The factor IX assay is the blood test used to measure the factor IX activity. It is one amongst the proteins engaged in the body that aids in blood clotting. The preliminary detection of coagulation disorder does platelet counts, bleeding time testing, PT, and aPTT. The prolonged aPTT keep normal indication of PT and early abnormality part of the intrinsic coagulation path. The actual aPTT don’t eliminate hemophilia B because of aPTT not sensitive to identify the FIX reduced levels from 20 to 30% occurs in serene hemophilia. If the clinical records warrant a particular level of FIX finds and not constant with the hemophilia B.