IBS

• Irritable bowel syndrome is a functional disorder where there is no identifiable underlying bowel disease
• · Disturbance of the gut-brain interaction resulting in troublesome abdominal and intestinal symptoms

  · Occurs in up to 20% of the population- more common in women and younger adults
• · I = Intestinal discomfort (abdominal pain relating to the bowel)

  · B = Bowel habit abnormalities

  · S = Stool abnormalities (watery, loose, hard or with mucus)
• Specific symptoms vary with individuals. Common symptoms:

  · Abdominal pain

  · Diarrhoea

  · Constipation

  · Fluctuating bowel habit

  · Worse after eating

  · Improved by opening bowels

  · Passing mucus
• Symptoms can be triggered or worsened by:

  · Anxiety/depression/stress

  · Sleep disturbance

  · Illness

  · Medications

  · Certain food

  · Caffeine

  · Alcohol
• A thorough history and examination are required to identify the typical features of IBS and exclude red flags for other underlying pathology:

  FBC for anaemia (bowel cancer and IBD)

  Inflammatory markers (ESR and CRP)

  Coeliac serology- anti-TTG antibodies

  Faecal calprotectin for IBD

  • CA125 for ovarian cancer (causes non-specific symptoms like bloating)
• NICE guidelines state that for an IBS diagnosis, differentials need to be excluded and patient should have at least 6 months of abdominal pain/discomfort with one of the following:

  • Pain relieved by opening bowels
  • Bowel habit abnormalities
  • Stool abnormalities
• Lifestyle advice for IBS:

  Enough fluids

  Regular small meals

  Adjusting fibre intake according to symptoms

  Limit caffeine, alcohol and fatty foods

  Low FODMAP diet

  Probiotic supplements

  Reduce stress

  • Regular exercise
• First line treatment depends on IBS symptoms:

  • Loperamide for diarrhoea
  • Bulk forming laxatives (avoid lactulose as can cause bloating)
  • Antispasmodics for cramps
  • Linaclotide is a special secretory drug for constipation in IBS when first line laxatives are inadequate
  • If symptoms remain uncontrolled: low dose tricyclic antidepressants (amitriptyline), SSRI antidepressants, CBT or specialist referral
• Loperamide:

  · Binds to the opiate receptor in the gut wall- inhibits the release of acetylcholine and prostaglandins

  · Reduces propulsive peristalsis and increasing intestinal transit time

  · Increases tone of the anal sphincter, thereby reducing incontinence and urgency
• Loperamide is contraindicated in infective diarrhoea and ulcerative colitis - toxic megacolon
• Antispasmodics:

  · Bind to the muscarinic receptors on the GI smooth muscles

  · Inhibition of calcium influx into smooth muscles

  · Block acetylcholine from binding to these receptors- decrease smooth muscle contraction and relieves the spasm
• Tricyclic antidepressants in IBS:

  · Amitriptyline reduces brain activation during rectal distension in IBS patients during mental stress

  · Probably due to a CNS effect rather than actually acting on the bowel

  · Reduction in stress related exacerbations of symptoms
• Osmotic laxatives are poorly absorbable and draws water into the lumen of the bowel

  E.g. lactulose and sorbitol
• Bulk forming laxatives retain fluid in the stool and increase stool weight/consistency

  important to drink lots of fluids for these laxatives to work - without can lead to bloating and bowel obstruction
• Stimulant laxatives stimulate the myenteric plexus and Auerbach plexus

  = increased intestinal secretions and motility

  Also decrease water reabsorption from the lumen of the bowel

  E.g. senna