A nurse is caring for a client who is 2 days postoperative. Which of the following findings should the nurse identify as an indication of postoperative infection?

Edema to the area around the incision site

Serous drainage in the closed suction collection device

Urine output is 40 mL/hr

WBC count 8, 000/mm3 (5,000 to 10,000 mm3)