Bên ngoài hệ thống nâng lên trong DIC, sử dụng warfarin, suy gan, myelofibrosis, thiếu hụt vitamin K, chất béo kém hấp thu, lưu hành các thuốc chống đông máu, thiếu hụt yếu tố nâng lên trong sự thiếu hụt yếu tố, lưu hành các thuốc chống đông máu, heparin sử dụng liên quan đến số lượng tiểu cầu | HIGH-YIELD FACTS TABLE 15-5. Coagulation tests. Test Purpose PT INR Extrinsic system Elevated in DIC warfarin use liver failure myelofibrosis vitamin K deficiency fat malabsorption circulating anticoagulants factor deficiencies aPTT Intrinsic Elevated in factor deficiencies circulating anticoagulants heparin use Bleeding time Surgical Related to platelet count If lengthened and platelet count is normal consider qualitative platelet defect Platelet count Related to bleeding time 100 000 mm3 mild prolongation of bleeding time 50 000 easy bruising 20 000 increased incidence of spontaneous bleeding Platelet aggregation Qualitative May be abnormal even with normal platelet count qualitative platelet disorders Glanzman s thrombasthenia von Willebrand factor deficiency Fibrin degradation products Fibrin activation Elevated in DIC trauma inflammatory disease D-dimer Intravascular fibrinolysis Present in most individuals especially with cancer trauma Sensitive for active clotting but not specific Assays for specific factors Quantitative Hemophilia A VIII hemophilia B IX von Willebrand factor deficiency VIII vWF PT prothrombin time INR international normalized ratio aPTT activated partial thromboplastin time. - Typical Scenario - A child presents with epistaxis prolonged bleeding time and a normal platelet count. Think von Willebrand s disease. von Willebrand Disease Definition Most common hereditary bleeding disorder. Etiology Autosomal dominant chromosome 12 Deficiency of factor VIII-R Pathophysiology Defective platelet function due to decrease in level or function of von Willebrand cofactor Three types Type I low levels of von Willebrand factor vWF and factor VIII Type II abnormal vWF Type III may have total absence of vWF and 10 factor VIII levels Signs and Symptoms Easy bruising Heavy or prolonged menstruation Frequent or prolonged epistaxis Prolonged bleeding after injury surgery circumcision or invasive dental procedures 254 Diagnosis Increased aPTT and bleeding time
