Venous thrombosis in splanchnic or atypical territory

Specialty: Hematology.

• Portal vein thrombosis
• splenic vein thrombosis
• hematological Budd-Chiari syndrome
• mesenteric thrombosis

Why it occurs

• Polycythemia vera or Essential thrombocythemia (frequently associated with the presence of the JAK2 V617F mutation, which alters the splanchnic vascular endothelium and directly activates local leukocytes and platelets)
• Paroxysmal nocturnal hemoglobinuria (clonal disease of the hematopoietic stem cell with deficiency of protective complement proteins CD55/CD59, which induces intravascular hemolysis and an extreme prothrombotic state with a predilection for suprahepatic or cerebral veins)
• Primary or secondary antiphospholipid syndrome (presence of lupus anticoagulant, anticardiolipin or anti-beta-2-glycoprotein I antibodies that induce diffuse endothelial and platelet activation)
• Congenital deficiencies of natural anticoagulants (deficiency of protein C, protein S or antithrombin III, characterized by recurrent venous thromboses in young people)
• Mutation of the prothrombin gene G20210A or Factor V Leiden.

Initial workup

Abdominal Doppler ultrasound focusing on the portal venous system, splenic, mesenteric and suprahepatic veins (initial test of choice, with high sensitivity to detect the absence of flow and intraluminal thrombi); Triphasic abdominal CT angiography or abdominal magnetic resonance imaging (to precisely delineate the extent of thrombosis, viability of the intestinal loop, and presence of portosystemic collaterals); molecular study for the JAK2 V617F mutation (even in the absence of alterations in the blood count, since it may present as an occult manifestation of a myeloproliferative neoplasm); flow cytometry in peripheral blood to analyze the expression of GPI anchoring (CD55 and CD59 on granulocytes and erythrocytes) to rule out Paroxysmal Nocturnal Hemoglobinuria; complete thrombophilia panel (lupus anticoagulant, anticardiolipin antibodies, protein C and S activity, antithrombin III, Factor V Leiden mutation).

Standard management

• Low molecular weight heparin / Enoxaparin — full anticoagulation dose at a rate of 1 mg/kg subcutaneously every 12 hours or 1.5 mg/kg every 24 hours; first choice in the acute phase due to its rapid onset of action and less interference with diagnostic tests
• Direct oral anticoagulants / Rivaroxaban or Apixaban — oral alternative for long-term maintenance if there is no severe hepatic or digestive contraindication
• Eculizumab or Ravulizumab — monoclonal antibodies directed against complement protein C5; specific and urgent indication if the thrombosis is secondary to Paroxysmal Nocturnal Hemoglobinuria, drastically reducing the prothrombotic state
• Ruxolitinib (selective JAK1/2 inhibitor, indicated in chronic phases of myeloproliferative neoplasms to reduce splenomegaly and normalize the endothelial inflammatory profile).