Coagulation Profile of Patients with Adolescent Idiopathic Scoliosis Undergoing Posterior Spinal Fusion.

BACKGROUND: Blood loss and transfusion requirements during posterior spinal fusion for adolescent idiopathic scoliosis remain a concern. The mechanism of bleeding in these patients is poorly characterized. Thromboelastography is a comprehensive test of a patient's coagulation system commonly used in cardiac surgical procedures. It has not been well studied for use in patients with adolescent idiopathic scoliosis.

METHODS: A prospective, observational study of the coagulation profile of patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion is presented. Healthy patients with adolescent idiopathic scoliosis without a bleeding abnormality were analyzed during posterior spinal fusion. Standard coagulation laboratory and thromboelastogram measures were obtained at the time of the incision and at 1-hour intervals during the surgical procedure. Laboratory values were analyzed in relation to outcomes such as bleeding, transfusion, and a fibrinolysis score.

RESULTS: Fifty-eight patients were observed. Eighty-one percent of patients were female, the mean age was 13.5 years, a mean of 11.1 levels were fused, the median estimated blood loss was 645 mL, and 47% of patients received blood products. Overall, laboratory values remained stable throughout the surgical procedure. Mild increases in prothrombin time and partial thromboplastin time were observed, and platelets remained stable. From thromboelastogram analysis, an acceleration of clot formation (decreased reaction time) and a slight increase in clot lysis (increased lysis percentage at 30 minutes) were observed. A fibrinolysis score compiled from the presence of fibrin degradation products, the presence of D-dimers, and increased prothrombin time rose steadily over surgical time. The fibrinolysis score was predictive of both transfusion and greater estimated blood loss per level.

CONCLUSIONS: The stress of posterior spinal fusion induces a hypercoagulable state in patients with adolescent idiopathic scoliosis. Over the first 2 hours of a surgical procedure, varying degrees of fibrinolysis develop. Platelets and coagulation factors are not depleted. Our data support the use of antifibrinolytic therapy for patients with adolescent idiopathic scoliosis.