Inflammatory Bowel Disease
There are two forms of idiopathic inflammatory bowel disease
(IBD): ulcerative colitis
, a mucosal inflammatory condition confined to the rectum and colon, and Crohn’s disease, a transmural inflammation of gastrointestinal (GI) mucosa that may occur in any part of the GI tract. The etiologies of both conditions are unknown, but they may have a common pathogenetic mechanism.
- The major theories of the cause of IBD involve infectious or immunologic causes. Microorganisms are a likely factor in the initiation of inflammation in IBD. The immunologic theory assumes that IBD is caused by an inappropriate reaction of the immune system (both autoimmune and nonautoimmune phenomenon) Proposed etiologies for IBD.
- Smoking appears to be protective for ulcerative colitis but associated with increased frequency of Crohn’s disease.
- Ulcerative colitis and Crohn’s disease differ in two general respects: anatomic sites and depth of involvement within the bowel wall. There is, however, overlap between the two conditions, with a small fraction of patients showing features of both diseases