To determine, to know the blood group of a person, the technique is now well established and commonly practiced by caregivers. For this purpose two blood samples are needed: a sample and a counter-sample.
The sample is divided into three portions to which a test serum is added respectively:
a serum No. 1 containing the anti-A antibodies.
a serum No. 2 containing the anti-B antibodies.
a serum No. 3 containing antibodies against both antigens (anti-AB antibodies) (left in the table).
The blood group can be determined by observing which mixtures of blood and test serum are agglomerating.
In the case of blood group A, for example, the blood clumps when it comes into contact with anti-A and anti-AB antibodies - which are contained in test serum # 1 and # 3 in our example.
The counter-sample (right in the table) of blood is also divided into three portions. But this time, red blood cells of the blood groups A, B and O are added. As for the sample, we observe which of the three mixtures agglutinate, which again depends on the antibodies contained in the blood. agglutination when the analyzed blood belongs to the same blood group as the "control" blood with which it was brought into contact.
If the tests are correctly performed, the results of the sample and the counter-sample are identical.
Here is a schematic representation of blood group determination:
Diagram: determination of the blood group
In the case of pregnancy
An ABO incompatibility between mother and child is frequently observed when the mother is of the blood group O and the child of the blood group A.
Unlike rhesus incompatibility, this incompatibility does not affect the health of the fetus before birth. After birth, however, there is a yellowing of the skin which intensifies rapidly. This jaundice (or jaundice ) can be easily treated with phototherapy .
In this light treatment, we use the blue zone of the light spectrum, thus the light of a wavelength between 420 and 480 nanometers (nm), to eliminate the bilirubin (a yellow pigment) contained in the skin of the baby.
The baby is then exposed naked to this blue light, the eyes protected by a special mask to prevent damage to the retina.
In rare cases, when light therapy is not enough to lower the level of bilirubin, an exchange transfusion (change of the baby's blood) may be necessary.