Coombs test
The Coombs test checks your blood for antibodies that attack red blood cells. You might also hear it called an antiglobulin test or red blood cell antibody screening. Your immune system will make antibodies if it finds ones that don't match yours. They're keyed to specific areas on the outside of the cell. Some of these antibodies are related to your blood type. There are two types of Coombs tests. The direct test looks for antibodies that are stuck to red blood cells. The indirect test looks for antibodies floating in the liquid part of your blood, called serum.