Portal hypertension is elevated blood pressure in the portal vein, the major vein that carries blood to the liver.
Portal hypertension is most often caused by cirrhosis, or scarring of the liver, which prevents adequate blood flow through the liver. With blood flow impaired by scar tissue, the increased pressure causes large veins (varices) to develop in the stomach and esophagus. These are fragile and can bleed easily. Acute bleeding from portal hypertension requires immediate medical attention.