Which test performed on donor packed cells helps prevent immediate hemolytic transfusion reactions?

The test that is performed on donor packed cells to help prevent immediate hemolytic transfusion reactions is the ABO typing test. This test identifies the blood group of the donor's packed cells and ensures proper compatibility with the recipient's blood type.

Immediate hemolytic transfusion reactions typically occur when there is a major incompatibility between the donor's and recipient's blood types, especially in the ABO system. If a recipient receives incompatible blood, their immune system can rapidly attack the transfused red blood cells, leading to potentially life-threatening complications. By accurately determining the ABO blood group of donor cells, healthcare professionals can ensure that the transfusion is safe, thereby minimizing the risk of such reactions.

The other tests mentioned, while important for different reasons, do not specifically address the immediate prevention of hemolytic reactions in the context of ABO incompatibility.