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colitis_ischaemic

ischaemic colitis

introduction

epidemiology

  • 90% occur in >60 yr olds
  • younger pts tend to have either:
    • vascular disease
    • arteriosclerotic heart disease
    • diabetes
    • hypercoagulopathy
    • vasoconstrictive drugs - cocaine, digoxin
  • chronic ischaemia may be due to Sx, esp. AAA repair (0.1-10% of AAA repairs)
  • most cases due to arteriole shunting, spasm or poor perfusion of mucosal vessels
  • some cases are caused by embolus or thrombus of mesenteric artery
  • most cases involve the splenic flexure with sparing of rectum as this is less dependent on inf. mesenteric A

pathology

there are three types:

  • transient, reversible ⇒ mucosal sloughing and then regeneration (most common type)
  • stricturing - haemorrhagic infarction of mucosa ⇒ ulceration, healing by fibrosis
  • gangrenous - complete bowel wall infarction ⇒ perforation, peritonitis and death

clinical presentation

  • characteristically, acute onset

AXR and CT findings of ischaemic colitis

  • most plain films are normal or show a non-specific ileus pattern!
  • thickening of the colonic wall, with luminal narrowing and transverse ridging
    • NB. pseudothickening of the wall is NOT a sign of ischaemia and may be due to:
      • ascites as the loops are floating in fluid and become separated from other loops
      • peritonitis
      • loops containing more fluid than air causing an optical illusion
  • “thumbprinting” of the bowel wall due to oedema
  • fixed, rigid, tubular, ahaustral bowel loops
  • pneumatosis (gas in bowel wall):
    • benign causes of pneumatosis include collagen vascular diseases, steroids, COPD and idiopathic causes.
    • this can be seen in any severe bowel insult resulting in bowel wall necrosis and is a classic feature of necrotizing enterocolitis of the newborn infant.
  • free gas in peritoneal cavity (uncommon) or in mesenteric veins and portal vein (these findings are ominous and indicate infarction)
colitis_ischaemic.txt · Last modified: 2018/08/11 01:29 (external edit)