What is the management approach for a patient without multimer testing?

Management Approach for Patients Without VWF Multimer Testing

In patients where von Willebrand factor (VWF) multimer testing is unavailable, management should focus on alternative diagnostic approaches using more widely available tests, combined with close clinical monitoring for bleeding symptoms, rather than waiting for bleeding events to occur in the patient or family members. 1

Alternative Diagnostic Approach

Initial Laboratory Evaluation

• Perform initial VWF testing panel:
  • VWF antigen (VWF:Ag)
  • VWF activity (VWF:RCo or other activity assays)
  • Factor VIII coagulant activity (FVIII:C)
  • Calculate VWF:RCo/VWF:Ag ratio

Interpretation of Initial Testing

• If VWF:RCo/VWF:Ag ratio is <0.5-0.7, suspect type 2 VWD (qualitative defect) even without multimer analysis 1
• If VWF:RCo and VWF:Ag are proportionally decreased with normal ratio, suspect type 1 VWD (quantitative defect)
• If VWF levels are extremely low or undetectable, suspect type 3 VWD

Clinical Management Strategy

For Suspected Type 1 VWD (Normal VWF:RCo/VWF:Ag Ratio)

• Treat with desmopressin (DDAVP) as first-line therapy
• Perform desmopressin trial to assess response (measure VWF levels pre- and post-administration)
• For inadequate response, use VWF-containing concentrates

For Suspected Type 2 VWD (Low VWF:RCo/VWF:Ag Ratio)

• Exercise caution with desmopressin - may be ineffective or contraindicated
• VWF-containing concentrates are typically the treatment of choice
• Important: Avoid desmopressin in suspected type 2B VWD (can worsen thrombocytopenia) 1

For Suspected Type 3 VWD (Undetectable VWF)

• VWF-containing concentrates are the only effective treatment

Monitoring and Follow-up

Regular Clinical Assessment

• Implement systematic bleeding assessment using validated bleeding assessment tools
• Monitor for spontaneous bleeding episodes (mucocutaneous bleeding, menorrhagia, etc.)
• Assess response to hemostatic challenges (surgery, dental procedures, childbirth)

Laboratory Monitoring

• Repeat VWF testing periodically to assess disease stability
• Consider testing during hemostatic challenges or bleeding episodes

Special Considerations

Family Testing

• Test first-degree family members to identify patterns of inheritance
• Family testing can provide valuable diagnostic information when multimer analysis is unavailable

Referral Criteria

• Consider referral to specialized hemostasis centers for:
  • Patients with severe or recurrent bleeding despite treatment
  • Cases where diagnosis remains unclear
  • Patients requiring major surgery or invasive procedures

Practical Pitfalls to Avoid

1. Don't wait for bleeding events to occur - proactive management is essential
2. Don't rely solely on bleeding time or PFA-100 - these tests have limited sensitivity and specificity 1
3. Don't assume all VWD types respond similarly to treatment - treatment must be tailored to suspected VWD type
4. Don't overlook acquired von Willebrand syndrome (AVWS) - especially in patients with conditions associated with high shear stress like ECMO support 2
5. Don't miss the opportunity to refer - complex cases benefit from specialized hemostasis expertise

By following this systematic approach, clinicians can effectively manage patients with suspected VWD even when multimer testing is unavailable, ensuring appropriate treatment and preventing bleeding complications.