Correct understanding of blood type and blood transfusion principles

In 1901, Landsteiner discovered the phenomenon: this person's serum causes the other person's red blood cell to agglutinate and vice versa. The antigen A and antigen B, antibody a (anti A) and antibody b (anti B) were found. So many antigens have been found so far. Based on the presence of antigens on the surface of red blood cells, people are divided into the blood group systems ABO, Rh, Duffy, Kids, Lewis, Kells, P, MNSs . Of these, the system ABO and Rh blood groups are more interested because it plays an important role in blood transfusion.

Each blood group has its own characteristics, the structure of blood vessels can be broken if improperly transmitted blood group is compatible. So it is important to know what blood type you belong to and its characteristics.

Why are there different blood groups?

Scientists believe that human ancestors adapt to how infectious diseases cause different blood groups. For example, malaria seems to be the main cause of O blood, which is more common in Africa and parts of the world that have suffered from malaria. In many cases malaria-infected cells cannot attack cells of blood type O or B-type blood cells. As a result, people with blood type O have better resistance to malaria. .

How are blood groups classified?

Human blood is divided into several groups based on a number of specific carbohydrates and proteins on red blood cells. There are about 46 different groups, but the main groups are O, A, B and Rhesus (Rh). The blood of each group may have antibodies against the other groups. Therefore, when other blood transfusions are added, the recipient's antibodies can destroy the blood that harms the body.

Antigen and antibody

In general, antigens are "any substance that the immune system can meet " . The membrane of each red blood cell contains millions of antigens that are ignored by the immune system, although the immune system will attack any red blood cells that contain antigens other than their antigenic cells. .

Antibodies are important molecules that our immune system produces to help protect the body against external invaders such as bacteria and viruses . These bacteria and viruses can also be formed to meet different blood groups.

There are about 46 different groups, but the main groups are O, A, B and Rhesus (Rh).

Rh factor

Most people (about 85% of humans) have a special protein on their blood cells, called the Rh factor. These are called Rh + (Rh positive blood group) . Those who lack Rh factor, are called Rh- (have a Rh negative blood group).

Pregnant women need Rh factor test in the blood, through which to screen and detect compatibility in the mother and baby body. If the mother has Rh- and the baby is Rh +, the mother's body will react to the baby's blood as an external substance. Your body will produce antibodies (proteins) against your baby's Rh + blood. Rh incompatibility can cause problems in the mother's subsequent pregnancy, when Rh antibodies can cross the placenta and attack the baby's red blood cells, resulting in anemia. blood in the baby, meaning that red blood cells are destroyed.

Fortunately, if these incompatibilities are detected early, doctors will apply prenatal treatments to help prevent any problems before they arise.

What blood groups are there?

Blood type A

Blood type A is characterized by the presence of antigen A on red blood cells, and antibody B in plasma.

People with type A blood can safely donate blood to other people with the same blood type A, or those with type AB blood. In addition, people with blood type A can also receive blood transfusions of people with O.

Blood group B

This blood type is relatively rare (only behind AB). It contains B antigens on red blood cells, and antibody A (to attack antigen A) in plasma.

People with blood type B can safely donate blood to other people of the same blood type B, or to people with type AB blood. In addition, people with B blood can safely receive blood transfusions from people with O.

Blood type O is the most common blood type.

Blood type AB

This blood type is not common. Blood type AB is characterized by having both antigens A and B on red blood cells, and without antibodies in plasma.

People with blood type AB can accept blood from anyone. However, because of the presence of both antigens on type AB red blood cells, people with AB blood can only donate blood to people with the same blood type AB with them.

Blood type O

Blood type O is the most common blood type. Blood type O has no antigen A and B antigen in red blood cells, but both antibodies A and B in plasma. As a result, people with blood type O can only receive blood transfusions from people with the same blood type O, because its plasma antibodies will attack other types. However, people with O blood can donate blood to all other blood groups, because blood type O has absolutely no hostile antigens in the immune system. Therefore, people with type O blood are called "global donors".

What if you get the wrong blood type?

Very bad. Acute hemolysis can occur within 24 hours of transfusion and usually occurs during blood transfusions. Patients can feel these reactions. They may complain about hot sensations at the transfusion site, a feeling of chills, fever, and pain in the back, flanks . The cutting reactions involve severing most vascular canopies; Red blood cells of infused blood are destroyed by the antibodies of the recipient while they still have internal blood vessels. Simultaneous reactions can be shocking, large amounts of tissue produced by RBC (red blood cells) rupture, so the blood clotting capacity cannot be controlled.

Principle of blood transfusion

To ensure safety in blood transfusion, the following blood transfusion principles must be complied with:

1. The same blood group must be transmitted to avoid the antigen and the corresponding antibodies, causing the red blood cells to bind together (agglutination).
2. In addition to determining the blood type of donor and recipient, cross-reactivity is required: Mix the red blood cells of the donor with the recipient's serum and vice versa, mix the recipient's red blood cells with the donor's serum.If there is no red cell agglutination, then that blood is passed on to the recipient.
3. If blood transfusions fail, it can cause serious complications for blood recipients, even causing death after a few days.

However, in emergency cases where blood transfusions are required without blood in the same group, then another group must be forced to comply with the minimum rule: "Red blood cells should not be agglutinated with serum. recipient " , only a small amount of blood (250ml) is transmitted and very slow transmission. Thus, blood transfusion diagram can be as follows:

Blood transfusion diagram.