The blood group, as well as the Rh factor, are unchanged genetic traits that form in the womb of the mother. Neither during fetal development, nor during a life, it can not change. However, you can often hear from people that they had one group, but after a while it became different. This is especially true of women during pregnancy, as well as people who have suffered some diseases.
Doctors give this simple explanation: the wrong result in laboratory studies. It is believed that mistakes were often made earlier in determining the group affiliation. In our time, the reagents have become more qualitative, and the results are more accurate.
What is the blood type?
Today in the world the classification according to the AB0 system is accepted, according to which there are four groups:
- 0( first) - there are no antigens on the surface of red cells, the antibodies α( anti-A) and β( anti-B) are present in the plasma;
- A( second) - red blood cells contain anti-A on the membrane, there are antibodies β( anti-B) in the plasma;
- B( third) - on the surface of red blood cells is anti-B, in plasma - antibodies α( anti-A);
- AB( fourth) - because there is antigen A and B on the erythrocyte shell, there are no antibodies in the blood, either α or β.
Each agglutinogen has its own antibody( agglutinin), which will lead to the gluing of red blood cells.
Thus, there are a lot of combinations. Today, two most important classifications have been adopted. This system AB0, according to which group affiliation is dependent on combinations of antigenic components on erythrocytes. Rh system( Rh factor), according to which the blood differs due to the presence or absence of a special protein on the envelope of red cells and can be Rh-positive or negative.
Why can it change?
The group is determined by gluing together the red blood cells. To do this, serums containing antibodies( agglutinins) α, β, α and β are dripped onto a special plate. Then a drop of blood is added to each, while the serum should be about ten times larger. After that, observe under the microscope the reaction of agglutination( clumping) of erythrocytes within five minutes. Based on the results of this reaction, the type of blood is determined:
- if no gluing has occurred in any serum, it is I;
- if the reaction is positive with sera containing the α and α + β antibodies, then this is II;
- if agglutination occurred in the serum with antibodies β and α + β, then this is III;
- if all sera produced positive results, it means that the blood contains both antibodies and belongs to the IV type.
Blood group definition
Why can the group change? For this, it is necessary that the antigens of erythrocytes cease to be produced or their production is greatly weakened. There is an opinion that this can occur with infectious diseases, pregnancy, with tumors, some diseases associated with increased production of red cells. In this regard, in laboratory studies, antibodies can not detect such a small amount of antigens or the reaction is so weak that it is not visible. Thus, under certain conditions, a temporary change in the results of the analyzes is possible, but not a change in group affiliation.
It can be concluded that the group in a person will not become another with age or other reasons. Moreover, the combination of antigens, which is already in the first stage of intrauterine development, can not change during pregnancy or after childbirth.
If the analysis shows that the blood has changed, it's probably worth talking about a mistake during the lab test. In addition, the result of the study may be associated with weakly expressed antigens. In this case, usually re-assays are made using other reagents. Thus, it is worthwhile to clarify once again that the blood group was not changed, but the results of the analyzes.