Section 10. Liver and Gallbladder Disorders

Chapter 138. Blood Vessel Disorders of the Liver

Topics: Introduction | Abnormalities of the Hepatic Artery | Veno-occlusive Disease | Budd-Chiari Syndrome | Portal Vein Thrombosis | Blood Vessel Disorders Resulting From Other Diseases

Portal Vein Thrombosis

Portal vein thrombosis is a blockage (by a blood clot) of the portal vein, which brings blood to the liver.

Portal vein thrombosis can be caused by any blood clotting disorder or by any condition that backs up blood in the portal vein, such as Budd-Chiari syndrome, chronic heart failure (see Section 3, Chapter 25), or chronic constrictive pericarditis (see Section 3, Chapter 30). It may also be caused by cirrhosis (severe scarring of the liver) or by cancer of the liver, pancreas, or stomach. Or it may be caused by inflammation of the bile ducts (cholangitis), inflammation of the pancreas (pancreatitis), or a liver abscess (a pus-filled pocket of infection). In newborns, portal vein thrombosis may result from an infection of the navel. Portal vein thrombosis can occur in pregnant women, especially in those with eclampsia (see Section 22, Chapter 258). However, in more than half of the people with portal vein thrombosis, the cause cannot be found.

Symptoms and Diagnosis

Blockage of the portal vein raises the pressure in the portal vein and in the other veins that drain into it (portal hypertension). This higher pressure may cause dilated, twisted (varicose) veins in the esophagus (esophageal varices) to form, which may rupture and bleed, sometimes massively. The bleeding results in vomiting of blood. Such bleeding is often the first symptom of portal vein thrombosis. The spleen typically enlarges, especially in children. A doctor can feel an enlarged spleen, which may be tender.

In about one third of people with portal vein thrombosis, blockage of the portal vein develops slowly, allowing other blood channels (collateral channels) to become established around the block. Rarely, the portal vein reopens. Even with such reopening, high pressure in the portal vein may persist.

A doctor suspects portal vein thrombosis based on the findings during a physical examination: primarily, sudden bleeding in the upper digestive tract and an enlarged spleen. Ultrasound, CT, or MRI can be helpful. To confirm the diagnosis, a doctor may perform a liver biopsy (see Section 10, Chapter 134), in which a small piece of liver tissue is removed with a needle and examined under a microscope. If the person has high pressure in the portal vein and the biopsy reveals that the cells are normal, portal vein thrombosis is a possible culprit. Ultrasound or computed tomography (CT) scans may show the blockage. The diagnosis is confirmed by angiography--an x-ray technique that creates images of the veins after a radiopaque dye (a dye visible on x-rays) is injected into the portal vein--or by magnetic resonance imaging (MRI).

Treatment

Treatment is aimed at reducing the pressure in the portal vein and preventing bleeding of esophageal varices.

Surgery may be performed to create a connection (shunt) between the portal vein and the inferior vena cava, causing blood flow to bypass the liver, thereby reducing the pressure in the portal vein. If cirrhosis is present or liver function is impaired, bypass surgery increases the risk of liver encephalopathy (brain damage from liver disease (see Section 10, Chapter 135)). Sometimes, instead of surgery, a radiologist can connect the hepatic venous system to the portal vein by passing a needle through the skin and directly into the liver; guide wires and catheters are then inserted through the needle and used to create a shunt.

In some people, liver transplantation may be the most effective treatment, depending on the underlying cause and on the condition of the person (see Section 16, Chapter 187).

A doctor may try to close the esophageal varices by applying rubber bands to them (ligation) or by injecting them with irritating chemicals (sclerotherapy) given through an endoscope (a flexible viewing tube with surgical attachments).