If a patient has hemophilia B and antibodies against factor IX, which factor should be administered?

• A. Prothrombin complex concentrate
• B. Recombinant activated factor VII (rFVIIa)
• C. Factor IX concentrate
• D. Factor VIII concentrate

Answer: (B)

In the case of a patient with hemophilia B and antibodies against factor IX, administering recombinant activated factor VII (rFVIIa) is the most appropriate choice. This is because rFVIIa works independently of factor IX, which means it can bypass the deficiencies caused by the antibodies targeting factor IX. This recombinant factor activates the extrinsic pathway of the coagulation cascade, leading to the activation of thrombin and subsequent formation of fibrin, which aids in hemostasis despite the presence of inhibitors.

Using prothrombin complex concentrate would not specifically address the underlying issue in the context of hemophilia B due to factor IX inhibition. Although they contain factor IX, if the patient has antibodies against it, administration may not result in effective hemostasis. Factor IX concentrate is similarly ineffective for the same reason; the presence of inhibitors means that simply providing more factor IX will not suffice. Factor VIII concentrate is specific to hemophilia A and does not play a role in hemophilia B, making it inappropriate for this situation.

Thus, rFVIIa is the optimal choice as it provides hemostatic support without relying on factor IX, which is compromised.