Irritable Bowel Syndrome

Dr Bruce Davies

Sept 2001 Bruce Davies 2

Introduction First described in 1771. 50% of patients present <35 years old. 70% of sufferers are symptom free after 5

years. GPs will diagnose one new case per week. GPs will see 4-5 patients a week with IBS. Point prevalence of 40-50 patients per 2000

patients.

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What Is IBS? A syndrome. One man’s

constipation is another man’s normality.

Cause unknown. 20% seem to start

after an episode of gastroenteritis.

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Diagnostic Criteria Rome 11 Diagnostic criteria.

Manning’s Criteria.

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Rome 11 Diagnostic Criteria. At least 12 weeks history, which need not

be consecutive in the last 12 months of abdominal discomfort or pain that has 2 or more of the following:– Relieved by defecation.– Onset associated with change in stool

frequency.– Onset associated with change in form of the

stool.

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Rome 11 Diagnostic Criteria. Supportive symptoms.

– Constipation predominant: one or more of: BO less than 3 times a week. Hard or lumpy stools. Straining during a bowel movement.

– Diarrhoea predominant: one or more of: More than 3 bowel movements per day. Loose [mushy] or watery stools. Urgency.

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Rome 11 Diagnostic Criteria.

– General: Feeling of incomplete evacuation. Passing mucus per rectum. Abdominal fullness, bloating or swelling.

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Manning’s Criteria. Three or more features should have been

present for at least 6 months:– Pain relieved by defecation.– Pain onset associated with more frequent stools.– Looser stools with pain onset.– Abdominal distension.– Mucus in the stool.– A feeling of incomplete evacuation after

defecation.

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Associated Symptoms In people with IBS in hospital OPD.

– 25% have depression.– 25% have anxiety.

Patients with IBS symptoms who do not consult doctors [population surveys] have identical psychological health to general population.

In one study 70% of women IBS sufferers have dyspareunia.

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Associated Symptoms Stressful life events are associated. Compared with controls people with

IBS are less well educated and have poorer general health.

Women:Men = 3:1.

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Reasons to Refer Age > 45 years at

onset. Family history of bowel

cancer. Failure of primary care

management. Uncertainty of

diagnosis. Abnormality on

examination or investigation.

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Urgent Referral Constant abdominal

pain. Constant diarrhoea. Constant

distension. Rectal bleeding. Weight loss or

malaise.

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Subtypes Diarrhoea predominant. Constipation predominant. Pain predominant.

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Differential Diagnosis Inflammatory bowel disease. Cancer. Diverticulosis. Endometriosis.

A positive diagnosis, based on Manning’s criteria may provoke less anxiety than extensive tests.

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Examination Results should be

normal or non-specific. Abdomen and rectal

examination. FBC, CRP. No consensus as to

whether FOBs or sigmoidoscopy is needed.

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Treatment Patients’ concerns. Explanation. Treatment

approaches.

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Patients’ Concerns. Usually very concerned about a

serious cause for their symptoms. Take time to explore the patients

agenda. Remember that investigations may

heighten anxiety.

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Explanation. Must offer a plausible reason for symptoms. Even if cause is unknown, patients require

some explanation. Drawing a parallel with baby colic may help. Stress is currently a socially acceptable

explanation for many symptoms in life.

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Treatment Approaches. Placebo effect of up to 70% in all IBS

treatments. Treatment should depend on symptom

sub-type. Often considerable overlap between

sub-groups.

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Antidepressants Poor evidence for efficacy. Better evidence for tricyclics. Very little evidence for SSRIs.

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Diarrhoea Predominant. Increasing dietary fibre is sensible

advice. Fibre varies, 55% of patients will get

worse with bran. “Medical fibre” adds to placebo effect. Loperamide may help.

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Constipation Predominant. Increased fibre. Osmotic laxatives helpful. Ispaghula

husk is one. Stimulant laxatives make symptoms

worse. Lactulose may aggravate distension

and flatulence.

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Pain Predominant. Antispasmodics will help 66%. Mebeverine is probably first choice. Hyoscine 10mg qid can be added. Bloating may be helped by peppermint

oil. Nausea may require metoclopramide.

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Diet Dietary manipulation may help. Food intolerance is common food

allergy is rare. Relaxation therapies may be useful

adjunct.

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Referral About 15% of patients seen by GPs

with IBS are referred. Gastroenterology – Mainly upper GI

symptoms. General Surgical – Lower GI

symptoms.

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Self-help IBS network, St

John’s House, Hither Green Hospital, Hither Green Lane, London SE13 6RU

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Audit? Numbers on repeat prescription for anti-

spasmodics. Do they use their drugs as prescribed? What other medications do they use? Referral rates? What investigations are done? Protocol? Formulary?

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Psychological Thoughts Should a mental health assessment

always be done? Should all therapy be directed at

psychological causes? Is IBS a physical or a somatisation

disorder?