Blood Transfusion Guide
A blood transfusion moves red cells, plasma, or platelets from a donor to a patient who needs them. It is safe only when the donor blood matches the recipient's type.
How a Transfusion Works
1. Determine the patient's blood type
A sample is tested with anti-A, anti-B, and anti-Rh reagents to find the ABO group and Rh status.
2. Select compatible donor blood
The donor unit is chosen so the recipient's antibodies will not attack the donor red cells. See the compatibility chart.
3. Cross-match
Donor and recipient blood are mixed in the lab to confirm there is no reaction before transfusing.
4. Transfuse and monitor
The blood is given slowly while staff watch for any sign of a reaction.
What Causes a Transfusion Reaction
Every person's plasma carries antibodies against the ABO antigens they do not have. If a patient receives red cells carrying an antigen their antibodies recognize as foreign, the antibodies bind the donor cells and make them clump together (agglutination) and break apart (hemolysis). This is a hemolytic transfusion reaction, and it can be fatal. Correct blood typing is what prevents it.
Key Safety Rules
- O− red cells are safe for any recipient (universal donor), used in emergencies before typing is done.
- AB+ patients can receive red cells from any type (universal recipient).
- Rh-negative patients should receive Rh-negative blood whenever possible.
- Always confirm patient identity and unit label before transfusing.
Practice It Yourself
The Blood Typing Game lets you test a patient, read the agglutination pattern, choose a compatible donor unit, and perform the transfusion, the same steps used in a real lab. Read the fundamentals first in Blood Types Explained.
This guide is for education only and is not medical advice. Real transfusions follow strict clinical protocols.