Irritable Bowel Syndrome
Irritable bowel syndrome, commonly called IBS, is a condition that causes abdominal pain and a change in the way the bowel works. Some affected people get diarrhoea (loose and frequent stools), some develop constipation (hard stools which are difficult to pass) while others alternate between the two.
Other symptoms include bloating and the feeling of not having emptied the bowels completely, so needing to return to the toilet shortly after a bowel action. Many people with IBS find that their symptoms are made worse by stress and by certain foods.
IBS does not usually cause weight loss or rectal bleeding and people with IBS do not usually need to get up in the night to open their bowels.
IBS is a disorder of the way the muscles and nerves in the gut work. It is called a ‘functional gut disorder’ because it is a problem with gut function rather than a problem with the structure of the bowel, such as colitis, Crohn’s disease or cancer. In IBS the gut looks normal, both to the naked eye and under the microscope, but it doesn’t work properly. Strictly speaking, IBS is just one of a number of functional gut disorders. However, IBS is often used as an overall term for these conditions as it is a term people are familiar with.
What causes IBS?
A specific cause for IBS has not been identified. However, we know that there are several things that can trigger IBS symptoms. For example, a proportion of people with IBS have a clear history of having had an episode of infectious gastroenteritis prior to developing IBS; this is called ‘post-infectious’ IBS.
Similarly we know that there are several things that can make IBS worse. It is very common for people to develop gut symptoms when they are under stress. This is probably even more common in people with IBS – it is not that the stress is the cause of their IBS, but stress certainly makes the symptoms worse.
Food can also be an important trigger of symptoms for people with IBS. Almost any food item can cause symptoms and, although there are some which do so more commonly than others, there are no hard and fast rules about which foods people with IBS should avoid. Unfortunately, the majority of tests that are available to identify which foods are problematic for an individual are at best ‘unproven’. Breath testing to identify incomplete lactose and / or fructose absorption may be an exception. In our experience, an in depth consultation with a Specialist Dietician with an interest in IBS can be invaluable.
How is IBS diagnosed?
IBS is diagnosed by matching up symptoms with examination findings and diagnostic test results. Standard tests are always normal in IBS. Blood tests, stool tests and a variety of endoscopic and/or radiological tests are used to exclude other serious conditions. The necessary tests vary from person to person depending on what symptoms are described. Endoscopy tests may include gastroscopy (to examine the stomach and first part of the small bowel), colonoscopy (to examine the large bowel and last section of the small bowel) and capsule endoscopy (to examine the rest of the small bowel). X-ray tests may include ultrasound, CT and MRI scans. Breath testing for sugar malabsorption may also be useful.
Most people need only some of these tests and you will be able to discuss the alternatives and which is the most appropriate for you.
How is IBS treated?
Because IBS can cause a wide variety of symptoms, treatment must be tailored specifically to the individual.
Variation in bowel habit may respond to drugs that alter gut motility. For example, people with diarrhoea may find their symptoms improve with drugs that slow the bowels down. Conversely, people whose bowels tend towards constipation may respond to treatment with laxatives.
Abdominal pain can also be troublesome in people with IBS. Many painkillers are ineffective in IBS. Medicines to relieve pain in IBS may be directed at treating spasm in the bowel or may work by altering the way pain signals are transmitted by the nerves in the bowel.
Many people with IBS find that their symptoms can be triggered by food. Many also find that their condition can be improved by altering their diet. A Specialist Dietitian can help identify which foods are a problem, and can give advice about replacing them in the diet with acceptable alternatives. Our Australian dietician, Heidi Staudacher has extensive experience in this area, including a novel dietary intervention developed in Melbourne (low FODMAP diet - PDF 205kb) that is effective in reducing symptoms in many people with IBS. It involves reducing the amount of fermentable sugars in the diet, and is almost impossible to achieve without dietician guidance.