• Common in older patients
  • Muscle abnormality in sigmoid colon with out pouching from colonic wall
  • Deposition of elastin in taeniae cause contraction and shortening of bowel with corrugation of mucosa and circular muscle layers – this causes thickening of sigmoid with interdigitating folds
  • Diverticula arise at points of weakness where the vasa recta penetrate the circular muscle layer
  • Each diverticulum is a pouch of mucous membrane with vey thin covering of longitudinal muscle
  • Commonest in sigmoid colon, localized to proximal colon in 10% cases
  • Diverticulitis
    • Most common complication
    • Due to fecal retention within diverticulum
    • Leads to ischemic necrosis with microperforation
    • Formation of pericolic abscess
    • Adherence of chronic inflammatory mass may result in fistula formation (adjacent to urinary bladder)
    • Rarely abscess can perforate directly into peritoneal cavity (fecal peritonitis)
  • Bleeding can occur from a diverticulum
    • More common from wide-mouthed right side colon diverticula
  • USG: in diverticulitis, graded compression at colic site shows the pericolic abscess
  • CT
    • High attenuation
    • Mimics polyp on 3D endoluminal view
    • Diverticulitis
      • Diverticular changes
      • Colonic wall thickening
      • Inflammatory reaction in pericolic fat with ‘fat stranding’ and edema
      • Fluid tracks along root of mesentery
      • Abscess in 35% cases. <3 cm treated with antibiotics. 4 cm or more benefits from catheter drainage
  • Distinguishing diverticulitis from malignancy is difficult
    • Long segment lesions favor inflammation rather than malignancy
  • Fistula often involves urinary bladder
    • Conventional contrast enema may be used
    • CT/MRI sufficient
    • Air in urinary bladder, abscess in urinary bladder wall, bladder wall thickening or adherent adjacent colon may be seen
  • Giant cyst formation
    • Rare complication
    • Pseudocyst with no epithelial lining due to expansion of a walled-off subserosal perforation (Differential: duplication cyst)
Read more

Sai, Victor F., et al. “Colonoscopy after CT diagnosis of diverticulitis to exclude colon cancer: a systematic literature review.” radiology 263.2 (2012): 383-390.

Tack, Denis, et al. “Suspected acute colon diverticulitis: imaging with low-dose unenhanced multi–detector row CT.” Radiology 237.1 (2005): 189-196.

Goh, Vicky, et al. “Differentiation between diverticulitis and colorectal cancer: quantitative CT perfusion measurements versus morphologic criteria—initial experience.” Radiology 242.2 (2007): 456-462.

Lips, Leonie MJ, et al. “Sigmoid cancer versus chronic diverticular disease: differentiating features at CT colonography.” Radiology 275.1 (2015): 127-135.