Irritable Bowel Syndrome



  • Syndrome of abdominal pain associated with altered bowel habits and no other pathology explaining symptoms
  • Prevalence estimated to be 10–20%


  • Uncertain pathophysiology, but many possibilities
  • Altered GI motility:
    • Increased gut sensitivity (visceral hyperalgesia):
      • Exaggerated response to normal GI physiology
  • Mucosal inflammation:
    • Postinfectious:
      • Prevalence of IBS after Giardia lamblia infection above 40%
  • Mucosal lymphocyte infiltration
  • Altered microflora in small bowel or feces
  • Food sensitivity is a possibility but not proven
  • Psychosocial dysfunction:
    • More anxiety, somatoform disorders, and history of abuse in patients who seek care
    • No evidence of increased psychiatric illness in those who do not seek care

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