The prolonged bleeding time in hemophilia A: comparison of two measuring technics and clinical associations.

The authors simultaneously performed the Ivy (IBT) and the Simplate I (SBT) bleeding time in 17 volunteers with classic hemophilia A to determine whether a prolonged Simplate bleeding time was indeed indicative of impaired primary hemostasis, as has been postulated recently, or whether the technic itself accounted for the observed changes. They also assessed platelet function and Factor VIII-related activities on blood drawn that day. The SBT was prolonged in 11 patients, while the IBT was consistently normal. The platelet aggregation studies and the levels of Factor VIII-related antigen (VIII R:Ag) and ristocetin cofactor (VIII R:Rc) were normal, providing no evidence of von Willebrand's disease. The patients with a prolonged SBT were all younger than 20 years of age, bled two to three times more often than those with a normal SBT, and consumed more Factor VIII concentrate. A prolonged SBT with depressed VIII:C therefore is not indicative of von Willebrand's disease but is shared by a substantial proportion of hemophiliacs, who may be a greater risk of bleeding.