What is the appropriate first step for a technician when a patient shows signs of a delayed transfusion reaction?

In the scenario of a delayed transfusion reaction, the appropriate first step is to identify the antibody in the serum and eluate from the posttransfusion sample. This step is crucial because it helps determine whether the transfusion reaction is caused by the development of new antibodies against antigens present on the transfused red blood cells.

When a patient exhibits signs of a delayed reaction, it typically implies the formation of antibodies that occur days to weeks post-transfusion. By performing an antibody identification on the serum from the patient and executing an eluate from the posttransfusion sample, the technician can identify any new antibodies that may have emerged as a result of the transfusion. This leads to a better understanding of the underlying issue and informs further investigation and management for the patient.

The other options, while they may seem relevant, are not the most immediate or appropriate steps for a technician facing a delayed transfusion reaction. For instance, retyping samples or repeating antibody screens are important processes in the investigation but are secondary to directly identifying any newly formed antibodies which is essential to address the immediate concerns of the patient’s reaction.