Clinical recommendation	Evidence rating	References
Evaluation for VWD should be considered preoperatively for currently asymptomatic persons if personal or family history of bleeding is a concern; for persons with current symptoms or a history of increased bleeding, abnormal laboratory study results, or a family history of a bleeding disorder; and for persons with a previous VWD diagnosis, but no supporting laboratory documentation.	C	1, 3, 4
Clinical history in patients with possible VWD should focus on episodes of excessive bleeding, including spontaneity, severity, cause, sites, and duration of bleeding; and ease with which bleeding was stopped. Patients should also be asked about medication use (e.g., aspirin, clopidogrel [Plavix], heparin, nonsteroidal anti-inflammatory drugs, warfarin [Coumadin]).	C	1, 3, 4, 12–15
Initial tests for a bleeding disorder rule out more common causes of bleeding. These tests include complete blood and platelet counts, PTT, PT, and possibly fibrinogen level or thrombin time. Initial tests for VWD (VWF:Ag, VWF:RCo, factor VIII) confirm VWD.	C	3–5
Patients with isolated prolonged PTT or with normal PTT, PT, platelet count, and fibrinogen level in the presence of bleeding signs or symptoms should receive VWF:Ag, VWF:RCo, and factor VIII assays to test for VWD.	C	1, 3, 4, 7, 16