“ Nature is pleased with simplicity” Isaac Newton

What is Crohn's Disease? Crohn's disease (named after an American doctor - Burrill Crohn - who described the condition in 1932) is an inflammatory condition of the gastrointestinal tract. It can affect any part from the mouth to the anus, but the most common site is where the small intestine joins the colon (the 'terminal ileum'), and the colon itself. Unlike ulcerative colitis - which only affects the colon - it can occur in separate patches and can involve the entire thickness of the bowel wall. About 1:1000 - 1:10,000 people are affected, and it presents at any age, but most commonly in late teens, early twenties and late middle age. Smoking is a significant risk factor for the development of Crohns disease, makes the condition more difficult to treat and is associated with a higher risk of requiring an operation. There is a strong genetic component, and to date over 160 genes have been found that are involved with the development of Crohns Disease.

What are the symptoms of Crohn's Disease? As Crohn's disease can affect any part of the gastrointestinal system, it can lead to a wide variety of symptoms. The commonest presentation is with abdominal pain (often in the lower right hand side) and diarrhoea with or without bleeding. Symptoms can be present in a mild form for some time before the diagnosis becomes apparent. Low level chronic inflammation can lead to scarring and narrowing of a segment of intestine which can result in a partial blockage - resulting in distension, pain or vomiting - as the presenting symptoms.
Some patients just present with disease around the bottom leading to absecess or connections between the internal bowel and the skin (a 'fistula'). Such connections or tracks are an uncommon but unpleasant complication of Crohns disease and can occur between internal organs or the intestine and the skin. It is not uncommon also to experience symptoms outside the gastrointestinal tract with joint pains, irritation of the eye, or skin rashes.

What causes Crohn's Disease? The cause of Crohns disease is not known, but the recent discovery of an association with certain genes has helped us to understand the pathways involved. There appears to be a primary defect of immunity within the gut which leads to an inability to clear infection and an exaggerated inflammatory response. Only minor defects of immunity are apparent outside the gut so an increased risk of general infections is not associated with the condition. Whilst many individual bacteria have been implicated in the past, it does not currently appear as though a single type of bacterium is involved in the response.

How is Crohn's Disease diagnosed? The condition is diagnosed on the basis of symptoms, raised inflammatory markers in the blood and stool ('faecal calprotectin'), characteristic findings on imaging techniques - X-ray or magnetic resonance scans - and most importantly by findings at endoscopy and by microscopic examination of tissue biopsies taken at endoscopy. The diagnosis can sometimes be challenging as there are several conditions - including some infections - that can give similar appearances at times.

What treatment is available for Crohn's Disease? The treatment of Crohns disease depends on the manner of its presentation. Drugs to suppress the immune system - and thereby the inflammation in the gut - are the mainstay of treatment and include steroids, thiopurines (Azathioprine, 6-Mercapto purine), methotrexate and potent monoclonal antibodies against inflammatory molecules (anti-TNF agents). In mild or moderate cases, treatment can sometimes be initiated by using a liquid diet. Nobody knows quite why this works - although it may affect the bacterial populations living in the gut.

Does Crohn's Disease require an operation? Surgery is often required in Crohns disease as chronic inflammation in a segment of intestine can lead to scarring that leads to narrowing. Surgery is performed much less frequently than in the past as it is well known that the disease recurs where the intestine has been rejoined. It is often possible to treat patients effectively with newer drugs and postpone or avoid surgery. The commonest type of operation required for Crohn's disease - removal of a short segment of intestine where it joins the colon - can usually be performed without the need for a stoma ('bag') and often nowadays by 'keyhole' surgery leaving only small scars on the abdominal wall.

What is the long term course of Crohn's Disease? Again this depends very much on what part of the gut is affected by the condition and how severe the condition is. The majority of patients with Crohns disease require some form of medication to keep the inflammation at bay. 60-75% of patients with disease affecting the terminal ileum require an operation at some stage - but this proportion may be declining with recent advances in medical treatment.

What resources are available? The national UK charity for inflammatory bowel disease - Crohns and Colitis UK - have a useful and informative website.

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