Involvement of the small bowel by Crohn's disease can be classified using the changes seen on imaging studies. The pattern seen at a specific point is affected by disease activity and therapeutic interventions.


A single bowel segment may show more than one pattern, and adjacent bowel segments may show different patterns.


Other Changes Seen


superficial aphthae

minimal edema (minimal thickening or distortion of folds)

active inflammation, minimal

deep ulcerations, cobblestone mucosa

marked wall thickening from transmural inflammation; target sign; "comb sign", obstruction secondary to spasm

active inflammation, severe


mild prestenotic dilatation; no mural edema; minimal bowel wall thickening; minimal decrease in luminal diameter

fibrostenotic, minimal stenosis


prestenotic dilatation; marked bowel wall thickening with soft tissue density; marked decrease in luminal diameter

fibrostenotic, severe stenosis

deep fissuring ulcers, sinus tracts

fistulae to skin or other organs, presence of an inflammatory mass



mucosal atrophy; regenerative polyps; no mural edema (minimal decrease in luminal diameter)

reparative or regenerative


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