Elderly female with a personal and family history of a bleeding disorder.

A 77-year-old woman with a history of excessive bleeding and questionable diagnosis of von Willebrand disease (VWD) presented for a presurgical evaluation. Her daughter and grandson also had a history of a bleeding disorder. Bleeding events reported by the patient and her family members included easy bruising, postsurgical bleeding and hematoma formation requiring intervention with drainage and blood products, and excessive bleeding during childbirth. The physician requested testing for VWD to confirm the diagnosis and subtype, since subclassification of VWD guides appropriate therapy. Results of the initial testing revealed typical prothrombin time (PT) (13.7 s, reference interval 12.0–15.5 s), typical activated partial thromboplastin time (aPTT) (31.5 s, reference interval 24–35 s), mild thrombocytopenia (116 K/ L, reference interval 150–450 K/ L), typical von Willebrand factor antigen level (VWF:Ag) (108%, reference interval 52%–214%), typical factor VIII activity (98%, reference interval 56%–191%), decreased von Willebrand factor ristocetin cofactor activity (VWF:RCo) (19%, reference interval 51%–215%), and decreased VWF:RCo/VWF:Ag ratio (0.18, reference interval 0.7–1.0).