What is VWD?
von Willebrand disease, or VWD, is the most common inherited bleeding disorder, affecting both men and women. Because most cases of VWD are mild and may not produce noticeable symptoms, it often goes undiagnosed.
What causes VWD?
VWD occurs when von Willebrand factor (VWF), a protein that helps form blood clots to stop bleeding, is missing or doesn’t work the way it should. Because of this, when people with VWD bleed from cuts or injuries, their bleeding takes longer to stop.
The clotting process—step by step
Terms to Know
Factor VIII (FVIII): A protein in the blood, called a clotting factor, that is needed for clot formation
Coagulation cascade: A process involving the interaction of multiple clotting factors, resulting in the formation of fibrin, which strengthens the blood clot
Platelets: Blood cells that gather at the site of injury
Fibrin: A tough web-like protein that holds platelets together and keeps the clot in place
Normal clotting
Normal blood vessel
Blood vessel is injured
- VWF binds to FVIII and triggers blood platelets to join together, forming a plug to support clotting
- In this process, called platelet adhesion, platelets stick together at the site of injury
Clot forms and stabilizes
- The platelet plug is reinforced by a tough mesh of fibrin, which forms a fibrin clot
- Other clotting factors in the coagulation cascade are important in clot formation
Abnormal clotting
Normal blood vessel
Blood vessel is injured
Clot forms incorrectly or not at all
Adapted from the National Heart, Lung and Blood Institute. The Diagnosis, Evaluation, and Management of von Willlebrand disease. Bethesda, MD: National Institutes of Health; 2007. NIH publication 08-5832