Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a ‘functional’ gastrointestinal disorder. This means that the cause of it is not a specific and identifiable disease entity, but a plausible consequence of disordered functioning of the bowels. Other names for IBS that occur in literature include “spastic colon”, “irritable colon” and “nervous colon”.

IBS is characterized by abdominal pain or discomfort which is often relieved by defecation and is related to a change in bowel frequency and stool form. There may also be difficulty in passing stools, needing straining, passage of mucus and also a subjective sensation of bloatedness and abdominal distention. There are various sub-types of IBS, depending on whether the symptoms are related more to constipation, to diarrhoea or to alternating constipation and diarrhoea.

The cause of IBS is uncertain. Theories include altered gastrointestinal motility which results in abnormally quick or slow movement of the bowels; abnormal sensitivity to the sensation of movement of the contents of the intestines; an association with depression, stress or anxiety in the patient, or microscopic inflammation of the bowels perhaps caused by bacteria which have not been identified.

IBS is a substantial problem in most countries, with a prevalence of about 4% in Singapore and up to 20% in UK and USA. Some of the variation may be due to cultural differences in health seeking behaviour. Americans and Europeans suffer more from IBS than Asians and Africans. It is also more common amongst Caucasian women and Indian men. Half of these patients have symptoms before the age of 35, and IBS may even occur in childhood. In patients above 40 years, more serious conditions must be excluded before IBS is diagnosed. IBS is an important condition in the community because up to 20% of all IBS sufferers seek medical care, and up to 50% of all gastroenterological referrals are for investigation of suspected IBS. Work absenteeism, lost wages and economic losses due to IBS are significant.

When a patient appears with symptoms suggestive of IBS, a careful history must be taken with particul