Intraoperative administration of tranexamic acid (TXA,T) reduces significantly blood loss and blood transfusion requirements during spinal posterior fusion in adolescents with scoliosis. TXA acts mainly by inhibit the plasminogen activator.

Desmopressin (DDAVP ,D) can inhibit the fibrinolytic activity by inducing the release of von Willebrand factor from the endothelial cells. But at the same time, it releases tissue-type plasminogen activator (t-PA), which may cripple its hemostatic effect.

The investigators supposed that if the investigators combine TXA with DDAVP in scoliosis correction surgery, the blood loss and the transfusion need would be reduced significantly.

Intraoperative administration of tranexamic acid (TXA,T) reduces significantly blood loss and blood transfusion requirements during spinal posterior fusion in adolescents with scoliosis. TXA acts mainly by inhibit the plasminogen activator. Desmopressin (DDAVP ,D) can inhibit the fibrinolytic activity by inducing the release of von Willebrand factor from the endothelial cells. But at the same time, it releases tissue-type plasminogen activator (t-PA), which may cripple its hemostatic effect.

The investigators designed a a randomized double-blind clinical combining TXA with DDAVP in scoliosis correction surgery to observe if the blood loss and the transfusion need would be reduced or not.

Inclusion Criteria:

• idiopathic scoliosis patients undergoing posterior scoliosis correction surgery
• American society of anesthesiologists(ASA) classification:Ⅰ-Ⅱ
• patients who agreed to participate in this study and has signed the informed consent

Exclusion Criteria:

• blood disease，such as anaemia, idiopathic thrombocytopenic purpura(ITP)
• history of bleeding or ecchymosis
• disorders of laboratory examination on platelets(PLT),prothrombin time(PT),activated partial thromboplastin Time(aPTT),Fibrinogen,D-dimers
• hypertension
• cardiac disease,such as unstable angina, myocardial infarction in recent sis months, cardiac disfunction, congenital heart disease, pulmonary heart disease
• cerebral ischemia
• administering with anticoagulants or nonsteroidal anti-inflammatory drug(NSAID)
• hepatic or renal disease or disfunction
• blood transfusion in recent one month