Antibody tests (Coombs tests) are done to find antibodies that attack red blood cells.Normal: No antibodies are found. This is called a negative test result.
- Direct Coombs test. A negative test result means that your blood does not have antibodies attached to your red blood cells.
- Indirect Coombs test. A negative test result means that your blood is compatible with the blood you are to receive by transfusion. A negative indirect Coombs test for Rh factor (Rh antibody titer) in a pregnant woman means that she has not developed antibodies against the Rh-positive blood of her baby. This means that Rh sensitization has not occurred.
- Direct Coombs test. A positive result means your blood has antibodies that fight against red blood cells. This can be caused by a transfusion of incompatible blood or may be related to conditions such as hemolytic anemia or hemolytic disease of the newborn (HDN).
- Indirect Coombs test. A positive test result means that your blood is incompatible with the donor's blood and you can't receive blood from that person. If the Rh antibody titer test is positive in a woman who is pregnant or is planning to become pregnant, it means that she has antibodies against Rh-positive blood (Rh sensitization). She will be tested early in pregnancy to check the blood type of her baby. If the baby has Rh-positive blood, the mother will be watched closely throughout the pregnancy to prevent problems to the baby's red blood cells. If sensitization has not occurred, it can be prevented by a shot of Rh immunoglobulin.
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