The indirect Coombs test is used only in prenatal testing of pregnant women and in testing blood prior to a transfusion.Test is Done for : Antibody screening and cross matching prior to blood transfusion, Prenatal testing of pregnant woman. To detect and identify auto-antibodies in acquired hemolytic anemia. Pregnant women get a prenatal antibody screening with an indirect Coombs test. It checks the mothers blood to see if there are antibodies that could pass to and harm their unborn baby.