Irritable bowel syndrome
Irritable bowel syndrome (IBS) is a common intestinal condition characterizedby abdominal pain and cramps; changes in bowel movements (diarrhea, constipation, or both); gassiness; bloating; nausea; and other symptoms. There is no cure for IBS. Much about the condition remains unknown or poorly understood; however, dietary changes, drugs, and psychological treatment are often able to eliminate or substantially cureduce its symptoms.
IBS was once called--among other things--colitis, spastic colon, nervous colon, and spastic bowel. Some of these names reflected the now outdated belief that IBS is a purely psychological disorder, a product of the patient's imagination. Although modern medicine recognizes that stress can trigger IBSattacks, medical specialists agree that IBS is a genuine physical disorder--or group of disorders--with specific identifiable characteristics.
The symptoms of IBS tend to rise and fall in intensity rather than growing steadily worse over time. They always include abdominal pain, which may be relieved by defecation; diarrhea or constipation; or diarrhea alternating with constipation. Other symptoms--which vary from person to person--include cramps;gassiness; bloating; nausea; a powerful and uncontrollable urge to defecate(urgency); passage of a sticky fluid (mucus) during bowel movements; or the feeling after finishing a bowel movement that the bowels are still not completely empty. The accepted diagnostic criteria--known as the Rome criteria--require at least three months of continuous or recurrent symptoms before IBS canbe confirmed.
Researchers remain unsure about the cause or causes of IBS. It is called a functional disorder because it is thought to result from changes in the activity of the major part of the large intestine (the colon). After food is digested by the stomach and small intestine, the undigested material passes in liquid form into the colon, which absorbs water and salts. This process may take several days. In a healthy person the colon is quiet during most of that period except after meals, when its muscles contract in a series of wavelike movements called peristalsis. Peristalsis helps absorption by bringing the undigested material into contact with the colon wall. It also pushes undigested material that has been converted into solid or semisolid feces toward the rectum,where it remains until defecation. In IBS, however, the normal rhythm and intensity of peristalsis is disrupted. Sometimes there is too little peristalsis, which can slow the passage of undigested material through the colon and cause constipation. Sometimes there is too much, which has the opposite effectand causes diarrhea.
Some kinds of food and drink appear to play a key role in triggering IBS attacks. Food and drink that healthy people can ingest without any trouble may disrupt peristalsis in IBS patients, which probably explains why IBS attacks often occur shortly after meals. Chocolate, milk products, caffeine (incoffee, tea, colas, and other drinks), and large quantities of alcohol are some of the chief culprits. Other kinds of food have also been identified as problems, however, and the pattern of what can and cannot be tolerated is different for each person. Characteristically, IBS symptoms rarely occur at nightand disrupt the patient's sleep.
Stress is an important factor in IBS because of the close nervous system connections between the brain and the intestines. Although researchers do not yetunderstand all of the links between changes in the nervous system and IBS, they point out the similarities between mild digestive upsets and IBS. Just ashealthy people can feel nauseated or have an upset stomach when under stress, people with IBS react the same way, but to a greater degree. Finally, IBS symptoms sometimes intensify during menstruation, which suggests that female reproductive hormones are another trigger.
Diagnosing IBS is a fairly complex task because the disorder does not producechanges that can be identified during a physical examination or by laboratory tests. When IBS is suspected, the doctor (who can be either a family doctoror a specialist) needs to determine whether the patient's symptoms satisfy the Rome criteria. The doctor must rule out other conditions that resemble IBSby questioning the patient about his or her physical and mental health (themedical history), performing a physical examination, and ordering laboratory tests.
Dietary changes, sometimes supplemented by drugs or psychotherapy, are considered the key to successful treatment. A low-fat, high-fiber diet free of problem-causing substances such as lactose, caffeine, beans, cabbage, cucumbers,broccoli, fatty foods, alcohol, and medications should be followed. Bran or 15-25 grams a day of an over-the-counter psyllium laxative (Metamucil or Fiberall) may also help both constipation and diarrhea. The patient can still havemilk or milk products if lactose intolerance is not a problem. People with irregular bowel habits--particularly constipated patients--may be helped by establishing set times for meals and bathroom visits.
Although a high-fiber diet remains the standard treatment for constipated patients, laxatives may be prescribed. Loperamide (Imodium) and cholestyramine (Questran) are suggested for diarrhea. Abdominal pain after meals can be reduced by taking antispasmodic drugs such as hyoscyamine (Anaspaz,Cystospaz, or Levsin) or dicyclomine (Bemote, Bentyl, or Di-Spaz) before eating.
Psychological counseling or behavioral therapy may be suggested for some patients to reduce anxiety and to learn to cope with the pain and other symptomsof IBS.
IBS is not a life-threatening condition. It does not cause intestinal bleeding or inflammation, nor does it cause other bowel diseases or cancer. Although IBS can last a lifetime, in up to 30% of cases the symptoms eventually disappear. Even if the symptoms cannot be eliminated, with appropriate treatment they can usually be brought under control to the point where IBS becomes merely an occasional inconvenience. Treatment requires a long-term commitment, however; six months or more may be needed before the patient notices substantial improvement.