A 60-year-old female undergoes an elective total knee arthroplasty. On post-operative day 3, she develops a fever of 101.5°F (38.6°C). Her physical exam is unremarkable except for mild incisional tenderness. She has no cough or dysuria. What is the most appropriate initial diagnostic step in evaluating her fever?
✓ Correct Answer: Option C
Post-operative fever on day 3 warrants investigation. Common causes include urinary tract infection, pneumonia, and wound infection. A chest X-ray, urinalysis, and blood cultures are appropriate initial steps to rule out these possibilities.