Clinical approach to splanchnic vein thrombosis: risk factors and treatment.

Splanchnic vein thrombosis (SVT) is an unusual manifestation of venous thromboembolism which involves one or more abdominal veins (portal, splenic, mesenteric and supra-hepatic veins). SVT may be associated with different underlying disorders, either local (abdominal cancer, liver cirrhosis, intra-abdominal inflammation or surgery) or systemic (hormonal treatment, thrombophilic conditions). In the last decades, myeloproliferative neoplasm (MPN) emerged as the leading systemic cause of SVT. JAK2 mutation, even in the absence of known MPN, showed a strong association with the development of SVT, and SVT was suggested to be the first clinical manifestation of MPN. Recently, an association between SVT, in particular supra-hepatic vein thrombosis, and paroxysmal nocturnal hemoglobinuria has also been reported. SVT occurs with heterogeneous clinical presentations, ranging from incidentally detected events to extensive thrombosis associated with overt gastrointestinal bleeding, thus representing a clinical challenge for treatment decisions. In the absence of major contraindications, anticoagulant therapy is generally recommended for all patients presenting with acute symptomatic SVT, but there is no consensus about the use of anticoagulant drugs in chronic or incidentally detected SVT. High quality evidence on the acute and long-term management is substantially lacking and the risk to benefit-ratio of anticoagulant therapy in SVT still needs to be better assessed.