If a patient is tested for type 2 von Willebrand disease (VWD) within two weeks of tissue trauma, such as surgery or colonoscopy, and has a normal von Willebrand factor (VWF) antigen activity ratio, does that rule out type 2 VWD?

Testing for Type 2 von Willebrand Disease After Tissue Trauma

A normal VWF antigen activity ratio of 0.9 obtained within two weeks of tissue trauma does not rule out type 2 von Willebrand disease (VWD), as VWF levels can be temporarily elevated due to the acute phase response following surgery or procedures.

Understanding VWF Testing After Tissue Trauma

Tissue trauma from procedures like surgery or colonoscopy can significantly affect VWF levels and ratios due to the acute phase response. This creates important considerations when interpreting test results:

• VWF is an acute phase reactant that increases following tissue trauma
• Surgery, colonoscopy, and other invasive procedures can temporarily elevate VWF levels
• This elevation can mask underlying qualitative defects in VWF

Key Diagnostic Parameters for Type 2 VWD

Type 2 VWD is characterized by qualitative defects in VWF function rather than just reduced quantity. According to guidelines, the following laboratory findings are characteristic of type 2 VWD 1:

• VWF:RCo/VWF:Ag ratio <0.5-0.7 suggests type 2 VWD
• Type 2A: Loss of high and intermediate molecular weight multimers
• Type 2B: Loss of high molecular weight multimers with enhanced RIPA at low doses
• Type 2M: Normal multimer pattern but decreased function
• Type 2N: Normal VWF:RCo and VWF:Ag but low FVIII:C

Why Your Patient's Result May Be Misleading

The normal ratio of 0.9 in your patient is likely influenced by the recent tissue trauma:

1. Acute phase response: Surgery or colonoscopy triggers increased production of VWF
2. Temporary normalization: This can temporarily normalize the VWF:RCo/VWF:Ag ratio
3. Masking effect: The increased VWF production can mask underlying qualitative defects

Recommended Approach

To properly diagnose or exclude type 2 VWD in this scenario:

1. Repeat testing: Guidelines recommend repeating VWF testing when the patient is in a baseline state, at least 2-4 weeks after any tissue trauma 1
2. Multiple tests: Testing may need to be repeated up to 3 times to ensure reliable results
3. Complete panel: Include VWF:Ag, VWF:RCo, VWF:CB, and FVIII coagulant activity
4. Multimer analysis: Consider VWF multimer analysis to identify specific structural abnormalities

Clinical Pearls and Pitfalls

• Common pitfall: Relying on a single test performed during the acute phase response
• Important consideration: VWF levels can vary significantly based on numerous factors including stress, inflammation, and hormonal status
• Key point: A normal VWF:RCo/VWF:Ag ratio during acute phase response does not exclude type 2 VWD
• Warning sign: If the patient has a strong personal or family history of mucocutaneous bleeding, further evaluation is warranted despite normal initial testing

In patients with suspected type 2 VWD, the American Society of Hematology recommends using standardized bleeding assessment tools to objectively quantify bleeding severity and guide further testing decisions 1.