A 62-year-old male undergoes an elective open cholecystectomy. Twelve hours post-operatively, his temperature is 100.8°F (38.2°C). His lung sounds are diminished at the bases, and he has a non-productive cough. Surgical site appears clean and dry. What is the most likely cause of his fever?
✓ Correct Answer: Option C
Atelectasis is a common cause of fever in the first 24-48 hours post-surgery, often presenting with low-grade fever, diminished breath sounds, and a non-productive cough due to inadequate lung expansion. Infections typically present later.