F5 and paroxysmal nocturnal hemoglobinuria: Hypercoagulation conditions as systemic lupus erythematosus, antiphospholipid syndrome, presence of factor V Leiden, paroxysmal nocturnal haemoglobinuria, hyperhomocysteinemia, protein C and S deficiency, and heparin induced thrombocytopenia are all reported as risk factors for OVT [6, 8].