold standard to measure portal pressure in cirrhosis and determine its severity is hepatic vein catheterization with determination of the hepatic venous pressure gradient. Measuring portal pressure is essential in proof-of-concept studies of portal pressure-lowering drugs.