β -thalassemia major, a chronic, inherited hematological disease,  leads to chronic anemia in the affected children. One of the options of treatment in such patients is splenectomy; However , this treatment involves risk of many complications , one of which is portal vein thrombosis which is either complete or partial obstruction and it is  a rare serious complication in thalassemia patients, especially postsplenectomy and it requires a very high index of suspicion to confirm the early diagnosis and urgent therapy to prevent fatal complications such as portal vein hypertension or bowel infarction . The risk factors include excessive adhesion to endothelial cells, low levels of Protein C and S, increased prothrombin fragment 1.2.( which is a marker of thrombin generation, especially in thalassemia intermediate patients ), exposure of external membrane of abnormal red blood cells (RBCs) to phosphatidylserine (PTS), increased circulating and aggregated of platelets , Low nitric oxide (NO)  due to hemolysis secondary to reduce the arginine level (it causes pulmonary vasoconstriction and causes pulmonary vasoconstriction and subsequently leads to chronic pulmonary thromboembolism ,  organ dysfunction and thrombophilia .

The diagnosis becomes clear with advance in the quality of X ray finding , usually associated with prolonged prothrombin time , D dimer and alkaline phosphatase are usually high. The incidence of PVT is between 1.7-9.2% . It is initially asymptomatic , symptoms appear gradually as thrombosis progress .The treatment includes, the treatment of causal factors , prevention of thrombus and achieving the patency of portal vein by regular red blood cell transfusion and antithrombotic agents .