ABO And Rh(D) | Blood Group and Rh Factor Determination

Blood group (ABO) and Rh(D) factor determination – is one of the most important immunological blood tests used to determine a patient's blood group according to the ABO system and the presence of the Rh(D) antigen. The ABO system is clinically significant due to the strongly expressed natural antibodies (anti-A, anti-B) that can cause dangerous blood transfusion reactions. According to this system, people are assigned to one of four blood groups: 0 (I), A (II), B (III), or AB (IV), depending on the presence of A and B antigens on the surface of erythrocytes and the presence of corresponding antibodies in the blood plasma.

The Rh(D) system is the second most important blood group system. It is based on the presence or absence of the D antigen on the surface of erythrocytes. Individuals with the D antigen are considered Rh positive (RhD+), and those without it are Rh negative (RhD−). The Rh(D) status is especially important during pregnancy (it can be associated with the development of hemolytic disease of the newborn) and in blood transfusion practice to avoid immune complications.

Test principle: The test is performed using a serological method, where the patient's erythrocytes are mixed with standard antibody reagents (anti-A, anti-B, anti-D). Observation of agglutination (cell clumping) allows the determination of the blood group and Rh(D) status.

Recommendations:

• It is recommended before any surgical interventions, blood transfusions, when planning or monitoring pregnancy, and in cases of donation.
• The test is performed once in a lifetime but can be repeated if there are doubts about group accuracy or if additional confirmation is needed.
• The blood group result does not change throughout life, but in certain cases (e.g., after transplantation, treatment of oncohematological diseases), temporarily atypical results may occur.
• No special preparation is needed for the test, but it is recommended to inform the doctor about previous transfusions, pregnancies, or immune reactions.