Explanation

The first action the nurse should take is to assess the surgical incision and drain output. Fever and flank pain after a nephrectomy could indicate a postoperative complication such as an infection, hemorrhage, or urine leak. Inspecting the incision for redness, swelling, or discharge and monitoring the color and amount of drain output can provide valuable diagnostic information.

Administering acetaminophen may treat the fever symptomatically but does not address the underlying cause. Deep breathing and coughing are important for preventing pneumonia but are not the priority in this situation. Increasing the IV fluid rate without assessing the client's fluid status could worsen fluid overload if the client is retaining urine due to a complication.