Irritable Bowel Syndrome

Basics

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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