Final answer:
Before beginning a PRBCs transfusion, pretransfusion blood testing is essential to check donor and recipient blood type compatibility, followed by a cross-matching procedure, and an antibody screening test to detect any potentially harmful antibodies. Type O blood may be used in life-threatening emergencies without these tests.
Step-by-step explanation:
Before a packed red blood cells (PRBCs) transfusion can be administered, certain critical steps must be performed to ensure patient safety and compatibility of the blood type. To begin with, comprehensive pretransfusion blood testing is mandatory. This includes using commercially prepared antibodies to validate the ABO and Rh blood types of both the donor unit and the recipient. This is crucial in preventing adverse reactions which could lead to hemolytic transfusion reactions (HTRs).
Upon confirmation of blood types, a cross-matching procedure follows, where a sample of donor red blood cells is mixed with the recipient's serum. The presence of hemagglutination indicates incompatibility, necessitating further investigation with Coombs' reagent. For emergencies, such as life-threatening hemorrhages, type O blood, commonly known as the 'universal donor', maybe transfused when there is no time for these compatibility tests.
Additionally, an antibody screening test is performed to detect any antibodies that might react with antigens outside of the ABO or Rh systems, which are not identified by the primary blood typing tests. Knowing the recipient's exact blood type and the absence of incompatible antibodies help to prevent severe transfusion reactions.