Inflammatory bowel disease (IBD) is the general name for ulcerative colitis and Crohn's disease. The disease is characterized by swelling, ulcerations, and loss of function of the intestines.
The primary problem in IBD is inflammation, as the name suggests. Inflammation is a process that often occurs to fight off foreign invaders in the body, including viruses, bacteria, and fungi. In response to such organisms, the body's immune system begins to produce a variety of cells and chemicals intended to stop the invasion. These immune cells and chemicals, however, also have direct effects on the body's tissues, resulting in heat, redness, swelling, and loss of function. No one knows what starts the cycle of inflammation in IBD, but the result is a swollen, boggy intestine.
In ulcerative colitis, the inflammation affects the lining of the rectum and large intestine. It is thought that the inflammation typically begins in the last segment of large intestine, which empties into the rectum (sigmoid colon). This inflammation may spread through the entire large intestine, but only rarely affects the very last section of the small intestine (ileum). The rest of the small intestine remains normal.
Crohn's disease is a form of IBD that affects both the small and large intestines. The inflammation of ulcerative colitis occurs only in the lining of the intestine (unlike Crohn's disease which affects all of the layers of the intestinal wall). As the inflammation continues, the tissue of the intestine begins to slough off, leaving pits (ulcerations) that often become infected.
IBD can occur in all age groups, with the most common age of diagnosis being 15–35 years of age. Men and women are affected equally. Whites are more frequently affected than other racial groups, and people of Jewish origin have three to six times greater likelihood of suffering from IBD. IBD is familial; an IBD patient has a 20% chance of having other relatives who are fellow sufferers.
Belinda Rowland, The Gale Group Inc., Gale, Detroit,