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Anatomy · Heart & blood vessels

Hepatic portal vein

A vein between two capillary beds

Abdomen · portal circulation

A short, wide vein about 8 cm long, formed behind the neck of the pancreas by the union of the superior mesenteric and splenic veins. It carries nutrient-rich blood from the gut, spleen and pancreas to the liver, where it breaks up into sinusoids. This makes it a portal vein: blood passes from capillaries in the gut, through a vein, into a second set of capillaries in the liver before returning to the heart.

How to spot them

  • ▸Formed behind the neck of the pancreas, at about L1–L2, where the superior mesenteric vein meets the splenic vein
  • ▸Ascends in the free edge of the lesser omentum (hepatoduodenal ligament) with the hepatic artery and bile duct in front
  • ▸Divides at the porta hepatis into right and left branches
  • ▸Has no valves

What to know

A vein that begins and ends in capillaries: gut capillaries drain into it, and it divides into sinusoids in the liver

Hepatic portal vein — a true portal system.

Formed behind the neck of the pancreas by the union of the superior mesenteric and splenic veins

Hepatic portal vein.

Runs up in the free edge of the lesser omentum, behind the bile duct and hepatic artery

Hepatic portal vein — the portal triad in the hepatoduodenal ligament.

Supplies about three-quarters of the blood reaching the liver, with the hepatic artery supplying the rest

Hepatic portal vein — roughly 75% of liver blood flow.

A high pressure in it opens up anastomoses that produce oesophageal varices and a 'head of Medusa' around the umbilicus

Hepatic portal vein — portal hypertension, e.g. from cirrhosis.

Compressing it between finger and thumb at the free edge of the lesser omentum controls liver bleeding during surgery

Hepatic portal vein — the Pringle manoeuvre.

Carries blood laden with absorbed nutrients and drugs, which the liver processes before it reaches the general circulation

Hepatic portal vein — first-pass metabolism.

Key ideas

  • Portosystemic anastomoses: where portal and systemic veins meet (lower oesophagus, anorectal junction, umbilicus, retroperitoneum), raised portal pressure diverts blood via these and causes varices, haemorrhoids and caput medusae.
  • The inferior mesenteric vein usually drains into the splenic vein, sometimes directly into the superior mesenteric vein or the confluence.

Quick-fire facts

  • •Approximately 8 cm long, formed at the level of L1–L2 behind the neck of the pancreas.
  • •Tributaries include the superior mesenteric, splenic, inferior mesenteric, left and right gastric and cystic veins.
  • •Carries about 75% of the liver's blood flow, but only roughly half to two-thirds of its oxygen supply; the hepatic artery brings the rest.
  • •Has no valves, so raised pressure is transmitted back to the gut, spleen and anastomoses.
  • •Portal hypertension is most often due to cirrhosis; it causes splenomegaly, ascites and varices.
  • •The Pringle manoeuvre, described by James Hogarth Pringle in 1908, clamps the hepatoduodenal ligament to control liver bleeding.
  • •The portal triad in the liver's lobules consists of a branch of the portal vein, hepatic artery and bile duct.
  • •Blood leaves the liver by the hepatic veins into the inferior vena cava.

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Sources