In medical practice, quite often there are cases when patients lose a large amount of blood. For this reason, they need to transfuse it from another person - the donor. This process is also called transfusion. Before transfusion, a large number of tests are carried out. It is necessary to choose the right donor so that their blood is compatible. In case of complications, violation of this rule often leads to death. At the moment, it is known that a universal donor is a person who has the first blood group. But many doctors are of the opinion that this nuance is conditional. And there is no person in this world whose connective tissue of the liquid type is suitable for absolutely everyone.
What is a blood type
The group of blood is the set of antigenic properties of red blood cells that a person has. A similar classification was introduced in the 20th century. At the same time, the concept of incompatibility appeared. Due to this, the number of people who successfully underwent a blood transfusion procedure has increased significantly. In practice, there are four types. We will briefly consider each of them.
First blood type
Zero or the first blood group does not have antigens. It contains antibodies alpha and beta. It does not have foreign elements, therefore people with blood type 0 (I) are called universal donors. It can be transfused with people with other blood types.
Second blood type
The second group has type A antigen and antibodies to agglutinogen B. It cannot be transfused with all patients. It is allowed to do this only to those patients who do not have antigen B, that is, patients with the first or second group.
Third blood type
The third group has antibodies to agglutinogen A and type B antigen. This blood can only be transfused to the owners of the first and third groups. That is, it is suitable for patients who do not have antigen A.
Fourth blood type
The fourth group has antigens of both types, but its composition does not include antibodies. Holders of this group can transfer part of their blood only to owners of the same type. It has already been said above that a universal donor is a person with a blood group of 0 (I). What about the recipient (the patient who takes it)? Those who have a fourth blood group can take any, that is, they are universal. This is due to the fact that they do not have antibodies.
Features of transfusion
If antigens of that group that are incompatible get into the human body, then foreign red blood cells will gradually stick together. This will lead to circulatory disorders. Oxygen in this situation abruptly ceases to flow to organs and all tissues. Blood in the body begins to coagulate. And if you do not start treatment on time, this will lead to rather serious consequences. That's why before completing the procedure, it is necessary to conduct tests for compatibility of all factors.
In addition to the blood type, the Rh factor must be considered before transfusion. What is it? It is a protein that is part of red blood cells. If a person has a positive indicator, then he has the D antigen in his body. On a letter, this is indicated as follows: Rh +. Accordingly, Rh- is used to mark the negative Rh factor. As already understood, this means the absence of group D antigens in the human body.
The difference between the blood type and the Rh factor is that the latter plays a role only during transfusion and during pregnancy. Often, a mother with D antigen is not able to bear a child who does not have one, and vice versa.
The concept of universality
During transfusion of red blood cells, people with a blood type of the first with a negative Rhesus are called universal donors. Patients with the fourth type and the positive presence of D antigen are universal recipients.
Such statements are only suitable if a person needs to receive a reaction of antigens A and B during transfusion of blood cells. Often, such patients are sensitive to foreign cells of a positive rhesus. If a person has the HH system - the Bombay phenotype, then such a rule does not apply to him. Such people may receive blood from HH donors. This is due to the fact that in red blood cells they have antibodies specifically against N.
Universal donors cannot be those who have antigens A, B or any other atypical elements. Their reactions, as a rule, are not often taken into account. The reason is that during transfusion, a very small amount of plasma is sometimes transported, in which foreign particles are directly located.
Finally
In practice, most often a person receives blood from the same group and the same Rh factor that he has. The universal option is resorted to only when the risk is really justified. Indeed, even in this case, an unforeseen complication can occur, which will entail cardiac arrest. If there is no necessary blood, and there is no way to wait, then doctors use a universal group.