What is the most likely diagnosis for a 19-year-old female with persistent bleeding, easy bruising, heavy menstrual cycles, and lab results showing decreased factor eight activity and normal factor nine activity?

Von Willebrand Disease

The most likely diagnosis is von Willebrand disease (VWD), given the constellation of lifelong mucocutaneous bleeding (easy bruising, menorrhagia since menarche), maternal history of bleeding disorder, post-procedural bleeding after dental extraction, prolonged aPTT with mildly decreased factor VIII activity, and normal platelet count. 1

Clinical Reasoning Algorithm

Step 1: Pattern Recognition of Bleeding Symptoms

• Mucocutaneous bleeding pattern is the hallmark of VWD, including easy bruising, heavy menstrual bleeding, nosebleeds, and bleeding after dental procedures 1
• This patient demonstrates the classic triad: lifelong bleeding history, menorrhagia since menarche, and post-procedural bleeding after wisdom tooth extraction 1
• The maternal history of bleeding disorder supports an autosomal inheritance pattern, which is characteristic of VWD affecting males and females equally 1

Step 2: Laboratory Profile Analysis

The laboratory findings definitively point toward VWD:

• Prolonged aPTT (51 seconds) with normal PT (11.5 seconds) indicates a defect in the intrinsic coagulation pathway 1
• Mildly decreased factor VIII activity (64%) occurs because VWF carries and stabilizes factor VIII in circulation; VWF deficiency leads to secondary factor VIII reduction 1, 2
• Normal platelet count (360) rules out immune thrombocytopenia 1
• Normal factor IX activity (90%) excludes hemophilia B 1

Step 3: Excluding Alternative Diagnoses

Disseminated Intravascular Coagulation (DIC):

• Ruled out by normal platelet count, normal PT, and absence of systemic illness 1
• DIC would show thrombocytopenia, prolonged PT and aPTT, and elevated D-dimer

Hemophilia A:

• Extremely unlikely in a female patient (X-linked recessive disorder) 1
• Would require homozygosity or Turner syndrome, neither suggested here
• Factor VIII at 64% is too high for symptomatic hemophilia A

Hemophilia B:

• Excluded by normal factor IX activity (90%) 1

Immune Thrombocytopenia:

• Excluded by normal platelet count (360) 1

Step 4: Understanding VWD Pathophysiology in This Case

VWD causes bleeding through dual mechanisms: 2

• Impaired platelet adhesion at sites of vascular injury (explaining mucosal bleeding, easy bruising, and post-extraction bleeding)
• Secondary factor VIII deficiency due to loss of VWF carrier function (explaining prolonged aPTT and mildly reduced factor VIII)

The factor VIII level of 64% is consistent with Type 1 VWD (partial quantitative VWF deficiency), which accounts for approximately 75% of symptomatic VWD cases 1

Critical Clinical Pearls

Common Pitfalls to Avoid:

• Do not dismiss VWD based on "borderline" factor VIII levels - levels between 50-70% are common in Type 1 VWD and still cause significant bleeding 1
• Do not confuse with hemophilia A - the female sex, mucocutaneous bleeding pattern, and family history through the maternal line all favor VWD over hemophilia 1
• Do not overlook the menorrhagia history - 5-20% of women with menorrhagia have previously undiagnosed VWD 3

Immediate Management Considerations:

Given the active post-extraction bleeding with hemoglobin of 9.2 g/dL (indicating significant blood loss):

• Desmopressin 0.3 μg/kg IV is first-line therapy for Type 1 VWD, raising endogenous VWF and factor VIII levels 3-6 fold within 30-90 minutes 4, 5, 6
• Local hemostatic measures including firm compression and resorbable packing materials 4
• Tranexamic acid as adjunctive antifibrinolytic therapy 6, 7

Next Diagnostic Steps:

Complete VWD workup requires: 8, 9

• VWF antigen levels (quantitative measurement)
• VWF activity assays (ristocetin cofactor activity or glycoprotein Ib binding)
• VWF multimer analysis for subtyping if Type 2 variants suspected
• Referral to hematology or hemophilia treatment center for definitive diagnosis and subtype classification 3