Inflammatory bowel disease is a condition in which the innner lining of the GI tract becomes inflamed, leading to ulcers and bleeding. The colon is most often the site of this inflammation. Patients with inflammatory bowel disease have symptoms that include diarrhea, abdominal pain, infections, and bleeding. Inflammatory bowel disease falls under two main headings: Crohn's disease, which involves the entire GI tract, and ulcerative colitis, which involves only the colon. The cause of inflammatory bowel disease is unknown.