Patient Care Technician (PCT) AAH Practice Exam

Which blood type is considered to be the universal donor?

1. A

2. B

3. O

4. AB

The correct answer is: O

The blood type that is considered the universal donor is O. This classification stems from the fact that type O blood has no antigens on the surface of its red blood cells. In contrast, other blood types have specific antigens; for instance, type A has A antigens, type B has B antigens, and type AB has both A and B antigens. When a person receives a blood transfusion, it's crucial to match the donor's and recipient's blood types to avoid an immune reaction. If someone with blood type O donates to a recipient with any other blood type, there are no A or B antigens present that could cause a reaction. This makes O type blood safe for transfusions to any recipient, leading to its classification as the universal donor. On the other hand, people with AB blood type, which has both A and B antigens, can receive blood from all types; however, they cannot donate to everyone, making them a universal recipient rather than a universal donor.