Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a collection of symptoms that together are labelled as a diagnosis. These symptoms include abdominal pain, bloating, diarrhoea and constipation. IBS is a very common condition, affecting up to one in four people, most of whom have mild symptoms. The main types of IBS are where constipation is predominant (IBS-C), where diarrhoea is predominant (IBS-D), and where diarrhoea and constipation alternate (IBS-A).

Although anyone can get IBS, some subgroups of people seem to be more prone to the disorder. Research is still a long way away from defining what IBS actually is, but there does seem to be an increased occurrence after a bout of gastroenteritis or a traumatic life event. There is also an association with chronic pain syndromes, chronic fatigue syndromes, and fibromyalgia.

Recent research suggests that there are multiple causes of IBS, with some causes probably yet to be identified. It appears that one in 10 cases of IBS are likely to have been triggered by gastroenteritis. In sensitive individuals, it seems that the damage caused by gastroenteritis allows bacteria that normally live in the gut to damage the bowel lining. This results in increased permeability (leakiness) of the gut membrane, which may cause mild inflammation of the bowel. This trigger of IBS can get better with time, but in a few it’s an ongoing problem.

Stress is often said to be a cause of IBS. However, this does not mean that reducing stress can improve IBS. It is probable that certain psychological traits are associated with conditions that can lead to IBS. Therefore, the widely held belief that reducing stress levels can improve IBS is probably incorrect.

Malabsorption of bile salts is the cause of IBS in one third of people with diarrhoea-predominant IBS. It is thought that bile salts are normally totally absorbed in the small bowel, but may cause irritation and diarrhoea if they enter the large bowel.

Bacterial overgrowth in the small bowel is another known cause of IBS. Bacteria are normally found in the large bowel and to a lesser degree in the small bowel. On a microscopic level, we know that the gut wall develops low-level inflammation to counter the bacterial load and toxins within the interior of the gut. There are 1000 –2000 different types of normal bacteria living in the gut and a decrease in numbers of these may allow levels of some bacteria that cause symptoms to increase. Unfortunately, some people seem to have more bacteria within the small bowel and this can result in inflammation and IBS-like symptoms.

Overall, it seems that is not just one cause of IBS, and IBS may in fact turn out to be an umbrella term for numerous different conditions. Some people are fortunate and only have IBS for a short time or their symptoms are very minor. However, others have a very difficult time with IBS throughout their lives. These people may have other severe conditions as well, and their quality of life can be very poor indeed.

The common triggers for IBS, including certain food items, antibiotics, acute gastrointestinal illness, and stressful life events, are not necessarily causal, and more likely to be the “final straw” in an individual with a predisposition to IBS and who was likely already on the verge of developing symptoms of IBS.


There is no specific test that can diagnose IBS. The symptoms of IBS overlap with those of more serious conditions affecting the bowel, such as coeliac disease, inflammatory bowel disease, and colon cancer. Any change in bowel habit warrants a prompt visit to a colorectal specialist, whose job it is to exclude other potentially serious causes of your symptoms.

My interest in IBS started many years ago when I came to realise that treating pelvic pain in isolation would not help my patients and that an in-depth understanding of both pelvic pain and IBS was needed. I therefore made contact with some of the best minds in these fields in the country and have learned from them. I can now confidently manage both pelvic pain and IBS.

I work very closely with a gastroenterologist specialising in IBS and dieticians who are experts in functional bowel disease as well as the FODMAP diet (

As a colorectal surgeon, my priority is to exclude serious conditions such as cancer and inflammatory bowel disease in my patients. However, I never discharge patients whom I believe to have IBS – I do my best to identify reasons for their symptoms and manage them until their quality of life improves to an acceptable level.

If you would like more information on IBS, you may find the following websites very helpful: and

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