Inflammatory bowel diseases (IBD) are chronic disorders that affect approximately 1 in 350 people in the UK. Characterised by swollen and damaged tissues in the lining of the intestinal tract, these conditions vary in severity from patient to patient and change over time. During a flare-up, a patient may experience frequent bouts of watery and sometimes bloody diarrhoea, abdominal pain, weight loss and fever. Between these flare-ups symptoms frequently diminish. Many patients may go through extended periods of remission before another flare-up occurs.
The cause of IBD is not known, but these diseases are thought to be due to an autoimmune process that has been triggered by a viral illness or an environmental factor in persons with a genetic predisposition. IBD affects slightly more women than men and is seen most frequently in Caucasians who live in industrialised countries. The most common inflammatory bowel diseases are Crohn’s disease and ulcerative colitis. In the UK, ulcerative colitis is twice as common as Crohn’s disease. Both diseases can start at any age, but the majority are first diagnosed in patients between the ages of 15 and 30 and a smaller number between 60 and 80. Children affected by either disease may experience delayed development and growth retardation in addition to gastrointestinal symptoms.
A serious complication of these disorders is toxic megacolon. Toxic megacolon is a rare condition, arising due to severe inflammation and paralysis of a section of colon. This leads to rapid dilation (widening) of the colon, which can cause abdominal pain, fever, and weakness. It is life threatening condition if left untreated.
Patients who are diagnosed with IBD at a young age are also at an increased risk of developing colon cancer later in life.
Crohn’s disease can affect any part of the gastrointestinal tract from the mouth to the anus, but is most commonly found in the last part of the small intestine (the ileum) or the colon (large intestine). Intestinal tissue may be affected in patches with normal tissue in between. Over time the inflammation caused by the Crohn’s disease can damage the digestive tract. This may cause narrowing of the colon, ulcers (painful sores on lining of intestine) or fistulae (tunnels through the intestinal wall into another part of the gut or another organ). Other complications of Crohn’s disease include bowel obstruction, anaemia from bleeding tissue, and infections. About 80% of patients with Crohn’s disease require surgery at some stage, either to remove damaged sections of the intestine or to treat an obstruction or fistula.
Ulcerative colitis primarily affects the surface lining of the colon. Although the symptoms may be similar to those seen with Crohn’s disease, the tissue inflammation is continuous, not patchy, and usually starts from the anus and extends up the colon. Ulcerative colitis tends to present more frequently with bloody diarrhoea.
About 5% of patients with IBD affecting the colon cannot be classified because they have some clinical, radiological, endoscopic and pathological features of both Crohn’s disease and ulcerative colitis.
Inflammatory bowel disease is not the same as irritable bowel syndrome (IBS). IBS is a more common but poorly understood condition that causes symptoms such as bloating, abdominal discomfort, and change in bowel habits (diarrhoea and/or constipation). IBS is not associated with inflammation or change in structure of the bowel.