The patient's elevated aPTT, normal PT, and abnormal bleeding time are consistent with her von Willebrand disease (vWD). von Willebrand factor (vWF) is an impoant stimulus for platelet aggregation at the site of tissue injury and a major carrier protein for circulating factor VIII. There are three major groups of vWD. Type I, inherited as an autosomal dominant trait, has decreased levels of vWF. Type II is variably inherited and has qualitative defects in vWF. Type III is an autosomal recessive severe bleeding disorder with absent levels of vWF. Patients with vWD present with mucosal bleeding, petechiae, epistaxis, and menorrhagia. vWD produces a depressed ristocetin cofactor assay (which measures the effectiveness of vWF in agglutinating platelets when stimulated with the antibiotic ristocetin). These patients do not generally require treatment unless they need surgery or are severely injured. DDAVP, a synthetic analogue of vasopressin, activates receptors that result in release of vWF from storage sites and causes shoening in the bleeding time in patients with type I vWD and some patients with type II vWD. vWF prevents inactivation of factor VIII; administration of DDAVP results in normalization of factor VIII activities. Transfusion of cryoprecipitate provides vWF, whereas infusions of high-purity concentrates of factor VIII:C are not effective because of the lack of vWF. Vitamin K is used perioperatively to reverse coagulopathy due to warfarin or liver disease and is not indicated in this scenario. Aminocaproic acid inhibits fibrinolysis and is not indicated for treating vWD.