Portal vein is opened longitudinally.
The lumen is filled with occluding fresh thrombus. This causes portal hypertension and splenomegaly but frequently the liver remains intact due to its dual circulation. Intraabdominal Infection and hepatocellular carcinoma are the main causes. Extrahepatic causes include occlusion by enlargement of hilar lymph nodes, inflammation of the portal vein due to ascending pylephlebitis secondary to infection in the appendix or colon, splenic vein thrombosis secondary to pancreatitis or secondary to surgical procedures on the abdomen. Intrahepatic causes are cirrhosis of the liver or invasion of the portal vein by primary or secondary carcinomas of the liver.