Crohn's disease explained

Crohn's disease is an inflammatory bowel diseaseA group of inflammatory conditions of the intestine. The two major forms are Crohn’s disease and ulcerative colitis., a group of conditions that includes both Crohn's disease and ulcerative colitis. The exact cause of Crohn's disease is not yet known, but it probably results from the influence of environmental factors on the lining of the intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus. in genetically susceptible people.

Crohn's disease is named after Dr Burrill B. Crohn who first described it in 1932, although the disease had been recognised by doctors many years before that.

  • Inflammation can occur in any part of the digestive system, from the mouth to the anusThe external opening of the back passage, the rectum.. The most commonly affected parts are the small intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus. and the large intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus., which is also known as the colonThe large intestine.
  • The entire thickness of the intestinal wall is usually inflamed. The inflammationThe body’s response to injury. often occurs in patches
  • Crohn's disease can be classified according to which part of the gastrointestinal tractThe gut, which begins at the mouth and ends at the anus. is affected
  • The symptoms of the disease can vary from person to person
  • About half of all cases have only mild symptoms
  • The most common pattern is to have a period of good health, interrupted by episodes during which the symptoms get worse, also known as 'flare-upsTerm to describe episodes when the symptoms of a condition worsen.'
  • Periods of remission when the disease is fully controlled can last for years
  • The disease may cause complications such as narrowing of sections of the intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus., known as strictures, the formation of abnormal channels called fistulae, and local infections, or abscesses, in the gastrointestinal tractThe gut, which begins at the mouth and ends at the anus..

I remember a great deal of pessimism when I was first diagnosed - one doctor told me I would suffer with stomach pains constantly for the rest of my life! It can be awful to be on the receiving end of news like that. And his prognosis hasn't been true.

I remember a great deal of pessimism when I was first diagnosed - one doctor told me I would suffer with stomach pains constantly for the rest of my life! It can be awful to be on the receiving end of news like that. And his prognosis hasn't been true. I'm now living a full life. I can eat what I want, within reason. I work in a job I love, travel wherever I want and have been in remission for years. Emma

Classification of Crohn's disease

Crohn's disease can be classified according to which part of the gastrointestinal tractThe gut, which begins at the mouth and ends at the anus. is affected. The types are listed in the order of how common they are as follows:

  • Ileocolitis affects the ileumThe last part of the small intestine., which is the lowest part of the small intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus., and the colonThe large intestine. or large intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus.
  • Ileitis affects the ileumThe last part of the small intestine.
  • Crohn's colitis (granulomatous colitis) is limited to the large intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus.
  • Gastroduodenal Crohn's disease is very rare, and affects the stomach and duodenum
  • Jejunoileitis is also very rare, and produces patchy areas of inflammationThe body’s response to injury. in the jejunum, which is the middle part of the small intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus. between the duodenum and ileumThe last part of the small intestine..

Complications of Crohn's disease

Crohn's disease can lead to several complications, such as strictures, fistulae and abscesses.

  • A stricture is a narrowing of the intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus. as a result of inflammationThe body’s response to injury. and scarring. This can lead to blockages of the gastrointestinal tractThe gut, which begins at the mouth and ends at the anus., which can be dangerous and can cause pain and constipation
  • Fistulae are abnormal channels that develop between parts of the body, or between the body and the outside. In Crohn's disease, fistulae may develop between an inflamed part of the intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus. and another part of the intestineThe section of gut, or gastrointestinal tract, from the stomach to the anus., another organ in the abdomenThe part of the body that contains the stomach, intestines, liver, gallbladder and other organs., or the skin. These can form pockets of infectionInvasion by organisms that may be harmful, for example bacteria or parasites. or abscesses.