To establish group affiliation, the AB0 system is used, the essence of which is the presence or absence of special molecules on erythrocytes (red blood cells that carry oxygen) and in the serum - antigens and antibodies, respectively:
The first (0, zero) - only antibodies are present ("a" and "b");
The second (A) - on erythrocytes "A" -antigen and serum "b" -antibodies;
Third (B) - on the contrary, erythrocyte "B" -antigen and serum "a" -antibodies;
Fourth (AB) - there are only antigens ("A" and "B").
As you can see from the above diagram, antigens-antibodies of the same type, for example, "A" and "a" or "B" and "b", cannot be present at the same time, since they are capable of connecting ("sticking") to each other. This is the essence of the clinical significance of the analysis of blood groups, aimed at preventing the transfusion of inappropriate blood-substituting solutions or components. Otherwise, intravascular agglutination will occur - gluing of antigens-antibodies, which will provoke a violation of gas exchange and the development of other pathological processes in the body.
A similar situation arises in the case of the Rh factor, which is a peptide located on the erythrocyte membrane. In those people who do not have this factor (15-20% of the entire population), the immune system does not "know" about its existence. Therefore, when a Rh-positive environment is transfused into a Rh-negative person, an immune reaction is triggered to eliminate the foreign Rh protein by agglutination, and a Rh-conflict arises.
The main reason for the test is the need or high probability of blood transfusion, which happens:
After serious injury associated with blood loss;
In case of gastrointestinal, pulmonary, uterine bleeding;
With severe chronic anemia;
During the preparation of the patient for surgical interventions;
A number of professions associated with a high risk of injury (Ministry of Emergency Situations, military, etc.).
This research is of great importance in obstetrics and neonatology. In the first situation, special attention is paid to pregnant women with negative rhesus to prevent mother-fetus conflict, and in the second - timely diagnosis of hemolytic disease of newborns due to group mother-child incompatibility.
Most often, the indications are determined by the doctor, but everyone can find out their blood group and Rh factor.
