Blood group/Rh factor
Why this test?
To determine a possible rhesus-conflict between the mother and the fetus.
If its high probability is determined, the woman is prescribed injections of serum containing anti-Rhesus immunoglobulin, which binds to the erythrocytes of the fetus and «hides» them from the mother's immune system, which prevents the production of antibodies to the erythrocytes of the fetus.
To select a donor for a safe blood transfusion. It is important to make sure that the donor blood is compatible with the blood of the recipient. If the donor blood or its components contain antibodies to the protein contained on the recipient's erythrocytes, a severe transfusion reaction caused by the destruction of erythrocytes in the vascular bed may develop.
Currently, only blood that matches the group and Rh factor of the donor and the recipient is allowed to be transfused.
In what cases is it prescribed?
- During pregnancy, to confirm the blood group, Rh factor and anti-Rhes antibodies of the woman.
- This information is of great importance during pregnancy.
- When donating blood.
- Most often, blood transfusion is necessary for:
- bleeding that occurred in the patient during or after surgery,
- severe injuries,
- significant blood loss,
- oncological diseases and side effects of chemotherapy,
- blood coagulation disorders, in particular hemophilia.
AVO blood group is a system that reflects the presence or absence of antigens on the surface of erythrocytes and antibodies in blood plasma. ABO (read as «a-be-zero») is the most common system of blood groups in Ukraine. Erythrocytes carry signal molecules - antigens - agglutinogens on their surface. The two main antigens embedded in the erythrocyte molecule are A and B.
Blood groups are determined based on the presence or absence of these antigens. The blood of people who have antigen A on their erythrocytes belongs to the second group - A (II), the blood of those who have antigen B on their erythrocytes belongs to the third group - B (III). If both antigens A and antigens B are present on erythrocytes, this is the fourth group - AB (IV). It also happens that none of these antigens are detected on erythrocytes in the blood - then this is the first group - O (I).
Normally, the body produces antibodies against those antigens (A or B) that are not present on erythrocytes - these are agglutinins found in blood plasma. That is, in people with the second blood group - A (II) - antigens A are present on erythrocytes, and antibodies to antigens B are present in the plasma - they are designated as anti-B (beta-agglutinin).
Since antigens of the same name (agglutinogens) on the surface of erythrocytes and agglutinins in plasma (A and alpha, B and beta) react with each other and lead to «gluing» of erythrocytes, they cannot be contained in the blood of one person.
The discovery of the ABO group system made it possible to understand why blood transfusions were sometimes successful and sometimes caused severe complications. The concept of blood group compatibility was formulated. For example, if a person with the second blood group - A (II), which contains antibodies to antigen B, is transfused with the third blood group - B (III), a reaction between the antigens and antibodies will occur, which will lead to sticking and destruction of erythrocytes and can have serious consequences up to a fatal outcome.
Therefore, the blood groups during transfusion must be compatible. The blood group is determined by the presence or absence of erythrocyte adhesion using serums containing standard antigens and antibodies. In blood transfusion centers, bags with blood or its components received from donors are marked «O (I)», «A (II)», «B (III)» or «AB (IV)», which allows quickly find blood of the right group when it is needed. Rhesus factor is a protein found on the surface of red blood cells in some people. The blood of those who have it is called Rh-positive, and those who do not have it - Rh-negative.
The presence or absence of this protein is an individual feature, not a pathology. A positive Rh factor is found in 85% of people, respectively, a negative one - in 15%. The Rhesus factor is of particular importance during pregnancy.
If the mother is positive Rh, then her blood will be compatible with the blood of the child in any case, if it is negative, there are possible options: in the case when the father of the child also has a negative Rh factor, the blood of the mother will be compatible with the blood the fetus, because the child also inherits a negative Rh factor, when the father has a positive Rh factor, and the mother has a negative one, there is a 50% probability that the blood of the mother and the child may not be compatible - a Rhesus conflict, which threatens with complications. It happens as follows: when the blood of the fetus enters the bloodstream of the mother, antibodies to its positive Rhesus in her body begin to be produced, since the proteins on the molecules of erythrocytes are perceived by the mother's body as something foreign. This is not dangerous for a woman, but antibodies penetrate the bloodstream of the fetus through the placenta, which threatens it with negative consequences: the antibodies «stick» to the erythrocytes of the fetus and can cause them to stick together. This process is called hemolysis.
Hemolysis during pregnancy can lead to disorders of fetal development and in some cases to miscarriage, and after birth to the so-called hemolytic jaundice of newborns, in which a significant number of erythrocytes are destroyed in the baby's blood. At the same time, the newborn's skin turns yellow, as the products of the breakdown of erythrocytes are painted in yellow. Most often, the brain is affected, dropsy may develop. In severe cases, the baby needs a blood transfusion.