Inflammatory Bowel Disease Health Article

Definition

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.

Description

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.

Causes & symptoms

No specific cause of IBD has been identified. Although no organism (virus, bacteria, or fungi) has been found to set off the cycle of inflammation, some researchers continue to suspect that an organism is responsible. Other researchers are concentrating on identifying some change in the cells of the colon that would make the body's immune system accidentally begin treating those cells as foreign. Additional evidence for a disorder of the immune system includes the high number of other immune disorders that frequently accompany IBD. The condition has also been linked to physical, mental, and emotional stress.

The first symptoms of IBD are abdominal cramping and pain, a sensation of urgent need to have a bowel movement (defecate), and blood and pus in the stools.

Some patients experience diarrhea, fever, and weight loss. If the diarrhea continues, signs of severe fluid loss (dehydration) begin to appear, including low blood pressure, fast heart rate, and dizziness.

Severe complications of IBD include perforation of the intestine, toxic dilation (enlargement) of the colon, and the development of colon cancer. Intestinal perforation occurs when long-standing inflammation and ulceration of the intestine weaken the wall to such an extent that a hole occurs. This is a life-threatening complication, because the contents of the intestine (which contain a large number of bacteria) spill into the abdomen. The presence of bacteria in the abdomen can result in a massive infection called peritonitis.

Toxic dilation of the colon is thought to occur because the intestinal inflammation interferes with the normal function of the muscles of the intestine. This allows the intestine to become lax, and its diameter begins to increase. The enlarged diameter thins the walls further, increasing the risk of perforation and peritonitis. When the diameter of the intestine is quite large and infection is present, the condition is referred to as "toxic megacolon."

Patients with IBD have a significant risk of developing colon cancer. This risk seems to begin around 10 years after diagnosis. The overall risk of developing cancer seems to be greatest for those patients with the largest extent of intestine involved. The risk becomes statistically greater every year:

• At 10 years, the risk of cancer is about 0.5–1%.
• At 15 years, the risk of cancer is about 12%.
• At 20 years, the risk of cancer is about 23%.
• At 24 years, the risk of cancer is about 42%.

Patients with IBD also have a high chance of experiencing other disorders, including inflammation of the joints (arthritis), inflammation of the vertebrae (spondylitis), ulcers in the mouth and on the skin, the development of painful, red bumps on the skin, inflammation of several areas of the eye, and various disorders of the liver and gallbladder.