Red Blood Cell Antibody Screen
Reviewed
Also called: Antibody Screen, Indirect Antiglobulin Test, Indirect Coombs Test, IAT
An RBC (red blood cell) antibody screen is a blood test that looks for RBC antibodies in your blood.
Specimen: Blood sample from a vein in your arm
Why this test may be ordered
- Before a blood transfusion to select compatible donor blood
- During pregnancy as part of routine prenatal testing to detect antibodies that could cause fetal anemia
Preparation and collection
You don't need any special preparations for an RBC screen.
A health care professional will take a blood sample from a vein in your arm, using a small needle. This usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
Once your body makes RBC antibodies, you will always have them. But you may have too few to show up on a test.
- Negative: A negative result means that no RBC antibodies were found. Limitation: But you may have too few to show up on a test. Next step: If you are Rh-negative, your provider may give you an injection to prevent your body from making Rh antibodies.
- Positive (before a blood transfusion): A positive result means you have one or more RBC antibodies in your blood that could destroy red blood cells in certain types of donor blood. Limitation: Once you have RBC antibodies, they never go away. Next step: You will likely need more tests to find out exactly what type of RBC antibodies you have so your provider can select donor blood that's a good match for you.
- Positive (during pregnancy): A positive test result means that you have RBC antibodies in your blood that could harm your fetus. Limitation: There is no treatment to stop your body from making more Rh antibodies. Next step: If you have other RBC antibodies, but no Rh antibodies, your pregnancy will be closely watched.
- Once your body makes RBC antibodies, you will always have them, but they may be too few to show up on a test.
- A positive result requires additional tests to identify the specific antibodies.
- If you have had a previous positive RBC antibody screen, inform your provider, especially before a blood transfusion or during pregnancy.
What to do next
If you have had an RBC antibody screen that showed you have RBC antibodies, make sure to tell your provider, especially if you need a blood transfusion or are pregnant.
- What do my results mean for my blood transfusion or pregnancy?
- If I am Rh-negative, will I need an injection to prevent making Rh antibodies?
- Do I need additional testing to identify specific antibodies?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Red Blood Cell Antibody Screen