Curriculum · Hematology
Haemophilia B (factor IX deficiency)
What it is
Hemophilia B is a coagulation factor deficiency of secondary hemostasis. On the coagulation profile it sits in the same row as hemophilia A: factor deficiency VIII, IX, XI, XII, antiphospholipid antibody, haemophilia A or B, and a circulating anticoagulant (heparin).
How it presents
The bleeding pattern is that of the coagulation side. Surface cuts bleed normally or only slightly longer, onset after injury is delayed, and bleeding is deep - into joints and muscles - and excessive post-traumatic, with hemarthroses and hematomas rather than petechiae and ecchymoses.