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

 

Peri-op management:

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

 

 

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