A patient with mucocutaneous bleeding and prolonged bleeding time most likely has which defect?

• A. Hemophilia A
• B. Von Willebrand disease
• C. Thrombocytopenia
• D. Vitamin K deficiency

Answer: (B)

Defects in primary hemostasis that impair platelet adhesion lead to mucocutaneous bleeding and a prolonged bleeding time. Von Willebrand factor is essential for platelets to stick to damaged endothelium, via the platelet receptor GPIb, and it also stabilizes factor VIII. When von Willebrand factor is deficient or dysfunctional, platelets don’t adhere well, so bleeding from mucosal surfaces is common and takes longer to stop, yielding a prolonged bleeding time. Some cases may also have a reduced factor VIII level because von Willebrand factor protects VIII, but the key feature is the defective platelet adhesion that shows up as an increased bleeding time.

In contrast, hemophilia A is a factor VIII deficiency that mainly causes deep tissue and joint bleeding with a prolonged PTT rather than a prolonged bleeding time; thrombocytopenia can cause mucocutaneous bleeding as well but stems from low platelet count, not a defective adhesion process; vitamin K deficiency affects synthesis of several coagulation factors and typically prolongs PT (and often aPTT) rather than bleeding time.