the most common cause of portal hypertension is cirrhosis of the liver. cirrhosis results from scarring of a liver injury caused by hepatitis alcohol abuse or other causes of liver damage. in cirrhosis scar tissue blocks the flow of blood through the liver. other causes of portal hypertension include blood clots in the portal vein blockages of the veins that carry the blood from the liver to the heart and a parasitic infection called schistosomiasis. sometimes the cause is unknown.
what causes portal hypertension?