Irritable Bowel Syndrome

Definition:

• Relapsing abdominal pain with bloating, flatulence and change in bowel habits (alternating diarrhea and constipation) that improves with defecation, seen in middle aged women.
• This condition is a diagnosis of exclusion

Etiology and association

• Unknown etiology, mostly women with history of childhood abuse.
• Unknown cause of increase in frequency of normal peristalsis and segmentation contraction of bowel.
• Can be diarrhea predominant, Constipation predominant or both (alternate consti-diarrhea).

Symptoms and Clinical Presentation:

• Abdominal pain/cramping with change in bowel movements that gets better post defecation
• 20% constipation only, some diarrhea alone only, rest switch between diarrhea and constipation
• All have abdominal pain/bloat/gas/flatulence.
• No Bleeding, No Weight loss, No fever, No nocturnal Symptoms. No GI Pathology appreciated
• Get better with Fiber rich foot or go away with bowel movements

Diagnosis

• (Rome criteria) – (at least 3 months; 3 days per month) 2/3 below.
  • Change in Form and Appearance of Stool
  • Diarrhea alternating with constipation [ie change in frequency]
  • Pain relived by BM or by change in bowel habit (when you diarrhea, pain gone)
• Colonoscopy – normal mucosa
• Stool guaic negative, No WBC, Culture/Ova all negative, Abdominal CT negative

Treatment and Management

• Best initial: High fiber diet and increase the bulk of the stool (help relief pain, if not use medication)
• Medication for pain of IBD
• Pain (antispasmotics) – Hyoscyamine, Dicyclomine, Belladonna alkaloid [relax bowel]
  • Relax muscle wall contracture hence diminish pain – Can worsen GERD!
  • If refractory pain can use TCA (anti HAM) can relax bowel and treat depression since many have depression anyways (amitriptyline is anticholinergic, relive neuropathic pain, antidepressant)
• Medication for Diarrhea-Constipation predominant;
  • Diarrhea predominant
    • Rifaximine: non-absrobed Abx
    • Loperamide, Diphenoxylate,
    • Alosetron (arrest stool via 5HT)
    • EluxadolineL mu-opioid receptor agonist for diarrhea, relieves pain/slows bowel.
  • Constipation predominant
    • Always Fiber
    • Polyethylene glycol (PEG): non-absorbed bowel lubricant. If don’t work use below 2: lubipristone, Linaclotide
    • Lubiprostone (Cl channel activator that increase BM frequency)
    • Linaclotide (guanylate cyclase agonist) also like lubirpistone used if PEG not work.
    • Tegaserod (Side effects include diarrhea. This drug manipulate 5HT),