An indirect Coombs test (or antiglobulin test) is used in prenatal testing to detect antibodies against foreign red blood cells in the mother's bloodstream. Commonly, this is used to determine if there are antibodies against Rh factor in the mother's blood. The difference between indirect and direct Coombs tests are the way in which the lab prepares the sample. A direct Coombs test is usually used to detect autoimmune hemolytic anemia, while an indirect Coombs test is used for prenatal testing and testing prior to a blood transfusion to determine compatibility between the donor and recipient. A carrier type can detect chromosomal abnormalities, though cells would need to be taken from the fetus. Prenatal testing may include testing for infectious diseases, but these are not the Coombs test.