Ulcerative colitis is a chronic inflammatory disease of the large intestine (also known as the large bowel or colon). The most common symptoms are bloody diarrhea and abdominal pain Figure 01. Ulcerative colitis involves periodic inflammation and loss of tissue (ulceration) of the lining of the large intestine. The condition produces frequent bouts of urgent, bloody diarrhea, and sometimes with abdominal cramping. It usually begins in childhood or early adulthood, and is characterized by periods of exacerbations and remissions. During remissions, the person may feel well and be free of symptoms.
Ulcerative colitis shares many common characteristics with Crohn’s disease, another inflammatory bowel disease. About 15% of patients with inflammatory bowel disease have features of both conditions, and cannot be clearly diagnosed with one or the other.
Figure 01. Anatomy of the digestive system
The more the bowel is inflamed, the more severe the disease. The inflammation and ulceration of ulcerative colitis is present in the rectum, and may spread up through the large intestine in a characteristically continuous manner. Disease severity depends in part on how much of the intestine is affected. If disease is confined to the rectum (proctitis), symptoms are often relatively minor. Proctosigmoiditis is the term used when both the rectum and sigmoid colon are involved. Those who have disease in the entire colon (pancolitis) usually have the most severe symptoms.
Colitis can be a serious disease requiring hospitalization, surgical removal of the colon, and an increased risk of colon cancer. Because colitis usually begins in young adulthood, it can disrupt a person’s education, career goals, and social life. Although it is not considered to be a fatal disease, it can cause serious anemia, malnutrition, and disability during prolonged attacks, and sometimes requires hospitalization. Although effective medicines can help most people keep the disease in check, for some, the colon must eventually be removed for relief.
Two of the most dangerous complications of ulcerative colitis are holes (perforations) in the intestine and a condition known as toxic megacolon, in which the colon becomes expanded (distended) and is in immediate danger of perforation. Both perforation and toxic megacolon are medical emergencies that must be treated at once, usually by removal of part or the entire colon.
Ulcerative colitis also brings the long-term risk of colon cancer. Patients are advised to undergo periodic screening with colonoscopy on a schedule determined by the extent and duration of their disease. During a colonoscopy the doctor inserts a long and flexible lighted tube, an endoscope, into the anus to see if there is inflammation, bleeding, or ulcers on the colon wall. In screening for cancer and pre-cancerous changes, the doctor will do a number of biopsies—that is, take samples of tissue from the lining of the colon to examine under a microscope. Some people opt to have their colon removed to prevent cancer from developing.
A small percentage of patients with ulcerative colitis also have inflammation in other parts of their body. Less than 5% of patients with ulcerative colitis also have primary sclerosing cholangitis, an inflammatory disease of the biliary tract that delivers bile (a digestive fluid) from the liver to the intestines. The skin, joints, and eyes are also sometimes affected.
The precise reason some people develop ulcerative colitis is not understood. Colitis results from an abnormal immune response, perhaps to substances in food. Ulcerative colitis has been blamed on genetic factors, bacteria, viruses, stress, and diet, but no theory offers a clear-cut explanation of the disease. It tends to run in families, and is more common in certain ethnic groups, indicating that genetics are at least partially responsible.
Whatever the reason, the body mounts an inflammatory response in the colon as if a foreign invader, such as a bacterium, a virus, or an allergen, were present. The abnormal response may continue even after the provoking agent is no longer present.
People with ulcerative colitis may be considerably emotionally distressed, leading some to suspect that stress is a primary cause of the disease. There is no evidence, however, that psychological factors cause the disease. Instead, most experts believe that emotional stress is an understandable and common response to a problem that frequently recurs beyond one’s control.
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