Bleeding in haemophilia A is due to:

Ans: c (Deficiency of factor 8 which fails to activate factor 10) Ref: Harrison, 16th ed, p. 680; 17th ed, p. 726Haemophilia A occurs due to deficiency or reduced activity of factor 8 which is responsible for activation of factor 10. The intrinsic pathway of coagulation is affected.Haemophilia B or Christmas disease occurs due to deficiency of factor 9Coagulation profile in haemophiliaBT-normalClotting time - increasedPTT - increasedPT-normalIf intrinsic pathway (8, 9, 11, 12) is affected - PTT is prolongedIf extrinsic pathway (5, 7) is affected - PT is prolongedIf factors 1, 2 and thrombin are affected then both PT and PTT are prolonged