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