When is it necessary to perform typing and cross-matching of blood?

Performing typing and cross-matching of blood is essential whenever a client is to receive blood products. This process ensures compatibility between the donor’s blood and the recipient’s blood. If blood products are transfused without proper matching, it can lead to serious adverse reactions, including hemolytic transfusion reactions, which can be life-threatening.

Typing refers to determining the ABO and Rh blood group of both the donor and recipient. Cross-matching is the laboratory process that tests how the recipient's blood interacts with the donor's blood. This step is critical because even a small mismatch can induce an immune response, causing the recipient’s body to attack the transfused blood cells.

In contrast, the other scenarios listed do not require typing and cross-matching. Chemotherapy does not involve blood transfusion, elective surgeries may not always require it if a donor blood supply is not anticipated, and vaccines do not involve blood products at all. Thus, the primary focus is on the necessity of matching blood specifically before any transfusion occurs.