What is the next appropriate test for a 14-year-old female with menorrhagia (heavy menstrual bleeding), easy bruising, and prolonged bleeding from cuts, with normal complete blood count (CBC), platelet count, partial thromboplastin time (PTT), prothrombin time (PT), and fibrinogen levels?

Next Appropriate Test: Von Willebrand Disease Screening

The next appropriate test is von Willebrand disease (VWD) screening, which requires three simultaneous assays: VWF antigen (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo), and Factor VIII coagulant activity (FVIII). 1

Clinical Reasoning

This 14-year-old female presents with the classic triad of mucocutaneous bleeding symptoms—menorrhagia, easy bruising, and prolonged bleeding from cuts—with normal initial coagulation studies. This presentation is highly suggestive of von Willebrand disease, which is the most common inherited bleeding disorder (prevalence 1 in 1,000) and is not reliably detected by standard PT/PTT screening. 2

Why VWD is the Leading Diagnosis

• VWD affects 11-16% of women with menorrhagia and normal gynecological evaluation, making it the most likely diagnosis in this clinical scenario 3, 4
• Normal PT, PTT, platelet count, and fibrinogen levels do not exclude VWD, as these tests do not assess von Willebrand factor function 5, 2
• The mucocutaneous bleeding pattern (menorrhagia, easy bruising, prolonged bleeding from cuts) is characteristic of VWD rather than coagulation factor deficiencies 1, 6

Required Testing Protocol

All three VWD assays must be ordered simultaneously to avoid misdiagnosis: 1

• VWF antigen (VWF:Ag): Measures the quantity of VWF protein
• VWF ristocetin cofactor activity (VWF:RCo): Measures VWF function
• Factor VIII coagulant activity (FVIII): Measures FVIII levels, which are often reduced in VWD

Normal reference ranges for all three tests are 50-200 IU/dL. 1

Diagnostic Thresholds

• VWF:RCo <30 IU/dL = definitive VWD diagnosis 1
• VWF:RCo 30-50 IU/dL with supportive clinical/family history = likely VWD 1
• VWF:RCo/VWF:Ag ratio <0.5-0.7 suggests Type 2 (qualitative) VWD rather than Type 1 (quantitative deficiency) 1

Critical Pre-Analytical Considerations

Proper sample handling is essential to avoid false results: 1

• Atraumatic blood draw with minimal patient stress
• Avoid testing during acute illness, pregnancy, or recent oral contraceptive use (these elevate VWF levels) 1, 2
• Transport samples at room temperature
• Separate plasma promptly at room temperature
• If testing delayed >2 hours, freeze samples at ≤-40°C 1

Important Caveat

VWF is an acute phase reactant and levels can be falsely elevated during stress or illness, requiring repeated testing if initial results are borderline normal. 2 The VWF:RCo assay has high coefficient of variation (10-30%), which may necessitate repeat testing. 1

Alternative Considerations if VWD Testing is Normal

If VWD testing returns normal but clinical suspicion remains high, platelet function testing should be the next step, as platelet function disorders can present identically but are not detected by routine coagulation studies or VWD assays. 7, 3

Platelet function testing includes: 7

• Light transmission aggregometry with multiple agonists (ADP, collagen, epinephrine, ristocetin, arachidonic acid)
• Platelet flow cytometry to evaluate surface glycoproteins

Additional rare bleeding disorder testing may include: 7

• Factor XIII activity (often overlooked but can cause significant bleeding)
• Fibrinolysis defects (extremely rare)
• Rare coagulation factor assays (FII, FV, FVII, FX)

When to Refer to Hematology

Immediate referral to pediatric hematology is indicated for: 1

• Abnormal initial VWD assay results requiring subtyping
• Strong bleeding history with repeatedly normal tests
• Guidance on repeat testing interpretation
• Access to specialized assays (VWF multimer analysis, platelet aggregation studies)