Crohn’s disease (CD) is a chronic inflammatory condition that can affect any part of the gastro-intestinal tract – from the mouth to the anus. It most commonly affects the last part of the small bowel and first part of the colon (large bowel). It may vary in severity – from not requiring specific treatment to treatment-refractory disease. Early effective therapy is vital in preventing long-term complications.

Symptoms

• Diarrhoea
• Abdominal pain
• Blood in the stools
• Weight loss
• Growth retardation in children
• Oral ulcers
• Peri-anal disease e.g. fissures, fistulas

Diagnosis

As with ulcerative colitis, the diagnosis of Crohn’s disease  is suspected based on the history and clinical picture. It is then confirmed by colonoscopy or radiological investigations (e.g. CT scan or MRI) and excluding conditions that mimic it. Tuberculosis is the condition most commonly confused with Crohn’s disease, as the two may be virtually indistinguishable. This is of special concern as the treatment of Crohn’s disease will make infection with tuberculosis much worse.

Complications

In severe or untreated cases of Crohn’s disease complications may develop that require surgery to correct. These include strictures, fistulas, abscesses or colorectal cancer:

• Strictures are caused by inflammation in the wall of the bowel. This inflammation results in scarring and subsequent narrowing of the bowel.
• Fistulas are tracts connecting one body cavity with another. They are also as a result of inflammation and are usually related to strictures. A fistula can connect one section of bowel to another, or can even cause a connection between the bowel and the bladder, vagina or skin surface (amongst others).
• An abscess forms when a fistula penetrates the bowel wall and causes leakage of bowel contents into the abdominal cavity.
• Patients with Crohn’s disease involving the colon which is present for more than ten years are at increased risk of developing colorectal cancer. Their risk should be assessed and they should be surveyed appropriately.

Treatment

The treatment for Crohn’s disease is not curative. It usually consists of immunosuppressive medications, but sometimes surgery is required in severe cases. Medication use is usually lifelong and should be managed by a gastroenterologist. 5-ASA agents used in ulcerative colitis are rarely very effective and immunosuppression is recommended in all but mild cases of Crohn’s disease.

Immunosuppressant agents weaken the immune system and so reduce the immune-mediated inflammation in the bowel. Because of this, they also make the body susceptible to certain infections. Immunosuppressant therapy should only prescribed by a doctor trained in their use. In the context of Crohn's disease, this should only be a gastroenterologist.