A 62-year-old man undergoes elective abdominal surgery for colon cancer. Current medications are opioid analgesics for postoperative pain control. Approximately 24 hours later, he develops a fever of 38 C. He reports mild shortness of breath. He does not have chest pain, cough, or hemoptysis. Physical examination reveals decreased breath sounds at the lung bases bilaterally without crackles or wheezing. Oxygen sats are 95% on room air. Chest x-ray shows mild bibasilar opacities. Which of the following is the most likely cause of this patient’s fever?
A. Atelectasis
B. Postoperative pneumonia
C. Pulmonary embolism
D. Surgical site infection
E. Urinary tract infection
