Abnormal biliary tract morphology Portosystemic collateral veins 2016-12-03T22:24:40Z Presence of biliary veins that serve as a collateral channel to the systemic circulation Venous blood returning from the small intestine, stomach, pancreas and spleen converges into the portal vein. The terminal branches of the hepatic portal vein and hepatic artery empty together and mix as they enter sinusoids in the liver. Conditions such as liver cirrhosis, in which scar tissue partially blocks the normal flow of blood, may increases the pressure in the portal vein (portal hypertension).When blood flow through a vessel or a vascular bed is obstructed due to occlusion, collateral pathways open up as blood bypasses the occlusion or obstruction, and this can lead to portosystemic collateral veins in the case of cirrhosis and some other hepatobiliary diseases. Collateral biliary circulation Collateral biliary veins