What is Inflammatory Bowel Disease (IBD)?

Illustration of gut

IBD is common affecting approximately 1 in 200 people in the United Kingdom.

There are two main forms of Inflammatory bowel disease (IBD), Crohn’s disease (CD) and ulcerative colitis (UC). These are lifelong relapsing conditions commonly presenting in the teens and twenties. These diseases are common, affecting approximately 1 in 200 people in the United Kingdom with men and women are equally affected. The cost to the NHS of managing patients with IBD has been estimated at about £720 million, based on the prevalence and an average cost of £3,000 per patient per year.

Clinical effects

The diseases cause inflammation and ulceration in the colon and rectum (ulcerative Colitis) or anywhere in the gastrointestinal tract (Crohn’s Disease).  Both conditions can produce symptoms of urgency, diarrhoea, abdominal pain, and profound fatigue.

Some patients have additional symptoms from associated inflammation of the joints, skin, liver or eyes.   Malnutrition and weight loss are common with patients often altering their eating habits to alleviate symptoms. When diagnosed in childhood the disease is often more severe than if presenting in adulthood, with major consequences on life long health. IBD follows an unpredictable relapsing and remitting course with significant variation in the pattern and complexity of the symptoms both between patients and in the individual patient at different times in his or her illness.

Complications of IBD

The inflammation in Crohn’s Disease may lead to strictures (narrowing) of the bowel resulting in abdominal pain due to partial blockage. Severe cases may lead to life-threatening complications such as complete blockage or perforation of the bowel. Crohn’s Disease is often associated with anal problems such as fissure, tags, abscess and fistula formation.

There is an established link between IBD and an increased risk of developing colorectal cancer. The risk of colorectal cancer increases with the extent and severity of the disease, the age of onset and duration of the disease. For patients suffering from ulcerative Colitis, the risk of colorectal cancer at 10, 20 and 30 years after the onset of the disease to be 2, 8 and 18% respectively.


The precise causes of both Crohn’s Disease and Ulcerative Colitis remain unknown although the current hypothesis is that disease results from an inappropriate (either over or underactive) response of an individual’s immune system to bacteria which we all harbour in our gut.   There is a genetic predisposition which increases the risk of IBD tenfold in first degree relatives of an IBD patient and which probably determines the pattern and severity of the disease in any individual patient. To date more than 90 IBD genes have been identified. Much research is focused on understanding the role of bacteria in the gut and the many different parts of the immune system’s response to external triggers.  It seems quite likely that the trigger for the disease varies between individuals.


Aminosalicylates (5ASA), corticosteroids and immunosuppressive drugs are the mainstay of medical management for inducing and maintaining remission.  They alleviate symptoms but the extent to which they alter the natural course of the disease remains unclear. 30% of patients will fail to respond to these drugs or be intolerant of them and these patients may then be considered for anti-TNFα biological therapies or surgery.

Between 50% and 70% of patients with Crohn’s Disease will undergo surgery within 5 years of diagnosis. In Ulcerative Colitis lifetime surgery rates are up to 20% for ulcerative Colitis although rates for colectomy vary between countries and regions. The most common forms of surgery for patients with Crohn’s disease are removal of the diseased part of the small bowel, with or without part of the colon. The formation of a stoma may be required and this may be permanent. For people who have Ulcerative Colitis, restorative proctocolectomy is the commonest operation. This involves removal of the colon and rectum, combined with the fashioning of an ileal pouch. This is made from the terminal ileum and joined to the anus to form a reservoir which replaces the rectum, thus avoiding a permanent stoma.

Psycho-social effects

Education, working, social and family life are all disrupted by the unpredictable occurrence of flare-ups.  The frequent and urgent need for the toilet (up to 20 times per day is common), together with loss of sleep and the invisible symptoms of pain and continual or profound fatigue, can severely affect self-esteem and social functioning and quality of life  particularly among the young and newly-diagnosed. However with effective management many patients will be able to lead a rewarding and productive life within the constraints imposed by the condition.