Splanchnic vein thrombosis: clinical presentation, risk factors and treatment.

The term splanchnic vein thrombosis encompasses Budd-Chiari syndrome (BCS), extrahepatic portal vein obstruction (EHPVO), and mesenteric vein thrombosis; the simultaneous involvement of additional regions is frequent, and clinical presentations and risk factors may be shared. The annual incidence of BCS and isolated mesenteric vein thrombosis is less than one per million individuals, while the incidence of EHPVO is about four per million; autopsy studies, however, suggest higher numbers. Current advances in non-invasive vascular imaging allow for the identification of chronic or asymptomatic forms. Risk factors can be local or systemic. A local precipitating factor is rare in BCS, while it is common in patients with portal vein thrombosis. Chronic myeloproliferative neoplasms (MPN) are the leading systemic cause of splanchnic vein thrombosis, and are diagnosed in half the BCS patients and one-third of the EHPVO patients. The molecular marker JAK2 V617F is detectable in a large majority of patients with overt MPN, and up to 40% of patients without overt MPN. Inherited thrombophilia is present in at least one-third of the patients, and the factor V Leiden or the prothrombin G20210A mutations are the most common mutations found in BCS or EHPVO patients, respectively. Multiple factors are present in approximately one-third of the patients with BCS and two-thirds of the patients with portal vein thrombosis. Immediate anticoagulation with heparin is used to treat patients acutely. Upon clinical deterioration, catheter-directed thrombolysis or transjugular intrahepatic portosystemic shunt is used in conjunction with anticoagulation. Long-term oral anticoagulation with vitamin K-antagonists (VKA) is recommended in all BCS patients, and in the patients with a permanent prothrombotic state associated with an unprovoked EHPVO. In patients with an unprovoked EHPVO and no prothrombotic conditions, or in those with a provoked EHPVO, anticoagulant treatment is recommended for a minimum of 3-6 months.