Inflammatory Bowel Disease



Introduction

The term inflammatory bowel disease (IBD) refers to both Crohn’s disease (CD) and Ulcerative colitis (UC). Both conditions involve inflammation involving the gut (gastrointestinal tract). In around 5-10% of patients the inflammation is difficult to diagnose as Crohn’s or U.C and therefore, the term ‘indeterminate’ colitis is used.

The cause of IBD is unknown, however, there are a number of possible theories. Both conditions are thought to be multi-factorial with both genetic and environmental involvement.  It is estimated that there are 200,000 people in the United Kingdom with IBD, of which approximately 120,000 people have U.C and 60-80,000 with Crohn’s disease.

Does IBD run in families?

A 1st degree relative of a patient with UC has a 10-15 fold increased risk of developing UC, which is roughly a 1 in 20 chance of developing the condition.  For Crohn’s disease there is an estimated 10 fold increased risk of developing crohn’s disease if a 1st degree family relative had Crohn’s disease.

Ulcerative Colitis

U.C is an inflammatory condition of the lining of the large bowel. Usually it is continuous inflammation running from the rectum extending proximally in to the colon. The inflammation is confined to the colon.

Clinical symptoms include rectal bleeding, diarrhoea and sometimes abdominal pain.  The diagnosis is based on the clinical history, endoscopic and analysis of biopsy specimens (tissue from colon). At endoscopy (colonoscopy/ flexible sigmoidoscopy) the findings can range from mild inflammation to severe ulceration in the colon and rectum.

Treatment

There are a number of treatments available for the management of UC this include anti-inflammatory agents (5-aminosalicylic acid).

5-Aminosalicylate acid

These agents can be taken orally as tablets or per rectum. If the disease only affects the rectum, the condition is termed proctitis. First line treatment for this condition is 5-aminosalicylate (5-ASA) suppository.

Steroids

Steroids can be very good at inducing remission in the short term. The most common steroid used is prednisolone, a course of prednisolone lasts around 8 weeks.

Immunosuppressant

There are a number of immunosupressants that are used in UC, these include azathioprine, 6-mercaptopurine, ciclosporin, methrotrexate and mycophenolate mofetil. The most commonly used agents are azathioprine and 6-mercaptopurine.
Prior to starting this treatment your doctor will need to discuss with you the risks and benefits.

Biologics therapy

 Biologic agents are designed to target specific points in the inflammatory process. The two commonly used agents in IBD are Infliximab and adalimumab. These agents target a protein in the body called TNF-alpha (tumour necrosis factor-alpha). Your body naturally produces TNF-alpha as part of its immune response, to help fight infections by temporarily causing inflammation in affected areas. Over-production of this protein is thought to be partly responsible for inflammation in the intestine of people with IBD. Infliximab binds to TNF-alpha, helping to prevent inflammation and relieve symptoms.



Crohn’s disease (CD)

Crohn's disease can affect the whole gastrointestinal tract from mouth to anus. It appears different under the microscope to UC.

It most commonly it affects the end of the small bowel (terminal ileum) and colon. However, patients can develop disease in multiple sites. The nature of the inflammation is different to UC, it can cause inflammation at all levels of the bowel wall. Inflammation around the anus can cause fistulation (tracts communicating bowel with skin or other internal organs) which can lead to a great deal of discomfort. Ongoing inflammation in the bowel can also cause stricturing, leading to blockages and indeed fistulation out of the bowel itself.

Clinical symptoms can be varied dependent on the site of disease. As with UC diagnosis is based on taking a through clinical history, endoscopic and microscopic findings. In addition due to the location of disease other tests may be required, these include CT scan, MRI enterography, small bowel capsule endoscopy and barium small bowel follow through studies.

Treatment

Treatment of Crohn’s disease uses similar medications to UC, however, there may be a role elemental diet in patients with small bowel disease.

Further information

Crohn's and Colitis UK