Crohn disease vs ulcerative colitis

Dr Henry Knipe and Assoc Prof Frank Gaillard et al.

Due to the overlap in the clinical presentation of Crohn disease (CD) and ulcerative colitis (UC), imaging often has a role to play in distinguishing the two. Distinguishing features include:

  • bowel involved
    • CD: small bowel 70-80%, only 15-20% have only colonic involvement
    • UC: rectal involvement 95%, with terminal ileum only involved in pancolitis (backwash ileitis)
  • distribution
    • CD: skip lesions typical
    • UC: continuous disease from rectum up
  •  gender
    • CD: no gender preference
    • UC: male predilection
  • colonic wall
    • fat halo sign is seen in 61% of chronic UC cases, but only in 8% of CD 2
    • the bowel wall is thicker in CD than in UC (when colon involved) 2
    • serosal surface smooth in UC (95%), irregular in CD (80%) 2
  • perianal involvement
    • UC: although rectal involvement is very common, perianal complications are not as frequently seen
    • CD: common, seen in 82% of patients 2
      • stranding of ischiorectal fossa/perirectal fat (73%)
      • fistulas/sinus tracts (22%)
  • mesenteric creeping fat
    • CD: common in chronic cases
    • UC: not seen, as small bowel not involved
  • abscess formation
    • CD: common, eventually seen in 15-20% of patients
    • UC: uncommon
  • extraintestinal complications

Article information

rID: 6831
Section: Approach
Synonyms or Alternate Spellings:
  • Ulcerative colitis versus Crohn's disease
  • Crohn's disease versus ulcerative colitis
  • Crohn disease versus ulcerative colitis
  • CD vs UC
  • CD versus UC
  • Ulcerative colitis versus Crohn disease
  • UC vs CD

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Cases and figures

  • Case 1: UC with lead pipe appearance
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  • Case 2: CD with comb sign
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