Irritable Bowel Syndrome

Introduction

Irritable bowel syndrome (IBS) is a symptom-based gastrointestinal disorder characterized by chronic and/or recurrent abdominal pain or discomfort, bloating and altered bowel habits in the absence of other causes for these symptoms (i.e. absence of abnormality).

  • IBS tends to be episodic, where the patient might have a history of being well for a number of weeks or months in between bouts of symptoms.
  • The cause is unknown, although it is sometimes related to particular foods, and is often precipitated or aggravated by stress.
  • A theory that it occurs due to miscommunication between the brain and the gut, and that gut coordination is affected (dysmotility).

Accroding to predominant bowel habit, IBS has been subtyped as

  • IBS with constipation
  • IBS with diarrhoea
  • IBS with mixed symptoms of constipation and diarrhoea (mixed type)
  • Unclassified



Indicative for Referral

Blood in the stool

  • Is unusual in IBS and can suggest inflammatory bowel disease (e.g. Crohn's disease and ulcerative colitis).

Patients over age 45 with recent change to bowel habit

  • IBS usually develops in young adult life (between 20-30 years old) and affects twice as many women as man.

Fever

  • Not usually associated with IBS.



Management

In addition to stress management with exercise and relaxation techniques, dietary modification has shown to be effective for some patients.

  • Eating regular meals and take time to eat.
  • Adequate noncaffeinated fluid intake.
  • Limited insoluble fiber (e.g. wheat bran) intake.
  • Suspected food products must be excluded from the diet for a minimum of 2 weeks and then gradually reintroduced to determine the food item trigger symptoms.
    • Aggravating factors may include caffeine, sweeteners sorbitol and fructose, milk and dairy products, chocolate, onions, garlic, chives and leeks.
  • Low FODMAP diet generally supported for improvement of global symptoms.

Drug treatment for IBS is usually directed at the most predominant symptom. For example,

  • Patients with mainly constipation may be treated with laxatives (e.g. soluble fibre like ispaghula husk and stimulant laxatives like bisacodyl).
  • Patients with cramping pain may be treated with antispasmodics (e.g. mebeverine, alverine, hyoscine butylbromide and peppermint oil). It is worth trying a different antispasmodic if the first has not worked.
  • Patients with diarrhoea-predominant IBS may be treated with loperamide for occasional, short-term basis.



Supplements

There is some limited evidence that probiotics (such as Lactobacillus and Bifidobacterium) can help in IBS.

  • If people wish to try probiotics, they should take them for at least 4 weeks and if they are ineffective, try another brand or stop them.



Summary

Irritable bowel syndrome (IBS) is essentially a diagnosis of exclusion, requiring a careful and thorough patient history.

  • Therefore, referral for further medical investigation is sometimes necessary, even if symptoms are suggestive of IBS.



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