A 55-year-old woman with sudden onset abdominal pain, bloody diarrhea, and a history of atrial fibrillation. CT abdomen shows segmental thickening of the splenic flexure with pericolonic fat stranding and a 'double halo sign' (target sign) on contrast-enhanced CT. This finding is most characteristic of:

• A Ulcerative colitis
• B Crohn disease
• C Ischemic colitis ✓
• D Infectious colitis

Explanation

Ischemic colitis classically affects watershed areas (splenic flexure) in patients with cardiovascular risk factors or arrhythmias. CT shows segmental bowel wall thickening with the double halo or target sign, pericolonic fat stranding, and often the 'thumbprinting' sign. The splenic flexure is the most common site (Griffith point). Ulcerative colitis is continuous from the rectum. Crohn disease shows skip lesions and fistulas. Infectious colitis is usually diffuse.

Reference: Radiology Review Manual, W Dahnert, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.