What is Inflammatory Bowel Disease?
Inflammatory bowel disease (IBD) is chronic inflammation of the bowels, mainly the large intestine, due to an immune reaction. It should not be confused with irritable bowel syndrome (IBS) which is a functional bowel condition of unknown cause. The bowels comprise the small intestine and large intestine which are jointly the largest parts of the alimentary tract. The large intestine is made up of the caecum, colon and rectum. IBD mainly affects the colon and often includes the rectum or ileum, which the last part of the small intestine. Rarely some types of IBD can affect any part of the alimentary tract including the mouth and stomach.
There are two major types of inflammatory bowel disease known as Crohn’s disease and ulcerative colitis. These conditions generally persist for life once it starts and may be associated with an increased risk of colon cancer. Both Crohn’s disease and ulcerative colitis are characterised by acute episodes of diarrhoea (runny tummy) and other gastrointestinal symptoms. This is known as the acute or active phase of the disease. Patients experience long periods of no symptoms (asymptomatic) or very mild symptoms which are referred to as the remission phase.
What is Crohn’s Disease?
Crohn’s disease is a type of inflammatory bowel disease that may occur anywhere in the gastrointestinal tract but typically affects the colon and ileum. It is characterized by patches of inflammation (skip lesions) that typically involves the entire thickness of the bowel wall causing deep narrow ulcers.
What is Ulcerative Colitis?
Ulcerative colitis is the more common type of inflammatory bowel disease and is isolated to the rectum and varying parts of the colon. The inflammation is generally extensive and isolated to the superficial layers of the bowel wall – mucosa and submucosa. Ulcers are usually broad and shallow.
Causes of Inflammatory Bowel Disease
The exact cause of inflammatory bowel disease is unknown. Since it tends to run in families, there is an indication that it is due to a genetic susceptibility. Specific genes have been isolated in both ulcerative colitis and Crohn’s disease patients but the the exact mechanism of how and why this disease develops is still unclear. There are several theories relating to the mechanism in inflammatory bowel disease and it is now believed that a combination of all these mechanisms may explain IBD.
A defective immune response appears to be the underlying factor in inflammatory bowel disease. The normal healthy bowel wall has a mucosal immune response which allows it to fight off any infection that may arise with contaminants in the gut. This mucosal immune response seems to be prematurely activated in IBD patients and this causes inflammation. In addition, it appears that the bowel wall has a defective immune response elicited by the natural bacteria in the bowels.
Symptoms of Crohn’s Disease and Ulcerative Colitis
Diarrhoea is the main symptoms of both Crohn’s disease and ulcerative colitis. In Crohn’s disease this is a watery large volume diarrhoea with no blood or mucus in the stool. Ulcerative colitis presents with a bloody diarrhoea and stringy mucus. Abdominal pain is more prominent in Crohn’s disease and is worse with eating meals and passing stool but pain is only seen in the toxic stages of ulcerative colitis (fulminant disease). Weight loss is also a noted feature in Crohn’s disease but not as significant, if at all present, in ulcerative colitis. Both Crohn’s disease and ulcerative colitis patients are likely to experience intestinal cramps.
Inflammatory bowel disease also presents with extra-intestinal features. This means that other signs and symptoms may be present which are either generalized or affect other organs apart from the bowels. Some of these features includes joint pains, skin rashes, inflammation of the eye, mouth sores, fever, malaise and lethargy.
Treatment for Inflammatory Bowel Disease
Inflammatory bowel disease is first treated and managed with medication. Depending on the severity of the disease and non-responsive nature to medication, surgery may also be considered.
Drugs to treat diarrhoea, intestinal cramping and abdominal pain are needed for acute episodes. These drugs should only be used in the short term and are not advisable for very severe episodes as it can aggravate the condition and lead to complications. Chronic management of IBD with medication involves a step-wise approach to treatment. When each step fails to yield the desired results, the medication of the next step are then utilised.
First, drugs known as aminosalicylates (anti-inflammatory medication) and antibiotics are used (step I) for treating IBD. However, antibiotics are of limited value in ulcerative colitis because it can lead to a condition known as pseudomembranous colitis. The next step (step II) involves the use of steroid drugs (corticosteroids) which are useful in shifting the condition into remission. Corticosteroids cannot be used long term due to the host of side effects associated with this disease. Lastly drugs known as autoimmune modifiers and TNF (tumour necrosis factor) inhibitors are used (step III) if the medication in step I and step II are ineffective. Step III drugs are immune suppressants and inhibits the body’s natural immune response.
Surgery is curative for ulcerative colitis and considered when medication is ineffective for management. Surgical procedures may remove the rectum and/or colon (proctocolectomy) with an opening created for a stoma bag (ileostomy). Another procedure removes the colon and/or rectum and joins the last part of the small intestine(ileum) to the anus (ileoanal anastomosis).
In Crohn’s disease, surgery is not curative but helps in the overall management of the condition with medication after the procedure. Diseased portions of the bowel are removed and the healthy sections surgically joined (ileorectal or ileocolonic anastomosis).