What is inflammatory bowel disease, and what are its two main forms?

Inflammatory bowel disease (IBD) comprises idiopathic, chronic, relapsing-remitting intestinal inflammation. The two main forms are ulcerative colitis (UC) and Crohn's disease (CD).

Clinical relevance. Recognising IBD as two distinct chronic relapsing diseases frames the whole approach to diagnosis and treatment.

More Detail

Inflammatory bowel disease

IBD is a group of chronic immune-mediated inflammatory disorders of the gut of unknown cause.

Definition

• Idiopathic chronic intestinal inflammation with a relapsing and remitting course.

The two main forms

• Ulcerative colitis (UC): continuous mucosal inflammation of the rectum and colon.
• Crohn's disease (CD): patchy transmural inflammation that can affect any part of the gut from mouth to anus.

General features

• Both are commonest in Caucasians, usually diagnosed in young adults, and carry an increased risk of colorectal cancer.
• A subset of colitis cannot be classified and is termed IBD-unclassified (indeterminate colitis).