Direct antiglobulin test (DAT)

What is an antiglobulin test (Coombs reaction)?

Direct Coombs reaction (otherwise known as direct antiglobulin test) is a test thatós rapid detection of antibodies found in red blood cells thatóve the ability to bind to erythrocyteós antigens, which can result in their accelerated destruction leading to hemolytic anemia (anemia). This diagnostic test is most often used in the rapid diagnosis of serological conflict occurring in a newborn shortly after birth.

When should an antiglobulin test (Coombs reaction) be performed?

By performing a direct Coombs' reaction, it is possible to quickly confirm or rule out the presence of immune-mediated hemolytic anemia in a given patient.

Anemia

Anemia, otherwise known as anemia, is a medical condition in the course of which there are too few red blood cells or too little hemoglobin in the body. As a consequence of this, the blood is unable to carry oxygen to the body's tissues with adequate efficiency, which causes disease symptoms. Depending on the severity of the anemia, the patient's age and otherófactors, they can be mild or pose a serious threat to the patient's health and life.

Hemolytic anemia results from the premature breakdown of red blood cells, so that the bone marrow is unable to replenish lost erythrocytesófast enough, leading to the development of anemia. This type of anemia can have many causes, such as genetic (sickle cell anemia resulting from an abnormal structure of the erythrocyteós cell membranes), parasite-induced (breakdown of red blood cells as a result of a pathogenic protozoan in the course of malaria) or immunological, where erythrocytes are destroyed by an abnormal reaction of the immune system. It can be triggered by faulty recognition of one's own cellsórek as foreign (weóre talking about an autoimmune disease) or as a result of blood contact with foreign antibodies.

One of the most common cases of such a reaction is hemolytic disease of the newborn, where the baby's blood comes into contact with the mother's blood during delivery. If there is an incompatibility between the two in terms of blood type (most often Rh group), the mother's antigens can begin the process of destroying the baby's blood cells atós birth.

Who should take an antiglobulin test?

Serological conflicts between a pregnant mother and her child may be suspected when there is a risk of Rh-group incompatibility. To determine these, it is necessary to know the blood groups of both the mother and the father. If the father is Rh+ and the mother Rh-, there is a risk that the baby will also be Rh+ blood type, which can lead to the development of a serological conflict. The most effective would be to determine the baby's blood type through prenatal testing, but invasive prenatal testing that would allow this carries the risk of serious complications of the course of the pregnancy, including miscarriage.

It is also possible to determine, among other things, the blood type on the basis of non-invasive prenatal tests that use free fetal DNA present in the mother's blood during pregnancy. However, if these tests are not performed at the time blood is drawn from the mother to determine alloantibodies present in her plasma, depending on how high their concentrations reach, the risk of hemolytic disease of the newborn is assessed and possible preventive treatment is implemented to inactivate these antibodies until delivery.

As it is difficult to assess the subjective symptoms present in the newborn, the direct Coombs reaction test is performed if there are indications of hemolytic anemia in blood tests.

Antiglobulin test results

A positive result of the direct Coombs test, i.e. the presence of agglutination of blood cells, indicates the presence in the blood of a newborn baby of antibodies that are responsible for destroying its erythrocytes. The baby's condition should be carefully monitored atótion and, if necessary, treatment should be initiated, which&oac;re often based primarily on blood transfusions.