Portal Hypertension

The portal vein receives blood drained from the entire intestine and from the spleen, pancreas, and gallbladder. After entering the liver, the vein divides into right and left branches and then into tiny channels that run through the liver. When blood leaves the liver, it drains back into the general circulation through the hepatic vein .

Two factors can increase blood pressure in the portal blood vessels: increased volume of blood flowing through the vessels and increased resistance to the blood flow through the liver. In Western countries, the most common cause of portal hypertension is increased resistance to blood flow caused by cirrhosis (most often due to excessive alcohol intake).

Portal hypertension leads to the development of veins (called collateral vessels) that directly connect the portal blood vessels to the general circulation, thus bypassing the liver. Because of this bypass, substances that are normally removed from the blood by the liver are able to pass into the general circulation. Collateral vessels develop at specific places, the most important of which is at the lower end of the esophagus. Here the vessels become engorged and tortuousthat is, they become esophageal varices (varicose veins in the esophagus). These engorged vessels are fragile and prone to bleeding, sometimes seriously. Other collateral vessels may develop around the navel and at the rectum.

		Esophageal Varices

Symptoms and Diagnosis

Portal hypertension often enlarges the spleen (which drains its blood supply into the portal vessels via the splenic vein). Protein-containing fluid (ascitic fluid) may leak from the surface of the liver and intestines and expand (distend) the abdominal cavity, a condition called ascites. Varicose veins in the esophagus (esophageal varices) and in the upper part of the stomach bleed easily and sometimes massively. Varicose veins in the rectum may also bleed, though this is much less common.

Doctors can usually feel an enlarged spleen through the abdominal wall. They can detect fluid in the abdomen by noting abdominal swelling and by listening for a dull sound when tapping (percussing) the abdomen. An ultrasound scan may be used to examine the blood flow in the portal blood vessels and to detect the presence of fluid in the abdomen. A computed tomography (CT) scan can also be used to look for and examine any collateral vessels. In rare cases, a needle can be inserted through the abdominal wall and into the liver or spleen to directly measure pressure in the portal system (manometry).

Treatment

To reduce the risk of bleeding from esophageal varices, a doctor may try to reduce the pressure in the portal vein. One way is to give propranolol.

Bleeding from esophageal varices is a medical emergency. Drugs such as vasopressin or octreotide may be given intravenously to constrict the bleeding veins, and blood transfusions are given to replace lost blood. An endoscopic examination is usually done to confirm that the bleeding is from varices. The veins can then be blocked off with rubber bands or with injections of a chemical given through the endoscope.

If the bleeding continues or recurs repeatedly, a surgical procedure may be done to create a bypass (called a shunt) between the portal venous system and the general (systemic) venous system. This lowers the pressure in the portal vein, because the pressure is much lower in the general venous system.

There are various types of portal-systemic shunt operations. In one type, called transjugular intrahepatic portal-systemic shunting (TIPS), an x-ray-guided needle is passed through the liver to create a shunt connecting the portal vein directly with one of the hepatic veins. Shunt operations are usually successful in stopping the bleeding but pose certain risks, such as liver (hepatic) encephalopathy. The TIPS procedure, although less dangerous than other surgical procedures involving portal-systemic shunts, may need to be repeated periodically because of narrowing of the shunt in some people.