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Difficulty: MediumMedical History Evaluation

A 28-year-old woman presents to the preoperative clinic for medical clearance prior to an elective septoplasty. During the clinical interview, she mentions having heavy menstrual periods that frequently require changing pads every 2 hours during the first three days of her cycle. She also recalls an incident at age 18 when a wisdom tooth extraction resulted in continuous oozing of blood for over 24 hours, requiring a return visit to the oral surgeon for suturing and packing. She has no history of spontaneous joint swelling or gastrointestinal bleeding. Her medical history is significant only for mild iron deficiency anemia, for which she takes an over-the-counter iron supplement. She takes no other medications and does not use nonsteroidal anti-inflammatory drugs. Vital signs are within normal limits. Physical examination reveals no petechiae, ecchymoses, or hepatosplenomegaly. Preoperative laboratory testing shows:

Hemoglobin: 11.8 g/dL
Platelet count: 240,000/mm³
Prothrombin time (PT): 11 seconds (Reference: 11-15 seconds)
Activated partial thromboplastin time (aPTT): 28 seconds (Reference: 25-40 seconds)

Based on the patient's medical history, which of the following is the most appropriate next step in evaluation?

  1. Measurement of von Willebrand factor antigen and ristocetin cofactor activityAnswer
  2. B
    Medical clearance to proceed with surgery without further hematologic testing
  3. C
    Measurement of Factor VIII and Factor IX activity levels
  4. D
    Performance of a plasma mixing study
  5. E
    Evaluation with light transmission platelet aggregometry

Answer

Measurement of von Willebrand factor antigen and ristocetin cofactor activity
This patient's history of heavy menstrual bleeding and prolonged bleeding following a dental extraction strongly suggests an underlying primary hemostatic defect, most likely von Willebrand disease (vWD). vWD is the most common inherited bleeding disorder and classically presents with mucosal bleeding. Because von Willebrand factor stabilizes Factor VIII, a severe deficiency can prolong the aPTT. However, in the majority of patients with mild-to-moderate vWD, Factor VIII levels remain high enough to maintain a normal aPTT. Therefore, a compelling clinical history of bleeding necessitates specific testing (vWF antigen, ristocetin cofactor activity, and Factor VIII level) even when routine coagulation studies are normal.

Step-by-Step Solution

1
Analyze the patient's clinical history.
The patient reports significant menorrhagia and a history of prolonged bleeding after a dental extraction.
Identifying patterns of bleeding (mucosal versus deep tissue) is the first step in categorizing a potential hemostatic defect.
2
Evaluate the routine laboratory results in the context of the history.
The PT, aPTT, and platelet count are entirely normal despite the positive bleeding history.
Normal routine labs do not rule out all bleeding disorders; they primarily rule out severe factor deficiencies, significant thrombocytopenia, and overt disseminated intravascular coagulation.
3
Correlate the mucosal bleeding pattern with disorders that can present with normal screening labs.
Von Willebrand disease (vWD) is the most common cause of mucosal bleeding and frequently presents with a normal aPTT in mild-to-moderate cases.
Selecting the next best diagnostic step requires targeting the most epidemiologically likely disorder that fits both the positive history and the negative screening labs.

Key Concept

A compelling clinical history of mucosal bleeding requires specific testing for von Willebrand disease, even when routine coagulation studies (PT, aPTT, platelets) are normal.
Estimated Time:1m 15s
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Topics

Medical History Evaluation

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