The Coombs Direct Test is performed to measure the level of antibodies attached to the Red Blood Cells in the blood. The test helps detect haemolytic anaemia, Rh negative pregnancy, and transfusion reactions. Your doctor might ask you to get the test done if you have haemolytic anaemia and he or she wants to find out the cause. You might also be asked to get the test done if you have symptoms such as bloody urine, back pain, chills, etc.