Dr Mark Cottrill evaluates PCSG guidance on diagnosing and treating patients with irritable bowel syndrome


The management of irritable bowel syndrome (IBS) in general practice is far from ideal. The disease mechanism is poorly understood, and doctors are often uncomfortable in making a positive diagnosis. Medical treatment is frequently ineffective. The patient's agenda may be different from the physician's agenda. This has the potential to cause conflict, frustration and disappointment. It is therefore timely that the Primary Care Society for Gastroenterology has recently published Irritable Bowel Syndrome: Guidelines for General Practice.1 (see Guidelines in Practice Vol 4(9)).

The team is to be congratulated on its comprehensive review. Sadly, evidence-based medicine is lacking for IBS. Because the disease has an array of symptoms, no obvious end points and a high placebo response, many studies are of poor quality. When good evidence from studies is lacking, consensus becomes valuable. Although the guideline authors recognise this, the finished product reads more like a literature review rather than offering clear practical advice.

GPs are proficient in distinguishing IBS from organic disease. The Rome II criteria2 quoted in the guidelines are not well known in primary care but provide a safe diagnosis. Prior to this, Manning and his group3 devised criteria that are still valid in making a positive diagnosis. Although by no means perfect, symptom-based criteria are critical to the diagnosis of IBS. The guidelines are strong on this point and should help the doctor feel comfortable with a positive diagnosis.

However, in the next section, Making a safe diagnosis, the guidelines seem to be conflicting. A series of differential diagnoses, including giardiasis, Crohn's disease, coeliac disease, pancreatic disease, lactose intolerance and bile salt malabsorption, would have most GPs reaching for their referral pad. The section on management offers little practical help; a structured management plan, and a flow diagram would have been invaluable.

The current consensus of the management of IBS, supported by the British Society of Gastroenterology guidelines (see Guidelines in Practice Vol 4(3)) is to make a positive diagnosis with the minimum of investigation. A careful history, including a description of the pain and bowel habit is critical. Physical examination is mandatory and diagnostic tests should be ordered according to the patient's age, predominant symptoms and severity of symptoms. For young patients with typical symptoms, a full blood count, ESR and perhaps endomysial antibodies (for coeliac disease) should suffice.

Emphasis should be placed on the initial evaluation, because establishing an effective clinical relationship is probably the most cost-effective strategy. Education, reassurance, empathy and setting reasonable objectives are vital in the initial consultation. Dietary and lifestyle changes, education and reassurance are often sufficient to control symptoms. Follow-up is essential but not emphasised in the guidelines. At review, if symptoms progress or change, there are options for further investigation tailored to the patient.

The guidelines state that drug treatment should be targeted at the most troublesome symptoms. Expert opinion recommends that IBS patients be divided into subgroups depending on symptoms as a basis for therapy. Patients may be categorised as constipation predominant (C-IBS), diarrhoea predominant (D-IBS), alternating constipation and diarrhoea (A-IBS) and pain predominant. This was not emphasised by the PCSG group but can be valuable in targeting treatment.

The PCSG has made a brave attempt at providing help for GPs in managing IBS. However, I hope that the revision (due next year) will strive to offer more practical advice.


  1. www.pcsg.org.uk
  2. Thompson WG, Longstreth GF, Drossman DA et al. Functional bowel disorders and functional abdominal pain. Gut 1999; 45(Suppl2:II): 43-7.
  3. Manning AP, Thompson EG, Heaton KW et al. Towards a positive diagnosis of the irritable bowel. Br Med J 1978; 2: 653-4.