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Coombs’ test is an antiglobulin test that is used to detect and identify immune antibodies in the blood. Thanks to this test, it is possible to detect, among other things, a serological conflict between the mother and the child, diagnose diseases such as listeriosis or brucellosis and prevent post-transfusion complications. What does this test look like and when does it need to be performed?
Direct antiglobulin test
Direct Coombs test (BTA) detects antibodies in blood cells, but does not check their type or source. The more such antibodies appear on red blood cells, the stronger the BTA response. This kind Coombs test it is helpful in diagnosing the cause of autoimmune haemolytic anemia, as well as in hemolytic diagnostics of the fetus and newborns when there is a serological conflict between the child and mother, and in diagnosing the causes of complications after transfusion.
Indirect Antiglobulin Test
Much more common use is applicable indirect antiglobulin test (PTA). It is currently part of a blood group test and is used to detect antibodies in the plasma, such as antibodies against red blood cell antigens other than A and B. The results of this test can not only detect the presence of antibodies, but also identify which blood cell antigens they are associated with. .
Coombs PTA test is performed primarily before blood transfusion, but also after transfusion, when a post-transfusion reaction has occurred. The test is also performed in pregnant womenin order to detect a serological conflict between mother and child and be able to react immediately, but this method can also detect unusual antibodies in the mother’s blood, which, passing through the placenta into the baby’s blood, could cause hemolytic disease of the fetus and newborn, or attack red blood cells and cause another disease entity.
Indirect Antiglobulin Test it is also performed in people suffering from autoimmune haemolytic anemia. This means that the body itself produces antibodies against its own white blood cell antigens. Such disease entities include mononucleosis, lupus erythematosus, lymphocytic leukemia and mycoplasmosis.
PTA in pregnancy
Coombs PTA test is performed as soon as possible in the first trimester of pregnancy i if negative re-w 30 weeks pregnant. However, in Rh-negative women, this test is repeated three times during pregnancy because there is a risk of serological conflict. Serological conflict means that the mother is Rh- and the baby is Rh +. If, as a result of the postpartum examination, it turns out that the factors of the mother and the child are different, the woman should be given prophylactic anti-D immunoglobulin within 72 hours, which will eliminate blood cells with the D antigen, which in turn belongs to the child. This prevents a conflict in the future. If the baby’s blood does not enter the mother’s bloodstream, for example by caesarean section, health problems will not arise.
What does the Coombs test look like?
BTA and PTA examinations are the same. Coombs’ test it is simply a blood test taken from the main vein. This test can be performed at any time and you do not need to prepare for it or be on an empty stomach. It is worth informing the attending physician about the medications you are taking, if they could affect the test result.