Von Willebrand's Disease

Incidence

 

Most common of the bleeding disorders

- 1:100

 

Function

 

vWF            

- needed for platelet adhesion and platelet-platelet interactions

- also carrier for factor VIII / protects it from rapid breakdown

 

Aetiology

 

Gene on chromosome 12

1.  Reduced production VWF

2.  Increased proteolysis VWF

 

Leads to diminished platelet adherence at sites of vascular injury

 

3 types

 

Type I      

- quantitative deficit

- mild reduction in VIII:vWF / AD

 

Type II     

- qualitative deficit

- reduction in proportion of HMW multimers / AD

- mild clinical features, bleeding post-surgery, epistaxis

 

Type III    

- barely detectable FVIII:vWF (= VIII:C) / AR

- clinically resembles Haemophilia A

 

Investigations

 

Bleeding times

- prolonged with normal platelet count

 

APTT

- slightly increased

 

vWF assay

- Ag based test

 

VIII:C

- decreased levels

 

Clinical

 

Positive FHx

 

Common history

- easy bruising

- bleeding post circumcision

- menorragia / post partum bleeding

- nose bleeds, gum bleeding

- bleeding post dental extraction

 

Severe hemarthrosis

- type III

 

Management

 

Mild disease

 

Desmopressin / DDAVP

- stimulates release of vWF from endothelial cells

- useful only in type 1 / quantitative deficit

 

Surgery

 

Cryoprecipitate

- 1 bag / 10 kg bd

- several days after major operation