What is the most common cause of portal hypertension?

Portal hypertension is primarily caused by increased resistance to blood flow in the portal venous system, with cirrhosis being the most prevalent underlying condition. Cirrhosis, whether due to alcoholic liver disease, chronic hepatitis, or other factors, results in structural changes to the liver that obstruct blood flow. The fibrotic tissue replaces healthy liver cells, leading to portal vein pressure elevation.

Cirrhosis accounts for the majority of cases of portal hypertension, as it can result from various chronic liver diseases, diminishing liver function and altering vascular dynamics. Other causes like hepatic vein thrombosis can also lead to portal hypertension but are significantly less common in comparison. This makes cirrhosis the foremost cause of the condition, as it is a widespread end-stage liver disease linked to many etiologies.