The Medical Minute: Recognizing irritable bowel syndrome

April 18, 2007

by Ann Ouyang
April is irritable bowel syndrome (IBS) awareness month. IBS affects about 10 to 20 percent of the general population to varying degrees. It is one of the most common gastrointestinal disorders leading patients to seek medical care.

IBS is one of the functional bowel disorders, a group of conditions in which symptoms arise from a disorder in the normal highly integrated function of the intestine in the absence of an underlying structural or inflammatory condition.

Patients with IBS may suffer from abdominal pain and altered bowel habits that prevent them from arranging any family outing and that limits them to places that have easily accessible bathrooms, and yet have no abnormal labwork or imaging studies.

In an age where medical mysteries are solved daily on television through the latest, most sophisticated tests, it is difficult for patients to accept or understand that symptoms that may severely impair their quality of life cannot be diagnosed by testing.

How can patients have such severe symptoms without any lab or diagnostic tests being abnormal? An understanding of the normal bowel function is needed to appreciate how abnormal function may result in symptoms.

The intestinal tract, from esophagus to rectum, is a long muscular tube with a specialized lining that can secrete enzymes and fluids for digesting food and allow absorption of digested food and fluids for nutrition and fluid balance.

The muscle layers of the different parts of the intestine move food along in an organized and coordinated way so that these enzymes and fluids secreted by the lining can effectively digest food and allow nutrients to be absorbed. Most of this highly organized activity occurs with no awareness of these events.

If there is some altered movement or motility, such as occurs with viral gastroenteritis, the altered function of the gut is experienced as cramping or pain and change in bowel habits.

In patients with IBS, the well-integrated function of the bowel may be disrupted and cause symptoms more frequently. Food is the major stimulus for the intestine to start contracting, and in patients with IBS, there may be an exaggerated response to food, resulting in pain and altered bowel habits following meals.

Other factors that can alter the normal function of the intestine are previous bowel infections or inflammation and stress. The well-known phrase "gut-wrenching experience" underscores the widely recognized fact that stress can alter the function of the bowels.

Patients with functional bowel disorders such as IBS suffer from a chronic condition with symptoms which people tend to keep private. This, along with the fact that test results are normal, can result in a sense of isolation and fear that some life-threatening condition exists which doctors have not been able to diagnose. Patients sometimes worry that if there are no abnormal test results, physicians and family will not believe the severity of the symptoms.

Diagnosing IBS and determining the potential aggravating factors in an individual patient requires a careful history and physical examination and some selected studies to exclude other possible diagnoses. The good news is that this condition does not result in any permanent damage to the intestine and does not increase the risk of cancer. In most patients, individualized changes in diet, lifestyle and medications can result in control of symptoms.

More information on IBS is available at http://digestive.niddk.nih.gov/ddiseases/pubs/ibs/ online.

Ann Ouyang is a professor of medicine and staff physician in the Division of Gastroenterology and Hepatology at Penn State College of Medicine and Penn State Milton S. Hershey Medical Center.

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Last Updated March 19, 2009