What justification is needed for von Willebrand (Von Willebrand disease) testing?

Justification for von Willebrand Disease Testing

Von Willebrand disease testing is justified when patients present with a positive bleeding history characterized by mucocutaneous bleeding symptoms (easy bruising, nosebleeds, heavy menstrual bleeding, or bleeding after surgery/procedures) or when asymptomatic patients undergoing surgical procedures answer positively to preoperative bleeding risk screening questions. 1

Clinical Scenarios Requiring VWD Testing

Symptomatic Patients

Testing should be pursued in patients presenting with:

• Personal history of mucocutaneous bleeding including easy bruising, recurrent nosebleeds, heavy menstrual bleeding, gastrointestinal bleeding, or prolonged bleeding after surgery, dental procedures, or trauma 1
• Family history of bleeding disorders or bleeding symptoms consistent with VWD 1
• Unexplained bleeding symptoms that suggest a hemostatic defect 1, 2

Preoperative Screening

For asymptomatic patients scheduled for surgery or invasive procedures, the NHLBI guidelines recommend three initial screening questions 1:

1. Have you ever had prolonged bleeding from trivial wounds lasting more than 15 minutes or recurring spontaneously during the 7 days after the wound?
2. Have you ever had heavy, prolonged, or recurrent bleeding after surgical procedures such as tonsillectomy?
3. Have you ever had bruising with minimal or no apparent trauma, especially if you could feel a lump under the bruise?

If any response is positive, proceed to nine additional detailed bleeding history questions and consider laboratory evaluation. 1

Acquired von Willebrand Syndrome Considerations

Testing should also be considered when bleeding occurs in patients with conditions associated with acquired VWD (such as aortic stenosis, lymphoproliferative disorders, or other medical conditions causing abnormal VWF), even without a family history of bleeding 1

Structured Bleeding History Assessment

An increasing number of positive responses to bleeding history questions directly correlates with higher likelihood of VWD, making the bleeding history the cornerstone for determining who needs testing. 1, 2

The nine detailed questions (Box 1 from NHLBI guidelines) assess:

• Severity and frequency of epistaxis
• Cutaneous bleeding and bruising patterns
• Bleeding from minor wounds
• Oral cavity bleeding
• Gastrointestinal bleeding
• Hematuria
• Heavy menstrual bleeding (in women)
• Postpartum hemorrhage
• Surgical and dental procedure bleeding 1

Physical Examination Findings

Physical examination should identify:

• Evidence of recent bleeding: ecchymoses, hematomas, petechiae 1
• Alternative causes of bleeding: signs of liver disease (jaundice), splenomegaly, joint and skin laxity (Ehlers-Danlos syndrome), telangiectasia (hereditary hemorrhagic telangiectasia), or anemia 1

Important Caveats

When NOT to Test

• Do not order VWD testing based solely on abnormal PT/aPTT without clinical bleeding history, as these tests do not screen for VWD and can be normal in VWD patients 1, 3
• Avoid testing during acute illness, pregnancy, or while on oral contraceptives as these conditions artificially elevate VWF levels and can produce false-negative results 4, 2

Common Pitfalls

• Failing to obtain a structured bleeding history before ordering tests leads to inappropriate testing and misdiagnosis 2, 5
• Testing patients without clinical justification (no bleeding symptoms or risk factors) results in false-positive results requiring unnecessary follow-up 6, 7
• Not considering that blood type O individuals have inherently 25-30% lower VWF levels, which can complicate interpretation 4, 2

Special Populations

In pediatric cases with suspected child abuse and intracranial hemorrhage, VWD testing may be indicated as part of the differential diagnosis, though intracranial hemorrhage is extremely rare in VWD and its presence does not definitively attribute bleeding to VWD even if test results are abnormal. 1

Testing Algorithm After Clinical Justification

Once clinical justification is established, initial laboratory evaluation should include:

• Complete blood count (CBC), prothrombin time (PT), and activated partial thromboplastin time (aPTT) to exclude other causes like thrombocytopenia or coagulation factor deficiencies 1, 4
• Three essential VWD-specific tests simultaneously: VWF antigen (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo), and factor VIII coagulant activity (FVIII) 1, 4

If the bleeding history is strong, consider ordering the VWD-specific assays at the initial visit rather than waiting for CBC/PT/aPTT results. 1