What is Inflammatory Bowel Disease (IBD)?
IBD is the combined term used to describe two different chronic inflammatory conditions of the gastrointestinal tract – ulcerative colitis (UC) and Crohn’s disease. In a minority of patients it is uncertain which type is present and the term ‘indeterminate’ or ‘IBD-unclassified’ is used.
What are the causes of inflammatory bowel disease?
Despite much research, the cause is still unknown but these conditions are thought to arise in people with an inherited susceptible immune system which reacts abnormally to an environmental agent – probably a strain or strains of usually harmless intestinal bacteria.
How common is IBD?
IBD is most common in industrialised countries and in the UK between 150,000 and 200,000 people are affected. The incidence of Crohn’s disease is increasing and ulcerative colitis is stable.
What are the symptoms of inflammatory bowel disease?
Ulcerative colitis (UC) causes inflammation of the superficial lining of the colon (large bowel) which results in diarrhoea and bleeding – the severity of which depends upon the amount of colon involved. The disease usually starts between the ages of 10 and 40 and the inflammation can resolve and recur at any time.
Up to a quarter of people with UC also develop inflammation in other organs including the joints, skin and eyes.
How is it diagnosed?
Blood and stool tests may be helpful at excluding other conditions which mimic UC (e.g. infections) and the diagnosis is made by examining the lining of the large bowel at colonoscopy.
How is it treated?
The treatment depends upon the severity of inflammation and on how much of the large bowel is inflamed.
For short periods, steroids (by mouth or as an enema) are usually very effective. Mesalazine (or 5-ASA) is an anti-inflammatory drug which is often effective and safe when given for long periods and can also be given by mouth or as an enema.
Immunosuppressants may be needed if the benefits (i.e. avoidance of repeated doses of steroids) are thought to outweigh the side-effects (i.e. reversible bone marrow suppression). Occasionally if the inflammation cannot be controlled with medication, surgery is needed to completely remove the large bowel. In a later operation, the small bowel is internally joined back to the anus.
What are the long term risks of ulcerative colitis?
There is a small increased risk of developing colon cancer – the risk increases with the duration and severity of the disease. For this reason a colonoscopy should be performed 8-10 years after the diagnosed and every few years thereafter. If abnormal cells are detected they can be removed or possibly surgery performed before a cancer develops.
What is Crohn’s disease?
Unlike UC, Crohn’s disease can cause inflammation in any part of the digestive tract, but most commonly at the end of the small intestine (terminal ileum) and colon. The inflammation spreads through the wall of the intestine and tends to be patchy.
The severity of disease is very variable and many people have relatively mild disease which hardly impacts on their life.
What are the symptoms of Crohn’s disease?
The symptoms depend upon which part of the digestive tract is involved and may be non-specific and be present for some time before the diagnosis is made. Cramping abdominal pain, weight loss and watery diarrhoea (blood diarrhoea is more common in UC) are most common. More severe inflammation leads to narrowing of the intestines (strictures), abscesses or fistula (small connections between the rectum and adjacent skin).
How is it diagnosed?
Initial investigations include blood and stool tests. A colonoscopy is needed to examine the large bowel and end of the small bowel and to take biopsies. If the diagnosis is still unclear, radiological tests (CT scan and/or MRI) are often helpful. Capsule endoscopy is increasingly used to detect inflammation in the small intestine which cannot be detected by conventional colonoscopy and radiology.
How is it treated?
Prednisolone (a steroid) usually works rapidly to reduce inflammation but cannot be used for long periods as it can cause weight, hypertension, osteoporosis and infections due to immunosuppression.
Unlike UC, stopping a normal diet and taking a liquid diet (polymeric or elemental) is often effective in the short-term.
Antibiotics are also used to treat abscesses and to temporarily reduce inflammation in the lining of the intestine.
Immunosuppressant medications (azathioprine, 6-mercaptopurine and methotrexate) are increasingly being used but take 2-3 months to start working and need regular monitoring with blood tests.
About half of patients with Crohns’ disease of the small intestine will need an operation at some stage. This usually means removing a limited section of the intestine or draing abscess or fistula in the rectum.
What are biological treatments for Crohn’s disease?
Biological treatments are antibodies designed to a block a specific part of the immune system. They are increasingly being used and most patients experience a rapid reduction in symptoms. They are usually used if repeated doses of steroids are needed or if immunosuppressant drugs are not working adequately.
The two agents commonly in use are infliximab (Remicaid®), which is given intravenously every 8 weeks, and adalimumab (Humira®) which is self-administered under the skin every 2 weeks. Close monitoring is needed as they can lower the immune system and cause infections.
Where can I find out more about Crohns disease?
The National Association for Colitis and Crohn’s disease (www.nacc.org.uk) is an easily accessible source of useful information.