Crohn’s disease is a chronic inflammatory condition that most commonly affects the last segment of the small intestine (ileum) and the first part of the large intestine (caecum), although it can occur in any part of the GIT from the mouth to the anus. It is not uncommon for people with Crohn’s disease to have normal, healthy parts of tissue in between areas of inflammation. This has implications for how Crohn’s disease is treated, especially by surgery. Also, unlike ulcerative colitis, where the inflammation is limited to the innermost lining of the intestinal wall, in Crohn’s disease the inflammation can extend into the deeper layers, which can lead to the development of complications that are quite specific to the condition.
How does Crohn’s disease affect the intestines?
Crohn’s disease affects the GI tract, and the intestinal wall becomes inflamed (red and swollen). The inflammation can penetrate through all layers of the GI tract and may occur at one or more locations in the GI tract, from the mouth right through to the anus, with areas of normal tissue between areas of diseased tissue. Depending on the main areas of the intestine involved in Crohn’s disease, the condition can be referred to as:
- Ileocolitis: involves the ileum and colon (small and large intestine)
- Ileitis: involves the ileum only (small intestine only)
- Crohn’s (granulomatous) colitis: involves the colon only (large intestine only)
- Gastroduodenal Crohn’s disease: involves the stomach and duodenum (small intestine)
- Jejunoileitis: involves the jejunum (small intestine only)