Von Willebrand Disease

Disease:

Pathophysiology	· Reduced binding of platelets to each other and to collagen · Reduced protection of circulating factor 8
Presentation	· Bleeding: surgery, epistaxis, gum, period · Normal platelet, INR, aPTT
Differentials	· i.e. bleeding diathesis with normal platelet, INR, aPTT o Haemophilia – joint and muscle bleeding o Abnormal platelets – very rare
Subtypes	· 1: less · 2: dysfunctional o 2A: LOF – many causes o 2B: GOF - ↑binding to platelet o 2M: LOF - ↓binding to platelet o 2N: LOF - ↓binding to factor 8 (behaves like Haemophilia) · 3: none
Problems	· High risk of surgical bleeding · High risk of neuraxial complications · Doesn’t show up on usual tests

Testing

Pre-op tests:

· vWF antigen assay

· vWF / factor 8 function assay

· DDAVP challenge

· BGHO: because blood group affects levels

Targets:

· Obstetrics >50% at delivery or neuraxial, >25% otherwise

· Major surgery >50%

· Minor surgery >30%

Treatment

General:

· Transfer to tertiary centre unless low risk

· Address all the other aspect of blood management

· Avoid all anti-platelets (includes NSAIDs)

· Avoid neuraxial procedures altogether

Specific:

· Discuss with haematology; treatment is dependent on subtype

· TXA peri-op 3-5 days

· Nothing vs desmo vs blood products

vWF sources

· DDAVP (↑level 3-5x)

o Dose 0.3mcg/kg

o Onset 30 mins

o Duration 6-8 hours

o Not useful for type 3

o Contraindicated in type 2B

o Tachyphylaxis after 4 doses

· Cryoprecipitate (small amount of vWF)

· vWF concentrates e.g. Biostate (large amount of vWF)

o Dose 60-80 units/kg