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Zorluk: ZorHematology and Oncology

A 24-year-old woman is seen in the ambulatory care center for evaluation of easy bruising and frequent nosebleeds. She reports that her epistaxis occurs spontaneously and often requires up to 20 minutes of direct compression to resolve. Furthermore, she has experienced exceptionally heavy menstrual bleeding since menarche, frequently bleeding through super-absorbent tampons every 2 hours during the heaviest days of her cycle. Last month, a dental extraction was complicated by continuous mucosal oozing that persisted for 48 hours. She has no other medical conditions and does not take any prescription or over-the-counter medications. Her vital signs are within normal limits. Physical examination reveals several small ecchymoses on her bilateral lower extremities, but no petechiae, hemarthroses, or hepatosplenomegaly are noted. The physician suspects an underlying inherited bleeding diathesis.

Arrange the following steps in the diagnostic and management algorithm for this patient in the correct chronological sequence, from initial screening to therapeutic planning.

  1. 1Obtain a complete blood count, prothrombin time, and activated partial thromboplastin time
  2. 2Measure von Willebrand factor antigen, ristocetin cofactor activity, and factor VIII levels
  3. 3Perform a von Willebrand factor multimer analysis
  4. 4Administer a trial of desmopressin (DDAVP) to determine therapeutic responsiveness

Cevap

The correct chronological sequence is: 1) Initial coagulation screen (CBC, PT, aPTT), 2) Confirmatory factor assays (vWF antigen, ristocetin cofactor activity, factor VIII), 3) Subtype determination (vWF multimer analysis), and 4) Treatment planning (DDAVP trial).
The correct sequence follows the standard diagnostic and management algorithm for von Willebrand disease (vWD). First, an initial hemostatic screen (CBC, PT, aPTT) is required to rule out thrombocytopenia and other broad coagulation defects. Second, once the screen suggests a primary hemostatic defect, specific confirmatory quantitative and qualitative assays (vWF antigen, ristocetin cofactor activity, factor VIII) are performed. Third, after vWD is confirmed, a multimer analysis is conducted to determine the specific subtype (Type 1, 2, or 3), which dictates pathophysiology. Finally, a desmopressin (DDAVP) challenge is administered in a non-bleeding state to assess if the patient has a sufficient release of endogenous vWF and factor VIII, which establishes whether DDAVP can be safely and effectively utilized for future bleeding episodes or surgical prophylaxis.

Adım Adım Çözüm

1
Perform initial hemostatic screening
Identifies a normal platelet count, normal prothrombin time, and potentially mildly prolonged aPTT.
Broadly categorizes the bleeding diathesis and rules out thrombocytopenia or factor deficiencies in the extrinsic/common pathways before pursuing specialized testing.
2
Perform confirmatory von Willebrand disease testing
Demonstrates quantitative or qualitative deficiencies in von Willebrand factor and secondary decreases in factor VIII.
Establishes the definitive diagnosis of von Willebrand disease based on the abnormal screening results and bleeding history.
3
Determine the disease subtype
Characterizes the size distribution of von Willebrand factor multimers.
Differentiates between quantitative defects (Type 1, 3) and qualitative defects (Type 2), which is clinically necessary for guiding specific therapies and avoiding contraindicated treatments.
4
Assess therapeutic responsiveness
Evaluates the patient's rise in von Willebrand factor and factor VIII following the administration of desmopressin (DDAVP).
Determines if DDAVP induces sufficient endogenous factor release to be used for future bleeding episodes or surgical prophylaxis.

Anahtar Kavram

Diagnostic and management sequence for von Willebrand disease
Tahmini Süre:1m 30s
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Konular

Hematology and Oncology

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