There are four different types of blood screening tests that are used to diagnose hemophilia:
Complete Blood Count
A complete blood count (CBC) measures various factors within the blood: the hemoglobin levels, the number and size of red blood cells, number of white blood cells, and the number of platelets. These results are usually normal in hemophilia patients but after a heavy bleed, the hemoglobin and red blood cells will be lower than normal.
Activated Partial Thromboplastin Time Test
The activated partial thromboplastin time (APTT) test measures the clotting efficiency of factors VIII, IX, XI, and XII. It looks for any delays in the blood clot formation, which indicates that the person has low levels of clotting factor.