A patient presents with fever and sudden left lower quadrant pain. The best initial diagnostic study is which?

• A. Barium enema
• B. CT abdomen
• C. Flex sigmoidoscopy
• D. Colonoscopy

Answer: (D)

Fever with sudden left lower quadrant pain points to an acute inflammatory process such as diverticulitis. The best initial test is a CT scan of the abdomen and pelvis with IV contrast. It quickly confirms the diagnosis by showing colonic wall thickening and pericolic fat stranding, and it detects complications like abscess, perforation, or obstruction, which guide management.

Barium enema is avoided in the acute setting because insufflation and contrast can worsen inflammation and risk perforation, and it’s less reliable for acute diverticulitis. Endoscopic approaches (flexible sigmoidoscopy or colonoscopy) are relatively contraindicated during an acute inflammatory attack due to the risk of perforation; they’re reserved for after the inflammation has resolved or for other indications, not for initial evaluation. Therefore, CT abdomen with contrast is the most appropriate initial diagnostic study.