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Functional Bowel Disorders

Woman suffering from functional bowel disorder

Functional bowel disorders, comprising of constipation, diarrhoea, bloating and Irritable Bowel Syndrome (IBS) are a common reason for patient presentation to the General Practitioner and Gastroenterologist.

IBS alone is thought to affect 10% of the population at any one time, and a staggering 40% of people are affected over their lifetime. There is a female preponderance. Although non life-threatening, these disorders have a significant impact on the individual and the community through decreased productivity at work and sick days.

The diagnostic criteria used for the diagnosis of Irritable Bowel Syndrome are the Rome III Criteria; which include:

  • Recurrent abdominal pain or discomfort at least 3 days per month in the last 3 months associated with two or more of:
  • Improvement with defecation
  • Onset associated with a change in frequency of stool
  • Onset associated with a change in form (appearance) of stool

The criterion must be fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.

IBS is a diagnosis of exclusion. More recently, a targeted approach with the use of careful history taking and judicious use of selected investigations can help determine which patients require specialist referral.

A recent paper by Linedale1 in the Medical Journal of Australia provided guidelines for local medical practitioners to use in diagnosing and risk stratifying patients with IBS. These included:

Red flags to elicit in history:

  • New onset symptoms if > 50 years of age (within 6 months).
  • Unexplained weight loss (> 3 kg or 5% bodyweight).
  • Iron deficiency ± anaemia.
  • Melaena, overt rectal bleeding, positive FOBT.
  • Abdominal pain awaking patient from sleep.
  • Diarrhoea disturbing sleep or faecal incontinence.
  • Documented unexplained fever.
  • Family history of colon cancer (1 FDR < 60 years, or > 1 FDR any age).
  • Family history of IBD in symptomatic patient (1 FDR).
  • Family history of coeliac disease in symptomatic patient (1 FDR).

Investigations to be considered:

  • FBC.
  • Iron studies.
  • CRP / ESR.
  • Coeliac serology.
  • Stool PCR and C.difficile toxin.
  • Albumin.
  • Parasite screening if overseas travel.
  • Bowel cancer screening as per normal.
  • Faecal calprotectin.

If the patient has no red flags on history and normal investigation results, reassurance can be given to the diagnosis of IBS. An elevated faecal calprotectin, presence of red flags or abnormal investigation results require specialist review.


Linedale E, Andrews J. Diagnosis and management of irritable bowel syndrome: a guide for the generalist. Med J Aust 2017; 207 (7): 309-315xt.