Red Blood Cell Antibody Screen

An RBC (red blood cell) antibody screen is a blood test that looks for RBC antibodies in your blood. These antibodies destroy red blood cells that are foreign (different from your own). Antibodies are proteins that your immune system makes to attack germs and other foreign substances in your body, including red blood cells that aren't like yours.

Your immune system recognizes foreign red blood cells by chemical markers on the cells, called antigens. All red blood cells have antigens. Your blood type is based on the kind of antigens you have on your cells.

The main antigens found on red blood cells are A, B, and Rh Factor (also called D antigen). If you're exposed to red blood cells with antigens that aren't like yours, the foreign antigens will trigger your immune system to make RBC antibodies to destroy the foreign red blood cells. You may have RBC antibodies in your blood if you have been exposed to foreign red blood cells in a blood transfusion, or if you have been pregnant with a fetus whose blood type was different from your own.

RBC antibodies that attack foreign blood cells won't harm your health, but these antibodies could cause problems if you are exposed to foreign red blood cells again, for example: If you have a blood transfusion, RBC antibodies could cause serious illness.; If you are pregnant with a fetus who has a blood type that's different from yours, certain RBC antibodies could harm your fetus.; Once your body makes RBC antibodies, you will always have them.

Why this test is done

Your provider may order an RBC antibody screen if:

• You need a blood transfusion. The test helps make sure you get donor blood that's safe for you.
• You're pregnant. The test is usually done in early pregnancy, as part of routine prenatal testing. The test helps your provider know what care you will need during your pregnancy.

How to prepare

You don't need any special preparations for an RBC screen.

Sample type

Blood

Other names for this test

antibody screen, indirect antiglobulin test, indirect anti-human globulin test, IAT, indirect coombs test, erythrocyte Ab, RBC antibody identification