How likely is it that an individual surgeon would encounter a patient with type 2B von Willebrand disease (VWD) or platelet-type von Willebrand disease?

Likelihood of a Surgeon Encountering a Patient with Type 2B von Willebrand Disease or Platelet-Type von Willebrand Disease

A surgeon is extremely unlikely to encounter a patient with Type 2B von Willebrand disease or platelet-type von Willebrand disease, as these are rare subtypes of an already uncommon bleeding disorder, with Type 2B accounting for less than 5% of all VWD cases and platelet-type VWD being even rarer, constituting approximately 15% of patients initially diagnosed with Type 2B VWD. 1, 2

Epidemiology of von Willebrand Disease

• Von Willebrand Disease (VWD) affects up to 1% of the general population 3, 4
• VWD is classified into three main types:
  • Type 1: Partial quantitative deficiency (~75% of all VWD cases)
  • Type 2: Qualitative deficiency with four subtypes (2A, 2B, 2M, 2N)
  • Type 3: Complete deficiency (extremely rare, ~1 in 1,000) 3, 4

Prevalence of Type 2B and Platelet-Type VWD

• Type 2B VWD accounts for less than 5% of all VWD patients 1
• Platelet-type VWD (PT-VWD) is even rarer and often misdiagnosed
• According to international studies, PT-VWD constitutes approximately 15% of patients initially diagnosed with Type 2B VWD 5, 2

Mathematical Probability Calculation

Given these statistics, we can estimate the likelihood of a surgeon encountering these specific subtypes:

1. If VWD affects up to 1% of the population
2. And Type 2B accounts for less than 5% of VWD cases
3. Then Type 2B VWD affects approximately 0.05% (0.01 × 0.05) or 1 in 2,000 people
4. PT-VWD, being 15% of misdiagnosed Type 2B cases, would be even rarer

Diagnostic Challenges

The likelihood of encountering these patients is further complicated by diagnostic challenges:

• PT-VWD is frequently misdiagnosed as Type 2B VWD due to similar laboratory findings 5, 2
• PT-VWD may be misdiagnosed as idiopathic thrombocytopenic purpura 2
• Definitive diagnosis requires genetic testing to identify mutations in either:
  • VWF gene (indicating Type 2B VWD)
  • Platelet GP1BA gene (confirming PT-VWD) 5, 2

Clinical Significance for Surgeons

While rare, recognizing these conditions is important for surgeons because:

• Patients with Type 2B or PT-VWD may present with thrombocytopenia and bleeding diathesis 1, 6, 7
• Treatment approaches differ significantly:
  • Type 2B VWD is treated with VWF/FVIII concentrates
  • PT-VWD should be treated with platelet concentrates 5
• Acquired von Willebrand syndrome can also occur in approximately 20% of patients with severe aortic stenosis, which surgeons may encounter more frequently 3

Conclusion

For an individual surgeon, the probability of encountering a patient with Type 2B VWD or PT-VWD is extremely low, but proper identification is critical when it does occur to ensure appropriate perioperative management and prevent unnecessary bleeding complications.