What is the portal vein and what is its main function?

The portal vein is a key venous structure that transports nutrient-rich blood from the gastrointestinal tract, pancreas, spleen, and gallbladder to the liver for metabolism and detoxification. It supplies about 80% of the liver's blood flow and lacks valves in its system.

Where does the portal vein form and what is its course?

It forms behind the neck of the pancreas at the L2 vertebra by the union of the splenic vein and superior mesenteric vein. It ascends behind the duodenum, enters the lesser omentum, and divides into right and left branches at the porta hepatis.

What are the main tributaries of the portal vein?

The primary tributaries include the splenic vein and superior mesenteric vein (formative), inferior mesenteric vein (usually joins splenic vein), left and right gastric veins, cystic vein, and paraumbilical veins.

What are portocaval anastomoses and why are they important?

Portocaval anastomoses are connections between the portal and systemic venous systems that become significant in portal hypertension. Key sites include the esophagus, umbilicus, and anal canal, leading to conditions like varices and hemorrhoids.

What clinical conditions are associated with the portal vein?

The main condition is portal hypertension, often caused by cirrhosis or thrombosis, leading to splenomegaly, ascites, esophageal varices (risk of hematemesis), caput medusae, and hemorrhoids.

How does the portal vein relate to the liver's blood supply?

The portal vein provides about 80% of the liver's blood flow, carrying nutrient-rich blood. It ends in hepatic sinusoids, where it mixes with blood from the hepatic artery before draining into the inferior vena cava via hepatic veins.

Portal Vein – Formation, Tributaries & Portocaval Sites