A 60-year-old man with cirrhosis and a remote history of colon cancer, for which he had undergone a hemicolectomy, presented to the emergency department with a fever. He reported no diarrhea, vomiting, or abdominal pain. His temperature was 38.5°C. There was no tenderness to palpation across his abdomen. Laboratory studies revealed a white-cell count of 12,300 per cubic millimeter (normal range, 3600 to 11,000) and a total bilirubin level of 2.0 mg per deciliter (34.2 μmol per liter) (normal range, 0.2 to 1.3 mg per deciliter [3.4 to 22.2 μmol per liter]), although his baseline total bilirubin level was 2.0 mg per deciliter owing to his liver disease. The aminotransferase levels, alkaline phosphatase levels, and urinalysis results were within the normal range. Two sets of blood cultures obtained on admission grew Escherichia coli. Computed tomography, which was performed to determine possible intraabdominal sources of infection, revealed no abscess, ascites, or colitis but did show multiple small, round, calcified gallstones (Panels A and B). Although no definitive source of the bacteremia was found, the patient became afebrile within the first 48 hours after antibiotic treatment was initiated. Cholecystectomy was considered but not pursued because of the patient’s high operative risk owing to cirrhosis. He completed a course of antibiotics and was doing well at a follow-up visit 11 months after his discharge from the hospital. Ongoing surveillance has not identified a recurrence of colon cancer.