What is the definition or description of: Coombs test?

Red cell antibodies. Coombs serum is an antibody directed against other antibodies that makes antibody-coated red cells stick together. The direct coombs test seeks antibodies on a patient's own red cells that may be causing red cell damage and perhaps anemia. The indirect coombs test is used in blood banking to determine what antigens are present on unknown red cells by seeing what antibodies they bind.