What are they?
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.
The diagnosis of an inflammatory bowel disease (IBD) is primarily made with non-laboratory tests, but laboratory testing is an important tool for ruling out other causes of diarrhoea, abdominal pain, and colitis (inflammation of the colon). These causes can include viral or bacterial infections, parasites, medicines, abdominal or pelvic radiation, colon cancer, and a variety of other chronic conditions such as coeliac disease and cystic fibrosis.
Laboratory Tests
Tests that may be requested to exclude other causes of diarrhoea and inflammation include:
- Stool culture to look for bacterial infection
- Ova and parasite examination of the stool
- Clostridium difficile to detect toxin created by bacterial infection; may follow antibiotic therapy
- Stool white blood cell count (WBC) to detect the presence of WBC
- A screen for Coeliac disease tests
Tests that are not specific for IBDs but help to distinguish them from non-inflammatory causes of diarrhoea such as irritable bowel syndrome (IBS) include:
- White blood cell count as part of a full blood count (which also checks for anaemia)
- ESR (erythrocyte sedimentation rate)
- CRP (C-reactive protein)
- Faecal calprotectin
Calprotectin is a protein found in cells associated with inflammation. It is the most abundant protein present in neutrophils (white cells blood cells), and is released from these cells when they die.
The concentration of calprotectin in faeces correlates with the level of bowel inflammation present. The concentration of faecal calprotectin therefore tends to be increased in IBD (a disease characterised by inflammation), but not in IBS (Irritable bowel syndrome, a disease which is not characterised by inflammation). A negative faecal calprotectin result supports the diagnosis of IBS.
In October 2013 the National Institute for Health and Care Excellence (NICE) recommended that faecal calprotectin testing could be used to support clinicians in differentiating IBD from IBS. Importantly, faecal calprotectin analysis may avoid the need for more invasive tests (such as endoscopy) to distinguish between these two disorders.
Calprotectin may also be useful to help monitor IBD and alert your doctor to a flare-up.
Non-Laboratory Tests
These tests are used to help diagnose and monitor IBDs. They can be used to look for characteristic changes in the structure and tissues of the intestinal tract and to detect blockages. Care must be taken during an acute attack or flare-up of an IBD as there is a slight chance of perforating the bowel during testing.
- Barium meal and follow through: after swallowing barium contrast dye, abdominal Xrays picture the small intestine
- Sigmoidoscopy: a slender tube is used to examine the last two feet of the colon
- Colonoscopy: a slender tube is used to examine the entire colon; it includes a light and camera and can be used to take biopsies
- Capsule endoscopy: may be used in selected patients. A small pill shaped camera is swallowed so that it travels through the digestive system. The camera records images of the digestive tract which can be viewed by the doctor.
- Biopsy: tissue samples taken from the colon are evaluated for inflammation and abnormal changes in cell structure
Treatment of inflammatory bowel diseases is targeted at reducing inflammation, relieving symptoms such as pain and diarrhoea, controlling and healing damage where possible, identifying and addressing complications, and supplementing any nutritional shortages. Since the course of an IBD is usually one of flare-up followed by remission, the treatment often changes over time.
Patients with Crohn’s disease or ulcerative colitis need to be regularly monitored and should work with their doctors to become educated about their condition. While lifestyle changes, such as diet modification, rest and stress reduction, may help improve a patient’s quality of life and extend a remission, they cannot prevent an IBD flare-up. Acute symptoms are treated with a variety of medicines. These drugs are effective but many can only be given for short periods of time because of their side effects.
Current therapies include the use of, anti-inflammatory drugs, steroids (to control and to suppress inflammation), immunosuppressive drugs, and antibiotics. Infliximab, an anti-TNF monoclonal antibody with potent anti-inflammatory effects, may be used in active, fistulating Crohn’s disease if other treatment options have not worked. In addition to drug treatment, one or more surgical procedures may become necessary to remove damaged tissue, to treat fistulae or to relieve obstruction. Guidance on the use of treatments in the management of patients with Crohn’s disease was published by the National Institute of Health and Clinical Excellence (NICE) in October 2012.