Portal vein obstruction results from thrombosis (blood clot) or narrowing of the portal vein, which brings blood to the liver from the intestines. Because the portal vein is narrowed or blocked, pressure in the portal vein increases. This increased pressure (called portal hypertension) causes the spleen to enlarge. It also results in dilated, twisted (varicose) veins in the esophagus and often in the; these can bleed profusely. Fluid accumulation in the abdomen is not common but may develop when the blockage of the portal vein is accompanied by liver congestion or damage or when large amounts of fluids are given intravenously to treat major bleeding from ruptured veins in the esophagus or stomach.

Signs and Symptoms

Most people do not have any symptoms. In some people, problems gradually develop, resulting from portal hypertension. If varicose veins develop in the esophagus or stomach, they may rupture and bleed, sometimes profusely. People then vomit blood. The blood may also pass through the digestive tract, making stools black, tarry, and foul-smelling. Another vascular complication of portal hypertension is the development of abnormal small veins and capillaries in the stomach, which may result in gastrointestinal bleeding.