Knowing your blood type is crucial in two key scenarios: during pregnancy, to confirm compatibility between the mother and baby, and before surgery as part of preoperative assessments. In cases requiring a transfusion, only compatible blood can be used. Your doctor will provide a prescription for the test, ensuring reimbursement. Blood donors also undergo typing to verify compatibility.
To establish your blood type and create a blood type card, labs take two blood samples at different times. This can be done in a medical laboratory, hospital, or similar facility. No fasting is required for this simple blood draw.
The four primary blood types—A, B, AB, and O—reflect the presence or absence of specific antigens and antibodies on red blood cells. Group A has only A antigens, group B has only B antigens, group AB has both, and group O has neither antigen but two types of antibodies. The Rh factor adds another layer: Rh-positive if present, Rh-negative if absent. Your blood type is inherited from your parents—for example, if both are A, the child is A; if one is A and the other B, the child is AB; if one is A and the other O, the child is A; if both are O, the child is O.
