DR Medhat MRCP

Von Willebrand's disease
- Von Willebrand's disease is the most common inherited bleeding disorder.
- The majority of cases are inherited in an autosomal dominant fashion* and
characteristically behaves like a platelet disorder i.e. epistaxis and menorrhagia are
common whilst haemoarthrosis and muscle haematomas are rare
• Role of von Willebrand factor (vWF):
It`s derived from vascular endothelium (unlike the clotting factors which are
produced in the liver.
It`s a large glycoprotein which forms massive multimers up to 1,000,000 Da in size
It Promotes platelet adhesion to damaged endothelium (i.e acts as an anchor).
It`s a carrier molecule for factor VIII.
• Types :
Type 1: partial reduction in vWF (80% of patients)
Type 2: abnormal form of vWF.
Type 3: total lack of vWF (autosomal recessive).
• Presentation :
Skin easily bruises (skin petechae)
Since
Unexplained bleeding e.g epistaxis , menorrhagia Childhood
• Investigations :
New test called PFA-100 has > 95%
Prolonged bleeding time.(screening test)
APTT may be mild prolonged.
sensitivity to diagnose VWD
Plasma actor VIII activity (diagnostic test)
Defective platelet aggregation with ristocetin.
• Management :
Tranexamic acid for mild bleeding
سؤال
Desmopressin (DDAVP): raises levels of vWF by inducing release of vWF from
Weibel-Palade bodies in endothelial cells
Factor VIII concentrate.
سؤال Remember:
- Type 1 VWD :
The most useful test in practice to assess bleeding tendency in a patient
known to have VWD is vWBD antigen and activity (RICOF) OR plasma factor
VIII activity
Bleeding time is a good screening test to diagnose VWD but not for
assessment of bleeding tendency in a patient already known to have VWD
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