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Fact File
Irritable bowel syndrome (IBS)
Symptoms of irritable bowel syndrome, or IBS, include constipation, diarrhoea (sometimes alternating), and abdominal pain.
Published 25/09/2006
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Background
Who amongst us will stand by our bowels when they misbehave?
They can ferment, rumble and explode, not only causing us irritation, but embarrassing us too.
Most of us can live with the occasional abdominal indiscretion. But about one in seven Australians suffer from more than just a bad bowel day. Their symptoms are severe enough to be given a name – Irritable Bowel Syndrome, or IBS.
Symptoms
People with IBS suffer constipation, diarrhoea (sometimes one alternating with the other), abdominal aches and pains (often relieved by passing a bowel motion), abdominal bloating, and flatulence. The symptoms can last days or weeks, and can seriously interrupt people's work and social lives.
The causes of aren't fully understood, but the condition is thought to be due to abnormal functioning of the walls of the large intestine.
The large intestine (also known as the colon) is a long muscular tube. The muscles in the walls alternately contract and relax, propelling the contents of the bowel forward. Water is absorbed from food waste by the bowel lining, until, by the time they reach the rectum, the contents are firm and ready to be expelled through the anus as faeces. (Nutrients are extracted higher up, in the small intestine.)
In IBS, the movement of these muscles is thought to be uncoordinated. Instead of contracting and relaxing in waves, they contract irregularly and tend to spasm.Why do the bowel muscles act in this way? Nobody knows for sure. In the past it was thought to be due to our low-fibre diet, but the condition is just as common in eastern countries where diets are higher in fibre. Particular foods can trigger symptoms, but individuals vary in which foods they are sensitive to.
There seems to be a neurological component to IBS, and the condition seems to be aggravated by stress, though whether it plays a causative role is controversial.
The bowel is heavily supplied with nerve endings, and it's thought that IBS may be due to a hypersensitivity in those nerve endings – in other words, people with IBS experience more pain from the same level of stimulation than other people. The hypersensitivity may set up a vicious cycle between the bowel and the brain, resulting in bowel symptoms.
Inflammation resulting from infection may also have a role in up to 25 per cent of cases of IBS.
IBS affects women roughly twice as much as men. Though it can occur at any age, it most commonly begins in the twenties or thirties – though again, no-one knows why.
Diagnosis
The good news about IBS is that while the symptoms are painful and disruptive, they're not a sign of – nor do they lead to – serious underlying illness.
So it's important to see your doctor to make sure it is IBS and not something else. The Gastroenterological Society of Australia advises seeing your doctor if:
- you have blood in your bowel motions
- you are over the age of 40 and your symptoms have come on recently
- you've lost weight
- you have a family history of bowel cancer.
Your GP will usually have no trouble diagnosing IBS after taking a history and a physical examination, which will usually include a digital rectal examination.
Sometimes the GP will want to do further tests if there's some doubt about the diagnosis. These tests might include a blood test, the taking of a sample of faeces to test for blood, and a colonoscopy or barium enema.
A colonoscopy is a test performed by a gastroenterologist in which a thin fibre-optic tube is inserted through the rectum and into the colon so that the lining of bowel can be visualised. It's performed under light sedation as a day-only procedure in a hospital or private clinic.
If during the procedure there is no evidence of any underlying disease like inflammation of the bowel lining or a tumour, the diagnosis of IBS is confirmed.
Treatment
Adding fibre to the diet can improve symptoms of constipation, though not usually other symptoms of IBS. A high-fibre diet means a regular breakfast of bran, muesli, or other high-fibre cereal; plus three or four pieces of fruit during the day; and a generous intake of vegetables with main meals, all washed down with plenty of water. Fibre supplements such as psyllium can also be used. (Though start off with a small amount daily, or you'll get abdominal bloating.)
At least one well-designed scientific trial has suggested that Chinese herbal medicine can relieve the symptoms of IBS. Conducted by Australian researchers, the study showed that people receiving a mixture of Chinese herbs (either individualised or standardised) had significant improvement in bowel symptoms compared to those receiving a mixture of 'fake' herbs.
Studies have also shown that hypnotherapy can be effective in relieving the symptoms of IBS (and is free of risk and side effects).
If the symptoms of IBS are distressing, they can also be relieved with pharmaceutical drugs. Constipation can be treated with laxatives, diarrhoea with anti-diarrhoeals like loperamide (trade names Imodium, Gastro-Stop), and abdominal pain with anti-spasmodic medications. Some are available over-the-counter at chemists, others require a doctor's prescription. These remedies relieve the symptoms but they don't correct the underlying condition. It's not a good idea to take them regularly.
Reviewed by Professor Nicholas Talley, University of Sydney and Nepean Hospital
Updated 19/01/2007