ABO incompatibility

ABO incompatibility occurs when a person's blood type doesn't match the blood type of a blood transfusion they receive. The human blood types—A, B, AB, and O—are determined by specific molecules called antigens on red blood cells. If someone receives blood with incompatible antigens, their immune system may recognize these as foreign and produce antibodies against them. This immune response can cause a serious reaction, damaging red blood cells and leading to complications like anemia or more severe issues. Proper blood matching ensures that transfusions are safe by preventing these immune reactions.