Final answer:
To protect against blood-group incompatibility during a transfusion, confirm both the unit of blood and patient's blood types, perform a cross-match test, closely monitor the patient during transfusion, and stop immediately if any signs of a reaction occur. Type O blood is used as a universal donor in emergencies where there isn't time to determine blood type, although a proper match is always preferable.
Step-by-step explanation:
To protect a patient against the possibility of blood-group incompatibility during a transfusion, several procedures must be followed. Firstly, pretransfusion blood testing is necessary, which includes both testing the unit of blood with commercially prepared antibodies against the A, B, and Rh antigens to confirm the listed blood type, and also confirming the patient's blood type with the same process. Before transfusion, a cross-match is performed to check for compatibility, where a small sample of the donor red blood cells is mixed with the patient's serum, observing for agglutination, which indicates incompatibility.
During the transfusion, it is imperative to monitor the patient closely for any signs of a reaction. If there is any sign of a transfusion reaction, such as discomfort, fever, chills, or dark urine, the transfusion must be stopped immediately, and appropriate steps to manage the adverse reaction should be taken. This highlights the importance of close observation and prompt intervention in the case of adverse reactions. In certain emergency scenarios where blood type cannot be determined in time, type O blood may be used as it is considered a universal donor in life-threatening situations, although this is less ideal than a proper match.