Hepatic Portal Vein

Hepatic Portal Vein

The hepatic portal vein is one of the most important components of the hepatic portal system in the body that is responsible for carrying blood from the intestine to the liver. Know the structure, location, and important functions of this blood vessel in the article to come.
Did You Know?
Roughly 75% of the blood that enters the liver is through the hepatic portal vein, and the rest is through the hepatic arteries.

Knowing the functions of a liver will make it easier for you to understand the functions of the hepatic portal vein. As we know, the human liver is a reddish-brown organ in a triangular shape, located in the right upper quadrant of the abdominal cavity and rests just below the diaphragm. The liver is an exceptional organ that receives dual blood supply - one comes from the heart through hepatic artery, and the other comes from all the digestive organs through the hepatic portal vein.

According to the anatomy, the liver is connected to two blood vessels: (i) one being the hepatic artery; and (ii) the other known as hepatic portal vein. The function of the hepatic artery is to carry the oxygenated blood from the aorta, whereas the portal vein carries the deoxygenated blood from the entire gastrointestinal tract to the liver. The hepatic portal system begins in the capillaries in the gastrointestinal tract and ends in the hepatic portal vein. The hepatic portal system comprises the portal vein and its smaller tributaries.

Structure and Location

hepatic portal vein

Hepatic portal vein, often known as portal vein, is a short vein present in the abdominal cavity. It is formed by the confluence of the superior and the splenic veins. This vein is located in the right upper quadrant of the abdomen and measures about 3 inches in adults.

It originates behind the neck of the pancreas and ascends anterior to the inferior vena cava. At the right end of the porta hepatis, it divides into two branches which ramify within the liver, forming several smaller venous branches and ultimately portal venules. Hepatic portal vein, which is one of the main parts of the portal venous system in the body is a group of veins that helps in directing blood from different parts of the gastrointestinal tract, pancreas, and spleen to the liver.

Vital Functions

The vein is responsible for draining blood from the gastrointestinal tract and spleen into the liver. It receives blood from the stomach, small intestine, large intestine, pancreas, spleen, and gallbladder through the inferior mesenteric, gastric, and cystic veins.

It carries the blood received from all these parts of the body to the liver. The blood that is brought to the liver by the portal vein is cleaned by the liver and flows into the inferior vena cava through the hepatic veins.

It is then taken to the heart for systemic circulation. The blood coming from the different parts of the digestive system is fully loaded with nutrients and toxins that have been absorbed along the tract from the ingested food.

The liver detoxifies the blood by filtering it, and that is the main reason why the blood is brought to the liver by this vein. The blood can now enter the systemic circulation of the body after all the toxins have been removed.

Diseases Related to the Vein

Thrombosis: This blood vessel is prone to developing a blood clot that causes obstruction in the normal blood flow, resulting in blocking the portal vein. The blood thus backs up in the vein itself, resulting in increased pressure in all the other veins below it. It even gets overfilled in the organs, like the spleen, from which the portal vein collects blood. This condition is known as hepatic portal vein thrombosis. It gives rise to portal pressure and may result in other serious health problems.

When the portal vein gets blocked and the blood is unable to flow normally, the body attempts to bypass the blocked vein by developing several thin-walled veins or collaterals. These collaterals appear like varicosities and may appear anywhere in the abdomen, but are generally seen at the lower end of the esophagus. The symptoms of acute hepatic vein thrombosis are vague and often skipped. However, in case of chronic thrombosis, the patient suffers from vomiting of bright red blood. Fluid accumulation in the abdomen along with confusion, loss of memory, and coma may also be the symptoms of chronic vein thrombosis. There are chances of treating this condition effectively in absence of liver diseases, or liver failure. However, it can be fatal if the liver is damaged due to some other health problems.

Portal Hypertension: This condition is caused due to elevation of hepatic venous pressure within the portal venous system. The reasons could be prehepatic, intrahepatic, or posthepatic. The hepatic portal vein that comes from the stomach, intestine, spleen, and pancreas merges into the main portal vein to form tributaries that carry blood to the liver. If for any reason the vessels in the liver are blocked, then a high pressure is created which leads to the development of large size and swollen veins, which are also known as varices that occur within the stomach, esophagus, rectum, and belly button area. These varices can rupture and bleed, which leads to severe medical conditions.

Pylephlebitis: This condition is an inflammation of the hepatic portal vein or its other branches. It mainly occurs as a complication of sepsis that arises due to infections, such as appendicitis or diverticulosis.