Coombstesti

The Coombstesti, commonly known as the Coombs test, is a serologic procedure used to detect antibodies or complement on the surface of red blood cells. It has two main variants: the direct antiglobulin test (DAT) and the indirect antiglobulin test (IAT). The test plays a central role in transfusion medicine, obstetrics, and the diagnosis of certain anemias.

The direct Coombs test examines a patient’s red blood cells directly. A sample of the patient’s red cells is treated with antiglobulin reagent; if the cells agglutinate, the test is positive. A positive DAT indicates that antibodies or complement are bound to the patient’s red cells in vivo. Clinically, a positive result supports autoimmune hemolytic anemia, transfusion reactions, or hemolytic disease of the newborn. False negatives can occur due to low levels of antibody, improper sample handling, or other technical factors; in some cases, elution of bound antibodies is performed to characterize the specificity.

The indirect Coombs test uses the patient’s serum rather than intact cells. The serum is incubated with red cells carrying known antigens, followed by the antiglobulin reagent. Agglutination indicates the presence of antibodies in the serum against red cell antigens. The IAT is used for antibody screening prior to blood transfusion and for prenatal compatibility testing to assess the risk of alloimmune hemolysis in the fetus or newborn.

Overall, the Coombs test remains essential for identifying immune-mediated red cell destruction, ensuring safe transfusion practice, and evaluating neonatal hemolytic disease.