Answer:
Prolonged PT
Prolonged PT is not common to both classic hemophilia and classic von Willebrand's disease.
Explanation:
Classic hemophilia (Hemophilia A) and classic Von Willebrand's disease (vWD) are both disorders that affect blood clotting, but they do so in different ways. Let's analyze the options provided:
a. Prolonged PT (Prothrombin Time): PT is usually normal in both Hemophilia A and vWD because PT measures the extrinsic pathway of coagulation, which is not typically affected by deficiencies in Factor VIII or von Willebrand factor..
b. Prolonged PTT (Partial Thromboplastin Time): PTT is prolonged in both conditions. Hemophilia A involves a deficiency in Factor VIII, which is part of the intrinsic pathway measured by PTT. In vWD, there may also be a prolonged PTT due to the role of von Willebrand factor in stabilizing Factor VIII.
c. Prolonged Bleeding Time: Bleeding time is prolonged in vWD due to the role of von Willebrand factor in platelet adhesion. It may be normal or slightly prolonged in Hemophilia A depending on the severity of the factor deficiency.
d. Factor VIII diminished: In Hemophilia A, Factor VIII is diminished. In vWD, Factor VIII levels can also be reduced because von Willebrand factor protects Factor VIII from rapid degradation.