Radiographics. 2015 Nov-Dec;35(7):1940-1. doi: 10.1148/rg.2015150125.
Childers BC1, Cater SW1, Horton KM1, Fishman EK1, Johnson PT1.
Colitis and enteritis are common causes of abdominal pain. Their differential diagnosis is broad, including infectious causes such as pseudomembranous colitis or Salmonella species, inflammatory causes (Crohn disease or ulcerative colitis), and ischemia. Each cause has a substantially different management strategy, which makes appropriate radiologic identification crucial. Although definitive diagnosis often relies on endoscopic biopsy results, stool culture results, or other clinical features, it is the job of the radiologist to help guide the diagnosis. The full online presentation reviews the multidetector computed tomographic (CT) appearance of infectious, inflammatory, and ischemic forms of acute enteritis and colitis and is aimed at the radiologist in training. For each cause, both general and specific multidetector CT findings in the small bowel and colon are discussed. Added focus is placed on distribution patterns and extraintestinal findings that can act as important diagnostic clues.
Infectious enterocolitis is due to bowel inflammation caused by bacteria, viruses, or parasites. A key radiologic feature of infectious enterocolitis is the distribution of inflammation produced by the offending organism. For small bowel infections, parasitic enteritis caused by Giardia and Strongyloides species most often involves the proximal small bowel, whereas bacteria such as Salmonella, Shigella, and Yersinia species affect the distal small bowel. Tuberculosis, typhlitis, and amebiasis most frequently involve the distal ileum and cecum. In the colon, Yersinia and Salmonella species frequently infect the ascending portion, whereas Shigella species infects the descending colon. Pancolitis can be seen with Clostridium difficile, cytomegalovirus, and Escherichia coli. A relatively specific CT finding is the accordion sign associated with C difficile (Fig 1).