Final answer:
All of the following steps should be taken in the immediate investigation of a potential hemolytic transfusion reaction except for a gram stain of the patient's plasma.
Step-by-step explanation:
In the immediate investigation of a potential hemolytic transfusion reaction, all of the following steps should be taken except for A. A gram stain of the patient's plasma. The other steps that should be taken include: B. Rechecking patient and unit identification, C. Stopping the transfusion immediately, and D. Notifying the blood bank and healthcare provider. A gram stain is not typically performed in the investigation of a potential hemolytic transfusion reaction.