Nearly all portal vein disorders obstruct portal vein blood flow and cause portal hypertension (see Approach to the Patient With Liver Disease: Portal Hypertension). Obstruction can be

• Extrahepatic—portal vein thrombosis due to a hypercoagulable state, vessel wall lesion (eg, pylephlebitis, omphalitis), an adjacent lesion (eg, pancreatitis, tumor), or congenital atresia of the portal vein
• Intrahepatic (eg, microvascular portal vein obstruction as in schistosomiasis, primary biliary cirrhosis, sarcoidosis, noncirrhotic portal hypertension)

Portal Vein Thrombosis

Portal vein thrombosis causes portal hypertension and consequent GI bleeding from varices, usually in the lower esophagus or stomach. Diagnosis is based on ultrasonography. Treatment involves control of variceal bleeding (usually with endoscopic banding, IV octreotide, or both), prevention of recurrence using β–blockers and sometimes surgical shunts and thrombolysis for acute thrombosis.

Etiology

Common causes vary by age group (see Table 1: Vascular Disorders of the Liver: Common Causes of Portal Vein Thrombosis*).

Table 1
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Common Causes of Portal Vein Thrombosis* Age Group Cause Comments Neonates Umbilical stump infection or omphalitis (spread via the umbilical vein to the portal vein) Congenital portal vein abnormalities (less common) Congenital abnormalities of the portal vein usually accompany congenital defects elsewhere. Older children Pylephlebitis In acute appendicitis, infection enters the portal system; the vascular infection/inflammation then triggers thrombosis. Adults Surgery (eg, splenectomy) Hypercoagulable states (eg, myeloproliferative disorder, protein C or S deficiency, pregnancy) Cancer (eg, hepatocellular or pancreatic carcinoma, renal or adrenal cancers) Cirrhosis Trauma Possibly portal hypertension causing congestion and stasis *The cause is multifactorial in most cases and unknown in about one third of cases.

Symptoms and Signs

Acute portal vein thrombosis is commonly asymptomatic unless associated with another event, such as pancreatitis (the cause), or another complication, such as mesenteric venous thrombosis. Most often, clinical features—splenomegaly (especially in children) and variceal hemorrhage—develop chronically secondary to portal hypertension. Ascites is uncommon (10%) in postsinusoidal portal hypertension. Ascites may be precipitated when cirrhosis is also present or when serum albumin (and thus oncotic pressure) deceases after high-volume fluid resuscitation for a major GI bleed.

Diagnosis

• Clinical evaluation and liver function tests
• Doppler ultrasonography

Portal vein thrombosis is suspected in patients with the following:

• Manifestations of portal hypertension without cirrhosis
• Mild abnormalities in liver function or enzymes plus risk factors such as neonatal umbilical infection, childhood appendicitis, or a hypercoagulability disorder

Doppler ultrasonography is usually diagnostic, showing diminished or absent portal vein flow and sometimes the thrombus. Difficult cases may require MRI or CT with contrast. Angiography may be required to guide shunt surgery.

Treatment

• For some acute cases, thrombolysis
• Long-term anticoagulation
• Management of portal hypertension and its complications

In acute cases, thrombolysis is sometimes successful, best reserved for recent occlusion, particularly in hypercoagulable states. Anticoagulation does not lyse clots but has some value for long-term prevention in hypercoagulable states despite the risk of variceal bleeding. In neonates and children, treatment is directed at the cause (eg, omphalitis, appendicitis). Otherwise, management is directed at the portal hypertension and its complications (see Approach to the Patient With Liver Disease: Portal Hypertension); treatment can include octreotide IV (a synthetic analog of somatostatin) and endoscopic banding to control variceal bleeding and nonselective β-blockers to prevent rebleeding. These therapies have decreased the use of surgical shunts (eg, mesocaval, splenorenal), which can become occluded and have an operative mortality rate of 5 to 50%. Transjugular intrahepatic portosytemic shunting (TIPS) is not recommended. TIPS requires monitoring (including frequent angiography) to assess patency, may become blocked, and may not adequately decompress the liver.

Last full review/revision December 2007 by Eldon A. Shaffer, MD