ABBR: IBS A syndrome marked by abdominal pain (often relieved by the passage of stool or gas); disturbances of evacuation (constipation, diarrhea, or alternating episodes of both); bloating and abdominal distention; and the passage of mucus in stools. These symptoms must be present despite the absence of anatomical, biochemical, or clinical evidence of active intestinal disease. It is not associated with weight loss, fevers, or intestinal bleeding.

INCIDENCE
The syndrome is common and found in as many as 15 to 25% of people in Western societies. Women are typically affected more often than men; in some studies the ratio of women to men is 3:1.

CAUSES
IBS occurs more often in patients who have had a history of physical or sexual abuse in childhood than in patients without such a history. Many studies have found a relationship between irritable bowel syndrome and a history of anxiety, psychological stress, or personality disorders. Physiologically, patients with IBS may have an increased or decreased rate of bowel motility.

SYMPTOMS AND SIGNS
Patients are symptomatic during the day, but they do not have pain, bloating, distention, diarrhea, or other abdominal symptoms while sleeping.

DIAGNOSIS
Young patients suspected of having IBS should undergo testing to exclude other illnesses. Tests should include a careful physical examination, complete blood count, metabolic panel, assessment of thyroid and liver functions; estimated sedimentation rate; and stool testing for occult blood. In constipation-predominant IBS, tests to evaluate colonic transit and rectal evacuation are useful. In diarrhea-predominant IBS, diagnostic testing should include assessments of carbohydrate or fat maldigestion. Patients over age 45 should also have sigmoidoscopy to rule out structural or anatomical lesions of the colon.

TREATMENT
Management of IBS should begin by establishing a therapeutic relationship between clinician and client. Educating the patient about the benign nature of the illness and the excellent long-term prognosis may be helpful. Avoiding poorly tolerated foods (trigger foods) may lessen symptoms. Foods that the patient has found to cause difficulties are eliminated (such as dairy products, beans, or some vegetables). Specific symptoms can be alleviated by taking bulk-forming agents (such as psyllium) by mouth, by increasing one's intake of fluids, and by engaging in increased levels of physical exercise. Low doses of antidepressant medications are sometimes helpful. Alternative therapy, including psychotherapy, hypnotherapy, imagery, and biofeedback, alone or in combination, may be effective in some patients.

IMPACT ON HEALTH
IBS is benign, the prognosis is good. However, in the U.S. alone, the evaluation and treatment of IBS currently accounts for more than 20 billion dollars in annual health care spending.

SYN: SEE: irritable colon; SEE: spastic colon