What Causes Hepatic Vein Thrombosis?
The vascular liver disorders occur due to occlusion of blood vessels involved and are usually rare. The lesions can be classified into pre-hepatic, hepatic and post-hepatic lesions. Portal vein thrombosis is a pre-hepatic lesion, whereas, cardiac hepatopathy is an example of post-hepatic lesion. The hepatic lesions are further subdivided into pre-sinusoidal; e.g. obliterative portal venopathy, sinusoidal; e.g. sinusoidal obstruction syndrome and post-sinusoidal lesions; e.g. being Budd-Chiari syndrome. Splanchnic vein thrombosis is used to describe the combination of Budd-Chiari syndrome, portal vein thrombosis, mesenteric vein thrombosis and/or splenic vein thrombosis.
Hepatic vein thrombosis, also known as Budd-Chiari syndrome, is thrombus (blood clot) formation in the main hepatic vein. It is the obstruction of the hepatic venous outflow including the small hepatic veins to the entire hepatic and supra-hepatic inferior vena cava. Hepatic vein thrombosis occurs in 1 out of 100,000 people and commonly occurs in females more than in males.
What Causes Hepatic Vein Thrombosis?
The etiology of hepatic vein thrombosis can be roughly divided into primary and secondary etiology, although about 30 to 50% of the cases of hepatic vein thrombosis are idiopathic, i.e. they do not have any identifiable cause. Primary hepatic vein thrombosis occurs due to obstruction of intra-luminal lesion such as thrombosis and/or endophlebitis. The main etiological factor in primary hepatic vein thrombosis is myeloproliferative disorder that is present in about 40 to 50% of individuals. Secondary hepatic vein thrombosis occurs due to extra luminal compression by outside structures such as due to cysts, abscess or tumor. Other causes of hepatic vein thrombosis are usually inherited or acquired thrombophilia.
In the congenital hepatic vein thrombosis, an individual is born with deformity of hepatic vein and thus could lead to the disorder and presents in childhood.
Thrombosis could occur due to blood clotting disorders such as deficiency of protein C, protein S and/or phospholipid syndrome.
Hepatic vein thrombosis could also occur due to drugs such as oral contraceptives, immunosuppressants and/or pyrrolizidine alkaloids (found in certain herbs such as comfrey and borage).
It can also occur due to an injury/trauma to hepatic veins that might lead to blood clot in hepatic vein.
Excessive and prolonged exposure of hepatic veins to radiation might also lead to hepatic vein thrombosis such as radiation therapy for cancers.
Hepatic vein thrombosis can also be caused due to certain tumors that might compress hepatic vein leading to blood clot formation in hepatic vein. The cancers that are usually associated with it are liver, kidney, bile duct, pancreas and adrenal cancers.
Certain medical disorders such as thrombophilia, sickle cell anemia, Behcet’s syndrome, and paroxysmal nocturnal hemoglobinuria also increase the tendency of blood to thicken, thus increasing the chance of blood clot formation in hepatic vein.
Hepatic vein thrombosis can also be seen in infections such as tuberculosis as well as in pregnant women.
Symptoms of Hepatic Vein Thrombosis
Hepatic vein thrombosis has a classical triad of hepatomegaly (enlargement of liver), ascites (fluid accumulation in the abdomen) and abdominal pain (present mostly in the upper right quadrant of the abdomen). It can range from being asymptomatic to presenting with liver failure. Other symptoms include nausea, vomiting, hematemesis, sudden epigastric pain, splenomegaly, abdominal collateral vein distention, jaundice, esophageal varices and tendency to bleed, lower extremity swelling, portal hypertension, unexplained weight loss and/or encephalopathy.
Diagnosis And Treatment
The diagnosis is done based on medical history, physical exam, and blood tests including liver function tests. The definitive diagnosis is done using imaging such as ultrasound, CT scan, an MRI and on occasions a liver biopsy is indicated.
The treatment of hepatic vein thrombosis includes identification of cause and management of symptoms with the aim of reducing fluid accumulation in the abdomen and legs with the help of water pills. Anticoagulation therapy, thrombolysis, angioplasty, transjugular intrahepatic portosystemic shunt (TIPS), surgical shunts and liver transplant are all part of management of hepatic vein thrombosis. The advances in management have improved the outcome in hepatic vein thrombosis with a 90% five-year survival rate.
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