Raised blood pressure in the PORTAL VEIN entering the LIVER. This results in increased pressure in the veins of the oesophagus and upper stomach; these grow in size to form varices – dilated tortuous veins. Sometimes these varices rupture, causing bleeding into the oesophagus. The raised pressure also causes fluid to collect in the abdomen and form ASCITES. The commonest reason for portal hypertension is cirrhosis (fibrosis) of the liver (see LIVER, DISEASES OF). THROMBOSIS in the portal vein may also be a cause. Treatment requires the cause to be addressed, but bleeding from ruptured vessels may be stopped by injecting a sclerosant or hardening solution into and around the veins. Sometimes a surgical shunt may be done to divert blood from the portal vein to another blood vessel.