Von Willebrand disease (VWD) is an inherited bleeding disorder that is caused by deficiency or dysfunction of von Willebrand factor (VWF), a plasma protein that mediates the initial adhesion of platelets at sites of vascular injury and also binds and stabilizes blood clotting factor VIII (FVIII) in the circulation. Therefore, defects in VWF can cause bleeding by impairing platelet adhesion or by reducing the concentration of FVIII.
VWD is a relatively common cause of bleeding, but the prevalence varies considerably among studies and depends strongly on the case definition that is used. VWD prevalence has been estimated in several countries on the basis of the number of symptomatic patients seen at hemostasis centers, and the values
range from roughly 23 to 110 per million population (0.0023 to 0.01 percent)
Suggested Questions to Ask Patients in Screening
1. Do you have a blood relative who has a bleeding disorder, such as von Willebrand disease or hemophilia?
2. Have you ever had prolonged bleeding from trivial wounds, lasting more than 15 minutes or recurring spontaneously during the 7 days after the wound?
3. Have you ever had heavy, prolonged, or recurrent bleeding after surgical procedures, such as tonsillectomy?
4. Have you ever had bruising, with minimal or no apparent trauma, especially if you could feel a lump under the bruise?
5. Have you ever had a spontaneous nosebleed that required more than 10 minutes to stop or needed medical attention?
6. Have you ever had heavy, prolonged, or recurrent bleeding after dental extractions that required medical attention?
7. Have you ever had blood in your stool, unexplained by a specific anatomic lesion (such as an ulcer in the stomach, or a polyp in the colon), that required medical attention?
8. Have you ever had anemia requiring treatment or received blood transfusion?
9. For women, have you ever had heavy menses, characterized by the presence of clots greater than an inch in diameter and/or changing a pad or tampon more than hourly, or resulting in anemia or low iron level?
If the patient answers yes to one or more of the above:
An initial hemostasis laboratory evaluation usually includes a platelet count and complete blood count (CBC), partial thromboplastin time (PTT), prothrombin time (PT), and optionally either a fibrinogen level or a thrombin time (TT).
If these are suggestive of VWB, then the initial tests commonly used to detect VWD or low VWF are:
- VWF:Ag -- an immunoassay that measures the
concentration of VWF protein in plasma.
- VWF:RCo -- a functional assay of VWF that measures
its ability to interact with normal platelets.
- FVIII coagulant assay -- a measure of the cofactor
function of the clotting factor, FVIII, in plasma.
There is a very nice section on management. For me, it is probably best to work with the patient's Hematologist as it is very dependent on which type of VWB's the patient has and what type of injury (laceration, etc) or surgery (repair of laceration, breast reduction, etc). I did a breast reduction on a Type I VWB a couple of years ago with suggested DDAVP (Desmopressin: 1-desamino-8-D-arginine vasopressin) therapy preoperatively. The patient hardly bled or bruised. By working together, it worked well for all of us.
The guidelines can be read in its entirety here (PDF file).
Also, available for CME credit through Medscape: Management of Surgical Patients with VWD: New Research-based Options [CME available through May 5, 2009];released May 5, 2008; Joan Cox Gill, MD; Prasad Mathew, MD