Which of the following can contribute to adverse reactions during a transfusion?

Incompatibility between the donor's and recipient's blood types is a key factor that can lead to adverse reactions during a transfusion. When blood from a donor is transfused into a recipient, it is crucial that their blood types are compatible. This means matching the ABO blood group systems and the Rh factor. If incompatible blood is transfused, the recipient's immune system may recognize the foreign blood cells as a threat and mount an immune response against them, which can result in serious and potentially life-threatening complications.

Understanding blood compatibility is critical in transfusion medicine. For instance, if a person with type A blood receives type B blood, their body will react to the B antigens found on the surface of the donor red blood cells. This immune response can lead to hemolysis, where the recipient's body destroys the transfused red blood cells, resulting in symptoms ranging from fever and chills to shock and organ failure.

The other options, while important for safe transfusion practices, do not directly cause adverse reactions. Proper patient identification and the use of sterile techniques are essential for ensuring that the right patient receives the correct blood product and for preventing infections, respectively. Consistent monitoring of vital signs is crucial for identifying any reactions as they occur and managing them