Findings: Sigmoid diverticulosis, thickened segment, surrounding stranding/fluid. No complications. Findings in keeping with acute uncomplicated diverticulitis.

Objectives:

• To review the CT appearance of uncomplicated diverticulitis

• To review the complications of diverticulitis that should be assessed for

• To review differential considerations - primarily colon cancer and colitis

Protocolling:

• Contrast enhanced CT +/- rectal contrast

Key points:

• Colonic diverticulosis are actually pseudo-diverticular (outpouching of just mucosa/submucosa)

• Etiology:

  • Impaction at mouth of diverticula, inflammation, and microperforation

• Diverticulosis alone often causes muscular hypertrophy/thick appearing colonic wall (with no acute diverticulitis)

• CT Findings in Uncomplicated Diverticulitis:

  • Thickened loop of large bowel containing multiple diverticula

  • Adjacent inflammatory change (stranding, fluid)

  • Mesenteric congestion/egorgement

  • Small bubbles of pericolonic gas = “microperforation”

• Complications:

  • Macroperforation - more extensive extra-luminal gas, abscess

  • Free perforation (more distant free gas)

  • Fistulization - follow the gas/contrast (i.e. bladder, vagina, to skin)

  • Mesenteric vein/portal vein thrombosis

  • Hepatic abscess

• Differential considerations:

  • Colon cancer - overlapping features

    • Should suggest colonoscopy after resolution of acute episode.

    • Signs suggestive of cancer: shorter segment (<10cm), adjacent lymphadenopathy, less pericolonic inflammatory change.

  • Other colitis:

    • More uniform wall thickening, less pericolonic inflammatory change