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Hepatic Portal Veins

Here we will learn the veins that constitute the hepatic portal system; be aware that these patterns are highly variable.

Overview

The hepatic portal system transports blood from the stomach, spleen, pancreas, and small and large intestines to the liver for filtration. This distinct circulatory pathway exists to allow the liver to metabolize nutrients and toxins from blood that leaves the digestive organs.

Don’t confuse the hepatic portal veins with the hepatic veins, which transport blood away from the liver.

Chair Schematic of the portal system

The hepatic portal vein, which carries blood to the liver, forms the "back" of the chair.
Two major tributaries:

The splenic vein is the seat of the chair. The superior mesenteric vein is the back leg of the chair. The inferior mesenteric vein is the front leg of the chair; it drains into the splenic vein. This simplified imagery and nomenclature clues will help you trace blood to and from the liver. “Hepatic” refers to the liver, “mesenteric” refers to the double-layered membranous fold that secures the intestines, and “splenic” refers to the spleen.

Hepatic Portal System - Main Vessels

We show the liver and gallbladder, the stomach, small intestine, and large intestine; we’ve cut out part of the transverse colon to show vessels that run deep to it. To the left of the stomach, draw the spleen.

Hepatic portal vein and major tributaries of the portal system:

The splenic, inferior mesenteric, and superior mesenteric veins.

Notice that the splenic vein runs deep to the stomach.

Again, these are the major veins that deliver blood from the digestive organs to the liver for filtration; on the superior surface of the liver, show the inferior vena cava, which drains blood from the extensive hepatic veins and carries the filtered blood to the heart to join systemic circulation.

Hepatic Portal System - Details

Now we’ll fill in the smaller tributaries of the hepatic portal system.

Hepatic Portal Vein - Direct Tributaries

Right and left gastric veins anastomose along the lesser curvature of the stomach; they drain blood from the stomach and esophagus. The left gastric vein occasionally drains into the splenic vein, instead.

The cystic vein drains blood from the gallbladder.

The superior pancreaticoduodenal vein drains blood from the pancreas and duodenum. This vein may take a less direct route through the gastroduodenal or right gastro-omental vein.

Splenic Vein Tributaries

In addition to draining the inferior mesenteric vein, ithe splenic also receives blood from the:

Short gastric veins
Left gastro-omental vein (aka gastroepiploic vein)
Pancreatic veins (which we’ve omitted for simplicity).

Thus, the splenic vein drains the spleen and parts of the pancreas, stomach, and colon.

Inferior Mesenteric Vein Tributaries

The IMV drains blood from the distal colon and rectum via:

Left colic vein
Sigmoid vein
Superior rectal veins

Superior Mesenteric Vein Tributaries

The SMV receives blood from the distal stomach, small intestine, proximal colon, and greater omentum via the:

Right gastro-omental vein, which drains blood from the greater curvature of the stomach.
Intestinal (jejunal and ileal) vein
Ileocolic vein
Right vein
Middle vein
Inferior pancreaticoduodenal vein (not present in our diagram)

The intestinal veins form extensive anastomotic loops that drain straight veins that travel through the mesentery from the small intestines.

Portal Hypertension

Portal hypertension occurs when the hepatic portal vein becomes blocked. As a result, portal blood pressure increases and varices can form; these thin-walled, engorged vessels are susceptible to trauma, and rupture can lead to fatal hemorrhaging.

Cirrhosis is an important cause of portal hypertension; this is a condition in which scar tissue replaces healthy liver tissue.

Hepatic Portal Veins

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