Lower preoperative platelet counts, postoperative thrombocytosis, wider preoperative portal/splenic vein diameter, prolonged prothrombin time (PT), periesophagogastric devascularization, and mutation of prothrombin genes and deficiency in protein C and protein S have been considered as risk factors of PVST after splenectomy [23, 29]. The gene discussed is PROS1; the disease is Thrombocytosis.