Which condition matches: prothrombin time unaffected; partial thromboplastin time unaffected; bleeding time prolonged; platelet count unaffected?

Which condition matches: prothrombin time unaffected; partial thromboplastin time unaffected; bleeding time prolonged; platelet count unaffected?

• A. Von Willebrand disease
• B. Haemophilia
• C. Thrombocytopenia
• D. Aspirin

Answer: (A)

The main concept here is recognizing a pattern that points to a problem with primary hemostasis, not the coagulation factors. PT and aPTT measure the integrity of the coagulation cascade, so if both are normal, the clotting factors are functioning. Bleeding time reflects how well platelets form a plug at an injury site, so a prolonged bleeding time signals a platelet-related issue or a defect in von Willebrand factor that helps platelets stick to injured vessels. A normal platelet count shows it isn’t simply thrombocytopenia. In von Willebrand disease, there is a deficiency or dysfunction of von Willebrand factor, which impairs platelet adhesion to subendothelial collagen. That delays the initial platelet plug formation, lengthening bleeding time, even though the number of platelets is normal and the coagulation times (PT and often aPTT) are normal or only mildly affected. This pattern fits the scenario: prolonged bleeding time with normal platelet count and normal coagulation times. Haemophilia would typically prolong the aPTT because of intrinsic pathway factor defects, not prolong the bleeding time. Thrombocytopenia would lower platelet count, which isn’t the case here. Aspirin can prolong bleeding time by inhibiting platelet function, but it’s a drug, not a disease, and the question frames the scenario as a condition, making von Willebrand disease the best match.

The main concept here is recognizing a pattern that points to a problem with primary hemostasis, not the coagulation factors. PT and aPTT measure the integrity of the coagulation cascade, so if both are normal, the clotting factors are functioning. Bleeding time reflects how well platelets form a plug at an injury site, so a prolonged bleeding time signals a platelet-related issue or a defect in von Willebrand factor that helps platelets stick to injured vessels. A normal platelet count shows it isn’t simply thrombocytopenia.

In von Willebrand disease, there is a deficiency or dysfunction of von Willebrand factor, which impairs platelet adhesion to subendothelial collagen. That delays the initial platelet plug formation, lengthening bleeding time, even though the number of platelets is normal and the coagulation times (PT and often aPTT) are normal or only mildly affected. This pattern fits the scenario: prolonged bleeding time with normal platelet count and normal coagulation times.

Haemophilia would typically prolong the aPTT because of intrinsic pathway factor defects, not prolong the bleeding time. Thrombocytopenia would lower platelet count, which isn’t the case here. Aspirin can prolong bleeding time by inhibiting platelet function, but it’s a drug, not a disease, and the question frames the scenario as a condition, making von Willebrand disease the best match.