In an acute presentation suggestive of Crohn disease, which imaging test is most appropriate to start?

• A. KUB
• B. Abdominal CT
• C. Barium enema
• D. Sigmoidoscopy

Answer: (A)

In an acute presentation where Crohn disease is suspected, the priority is to rapidly assess for potentially life-threatening complications and stabilize the patient. A plain abdominal radiograph (KUB) is the best starting imaging because it quickly evaluates for obstruction, dilated bowel loops, and free air from perforation. These findings directly guide urgent management and the need for further testing.

A CT scan of the abdomen provides detailed information about the extent and complications of Crohn disease (such as fistulas, abscesses, and bowel wall thickening), but it’s typically used after initial stabilization or when obstruction or perforation isn’t evident on plain X-rays. It also involves more radiation and contrast exposure, making it a step after the initial plain film.

Barium enema is less favorable in this acute context because it can worsen obstruction and is less informative for small bowel Crohn’s disease, which is often the focus in Crohn’s. Sigmoidoscopy examines mucosa of the distal colon but does not assess the small bowel well and is not a first-line imaging in an acute suspected Crohn’s presentation.