What is an Irritable Bowel?
Medically, irritable bowel syndrome (IBS) is known by a variety of other terms: spastic colon, spastic colitis, mucous colitis and nervous or functional bowel. Usually, it is a disorder of the large intestine (colon), although other parts of the intestinal tract—even up to the stomach—can be affected. The colon, the last five feet of the intestine, serves two functions in the body. First, it dehydrates and stores the stool so that, normally, a well-formed soft stool occurs; second, it quietly propels the stool from the right side over to the rectum. This movement occurs by spontaneous, rhythmic contractions of the colon.
When IBS occurs, the colon does not contract normally. Instead, it contracts in a disorganized, sometimes violent, manner. The contractions may be terribly exaggerated and sustained, lasting for prolonged periods of time. One area of the colon may contract with no regard to another. At other times, there may be little bowel activity at all. These abnormal contractions result in changing bowel patterns with constipation being most common.
A second major feature of IBS is abdominal discomfort or pain. This may move around the abdomen rather than be localized in one area.
These disorganized, exaggerated and painful contractions lead to certain problems. The pattern of bowel movements is often altered. Diarrhea may occur, especially after meals, as the entire colon contracts and moves liquid stool quickly into the rectum. Or, localized areas of the colon may remain contracted for a prolonged time. When this occurs, which often happens in the section of colon just above the rectum, the stool may be retained there for a prolonged period and be squeezed into small pellets. Excessive water is removed from the stool and it becomes hard.
Also, air may accumulate behind these localized contractions, causing the bowel to swell. So bloating and abdominal distress may occur.
Some patients see gobs of mucous in the stool and become concerned. Mucous is a normal secretion of the bowel, although most of the time it cannot be seen. IBS patients sometimes produce large amounts of mucous, but this is not a serious problem.
Understanding this abnormal physiology should allow you to understand the causes of most IBS symptoms—constipation, diarrhea (intermittent), bloating and abdominal pain.
IBS Is Not A Disease
Although the symptoms of IBS may be severe, the disorder itself is not a serious one. There is no actual disease present in the colon. In fact, an operation performed on the abdomen would reveal a perfectly normal appearing large bowel.
Rather, it is a problem of abnormal function. The condition usually begins in young people, usually below 40 and often in the teens. The symptoms may wax and wane, being particularly severe at some times and absent at others. Over the years, the symptoms tend to become less intense.
IBS is extremely common and is present in perhaps half the patients that see a specialist in gastroenterology. It tends to run in families. The disorder does not lead to cancer. Prolonged contractions of the colon, however, may lead to diverticulosis, a disorder in which pockets balloon out from the bowel wall because of excessive, prolonged contractions.