Makindo Medical Notes

Related Subjects: |Sideroblastic Anaemia |Splenectomy |Blood Products - Platelets |Von Willebrand Disease

Patients with von Willebrand disease (vWD) may experience mucosal bleeding, including excessive bleeding after surgical procedures (e.g., dental extraction) and unusually heavy menstrual bleeding. Aspirin and NSAIDs should be avoided due to the risk of exacerbating bleeding. Tranexamic acid is often used to reduce bleeding episodes.

About

• Von Willebrand disease (vWD) is the most common inherited bleeding disorder, characterized by both platelet dysfunction and a deficiency of clotting factor VIII.
• It is primarily inherited in an autosomal dominant (AD) manner, but autosomal recessive (AR) forms also exist. There are 22 known subtypes of the disease.
• Unlike hemophilia, which predominantly affects males, vWD affects both males and females equally.
• The gene for von Willebrand factor (vWF) is located on chromosome 12 and can have several mutations, leading to variable clinical presentations.

Aetiology

• Von Willebrand factor (vWF) functions as a "bridge," binding platelets to collagen in the blood vessel wall during clot formation.
• It binds to the GP1b receptor on platelets and to collagen in the vessel, while the GP1a receptor on platelets binds directly to collagen.
• Platelets release ADP, thromboxane A₂ (TXA₂), and serotonin once attached, which helps in clot formation.
• vWF also stabilizes and carries factor VIII, a key clotting factor, preventing its rapid degradation in circulation.

Types of Von Willebrand Disease

Investigations

• Prolonged bleeding time due to platelet dysfunction, despite normal platelet count.
• Prolonged activated partial thromboplastin time (APTT) due to factor VIII deficiency.
• Normal prothrombin time (PT).
• Low levels of factor VIII:vWF and factor VIII:C (clotting activity).
• Ristocetin cofactor assay shows impaired platelet aggregation, diagnostic of vWD.

Management

• Avoid aspirin, NSAIDs, and intramuscular (IM) injections to prevent bleeding complications.
• Desmopressin (DDAVP): Used in Types 1 and 2, this drug stimulates the release of stored vWF from endothelial cells, increasing vWF and factor VIII levels.
• Factor VIII:vWF concentrate: Given before surgery or in severe bleeding episodes, especially in Type 3 patients.
• Tranexamic acid may be used to reduce bleeding, particularly during surgery or heavy menstrual periods.
• Patients with severe forms, such as Type 3, should be closely monitored for bleeding, especially during invasive procedures.
• Genetic counseling may be offered to families with inherited forms of vWD.