Start practicing

Medical Emergencies · single question

Which statement best describes the hemostatic defect in von Willebrand disease?

  1. Impaired platelet adhesion plus reduced factor VIII, producing a prolonged PTT
  2. Isolated factor IX deficiency
  3. Normal platelet function with an isolated factor VIII deficiency only
  4. A vitamin K–dependent clotting factor deficiency
Show answer and explanation

Correct answer: A. Impaired platelet adhesion plus reduced factor VIII, producing a prolonged PTT

  • A. Correct. Von Willebrand factor mediates platelet adhesion and stabilizes factor VIII. Its deficiency impairs platelet function, lowers factor VIII (prolonging PTT), and contributes to capillary fragility.
  • B. Incorrect. Factor IX deficiency is hemophilia B, a separate disorder.
  • C. Incorrect. An isolated factor VIII deficiency with normal platelet function describes classic hemophilia A, not vWD.
  • D. Incorrect. Vitamin K–dependent factor deficiency (II, VII, IX, X) is unrelated to vWF.

Practice Medical Emergencies questions Medical Emergencies study notes

More Medical Emergencies practice questions