Blood Transfusion: Update on Irregular Agglutinin Research
Irregular agglutinin testing (also called irregular anti-erythrocyte antibody testing) allows the identification of antibodies directed against antigens that are not present on the surface of a patient’s red blood cells.
This research is systematic before any transfusion and during pregnancy. Here is an update.
Search for Irregular Agglutinins: definition
Any substance foreign to the organism (also called an antigen) provokes the production of antibodies directed against it. The term agglutinins is synonymous with antibodies.
Agglutinins are called irregular because they are synthesized to foreign red blood cells in the bloodstream. These:
– come from a transfusion;
– are the result of an autoimmune phenomenon (linked to a dysfunction of the immune system);
– or appear during pregnancy when the child’s red blood cells can pass into the maternal circulation.
The potential seriousness of these antibodies is related to the possibility of anemia by agglutination and the destruction of red blood cells.
A physician must prescribe the search for irregular agglutinins. It is not necessary to fast to perform this test:
A blood tube is taken from the elbow after placing a tourniquet on the arm.
– The results are usually available within 24 hours of the sample being taken.
– This test involves reacting the patient’s serum with several known red blood cells (red blood cell panel).
Testing for irregular agglutinins is critical in the following situations:
– before any red blood cell transfusion, to avoid a transfusion accident;
– during the premarital examination (which is no longer mandatory since 2008);
During pregnancy, the presence of these antibodies can destroy the fetus’s red blood cells and cause hemolytic disease in the newborn.
In the case of a blood transfusion, in the event of positive results indicating the presence of irregular agglutinins, the physician at the transfusion center takes care to select the blood bags with care, thus avoiding any risk of transfusion accident.
Immunization against the D antigen (Rhesus system)
If the pregnant woman is Rhesus negative (which means that the mother’s red blood cells do not carry the D antigen on their surface) and the future father of the child is Rhesus positive (which means that his red blood cells carry the D antigen on their surface), 2 cases can be observed:
– If the child is Rhesus-negative, the mother’s immune system will not produce antibodies against the D antigen because it is not present on the surface of the child’s red blood cells. There is no risk in this case.
– However, if the child is Rhesus positive, the child’s red blood cells carrying the D antigen can circulate in the mother’s blood (during pregnancy or delivery). The mother’s immune system then synthesizes antibodies to the D antigen. During a future pregnancy, if the child is Rhesus positive, its red blood cells are recognized by the mother’s antibodies directed against the D antigen, leading to their destruction and the possible death of the fetus.
It is imperative to inject the mother with anti-D antibodies during the 28th week of the first pregnancy or within 72 hours after the first delivery to prevent her immune system from making anti-D antibodies to avoid this accident.
The injection of these anti-D antibodies is also necessary for any Rhesus-negative woman after a miscarriage, ectopic pregnancy, or abortion to prevent the formation of antibodies directed against the D antigen, which could be dangerous in a new pregnancy.
Hope you have liked this post. This post is incomplete without your participation. Remember to share your opinion in the comments below.