The basics - Irritable bowel syndrome

Lifestyle modification is often the best method of managing the relapsing condition of irritable bowel syndrome.

IBS may cause symptoms of bowel spasm and abdominal pain
IBS may cause symptoms of bowel spasm and abdominal pain

IBS is a chronic, relapsing and often lifelong disorder. The term refers to a heterogenous group of abdominal symptoms for which no organic abnormality can be found. It should be regarded as a diagnosis of exclusion with care taken to consider and rule out any pathology before the label is applied.

Clinical features
The condition is characterised by generalised abdominal discomfort that is often accompanied by a change in bowel habit and shows relief from defecation.

Symptoms that may be encountered alongside abdominal discomfort include diarrhoea, constipation or both, increased flatus, food intolerance, bloating or distension. Disordered intestinal motility is thought to result in the symptoms.

Although in some cases this appears to be triggered by an organic cause, there is frequently no obvious trigger. There is undoubtedly a psychological component.

Diagnosis
The NICE guidelines for IBS were issued in February 2008 and provide diagnostic criteria for the condition.1

The most common presenting feature of IBS is generalised, crampy abdominal pain associated with bowel activity.

For many the pain is relieved by defecation and may be accompanied by a change in bowel frequency. Often bloating or distension is present. Women are commonly affected; stress is a recognised precipitant.

Lethargy, nausea, backache and even bladder symptoms may also occur. The non-specificity of such symptoms can make IBS a challenging diagnosis to make and various investigations are considered. The NICE guidelines offer quite specific criteria for IBS diagnosis, including a six-month time frame for symptoms to persist, in the absence of the red flag features listed below, prior to investigation.

Investigations
In people who meet the diagnostic criteria, NICE recommends taking an FBC, plasma viscosity/ESR, CRP and a coeliac screen. A food diary can also provide useful information and should be encouraged. TFTs and stool tests are not recommended routinely and unnecessary endoscopy or radiological investigation should be avoided.

Red flags
The symptoms of IBS have considerable overlap with a symptom profile that may suggest more serious bowel pathology and it is the responsibility of a clinician to rule this out.

Various red flags should raise suspicion; in particular, patients older than 60 years presenting with a change in bowel habit, any patient with rectal bleeding, unintentional weight loss or anorexia.

A patient with a positive family history of bowel or ovarian cancer should be referred for secondary care investigation.

Blood test results showing anaemia, raised inflammatory markers or positive screens for coeliac disease will also require further investigation. In women, consideration should be given to the presence of ovarian pathology and, in some cases, pelvic examination and investigation may be appropriate.

DIFFERENTIAL DIAGNOSES
  • Bowel cancer
  • Inflammatory bowel disease
  • Ischaemic colitis
  • Diverticulitis
  • Coeliac disease
  • Gynaecological pathology - ovarian cancer or endometriosis
  • Infective gastroenteritis - giardiasis
  • Anxiety and depression

Lifestyle modification
Treatment is rarely immediately or totally successful and it is useful to manage patient expectation from the outset. Various strategies may be required and management for one case is rarely the same as that required in another.

Lifestyle modification is vital. Patients should be encouraged to capitalise on their leisure time, to take regular aerobic activity and create relaxation time.

General advice on diet and nutrition is important and self-help leaflets can be useful. Fibre intake should be adjusted in accordance with symptom profile. High intake of insoluble fibre should be avoided and replaced by soluble fibres such as ispaghula powder or oat-based foods. Probiotics may be useful and tried over a four to eight week period.

Although there has been some anecdotal success using aloe vera, this has not been clinically proven in trials and its use is discouraged by NICE.2 In some cases, food diary information may suggest that diet plays a key role in a patient's IBS and referral to a dietician may help.

Pharmacological treatment
Medication use will generally depend on predominant symptoms. Antispasmodic agents can be useful alongside dietary and lifestyle modifications.

If constipation prevails, soluble fibres can be useful, although lactulose should be avoided. If the main concern is diarrhoea, loperamide is the antimotility agent of choice. Such medications should be used with dose titration.

Second-line medications to consider include tricyclics for analgesic effect or SSRIs if tricyclics are not useful. Potential side-effects must be considered and patients should have regular followup in the early stages.

  • Dr Cumisky is a locum GP in Bath.
RED FLAGS
  •  >60 years with more than six weeks altered bowel habit
  • Rectal bleeding
  • Anorexia
  • Unintentional weight loss
  • Family history of bowel or ovarian cancer
  • Abdominal masses
  • Rectal masses
  • Raised inflammatory markers
  • Anaemia
  • Raised TTG

REFERENCES

1. NICE. Irritable bowel syndrome in adults CG061. London, NICE, 2008. www.nice.org.ukcg061

2. Davies K, Philpott S, Kumar d, Mendall M. Randomised double-blind placebo-controlled trial of aloe vera for irritable bowel syndrome. Int Clin Pract 2006; 60: 1080-6

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