Refers to a group of symptoms, including abdominal pain and discomfort, bloating, and change in bowel habit, for which no underlying cause or pathology can be identified
Aetiology
Onset generally <45 but persists into old age
Risk factors
Female gender (2:1)
Family history
Mental health problem e.g. anxiety
Clinical presentation
Symptoms
Abdominal pain often relieved by defaecation
Misbehaving bowels - constipation (IBS-C), diarrhoea (IBS-D) or mixed (IBS-M)
Signs
May be tenderness in left iliac fossa
Investigations
Diagnosis is symptom based
Rome III diagnostic criteria
Recurrent abdominal pain or discomfort at least 3 days per month in the last 3 months associated with 2 or more of the following:
Improvement with defaecation
Onset associated with change in frequency of stool
Onset associated with a change in the form of stool
Bloods
Used to rule out other causes, should be normal
FBC, coeliac serology, CRP, TSH
AXR
Consider selectively
Management
Dietary advice (first line)
‘If it upsets you, don’t eat it’
Increase fibre in IBS-C, decrease fibre in IBS-D
Low FODMAP diet (second line)
Group of short-chain carbohydrates poorly digested in small intestines leading to fermentation and osmotic changes in large bowel
Eliminate all FODMAP for 2-6 weeks, then reintroduce gradually to identify triggers
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