Quick answerStop the transfusion and maintain the intravenous line with saline.
Why this is correctA febrile response can be benign or the first sign of a hemolytic reaction, and they cannot be separated at the bedside in the first minutes. Stopping limits how much incompatible blood is given while the saline keeps a route available for treatment.
Easy analogy or mental pictureStopping the infusion is like closing a valve before inspecting the pipe. The image conveys containment and does not mean the intravenous access is removed.
Memory hookNew fever during blood: stop the unit, keep the line.NCLEX decision ruleFor any suspected transfusion reaction, stop the blood, keep the line open with saline, then assess and notify. Investigation and treatment follow that sequence rather than replace it.
Why the other choices are wrongUrine testing, antipyretics, and returning the bag are all part of transfusion reaction management, but each assumes the unit is already stopped.