Defining and diagnosing irritable bowel syndrome

Approximately 20% of the general population has irritable bowel syndrome (IBS). Although the majority of these individuals do not consult a physician, IBS accounts for 25% of visits to a gastroenterologist and up to 12% of visits to a primary care physician. Consequently, the direct and indirect costs associated with IBS are estimated at $8 billion annually. IBS symptoms, with no apparent structural pathology, include altered bowel habits, abdominal pain/discomfort, and bloating. The Rome II criteria, a standardized guideline for the diagnosis of IBS, contains in its definition abdominal pain or discomfort associated with altered bowel habits. Bloating may often be present. Three patient subgroups are defined according to the predominant bowel symptom: constipation, diarrhea, or alternating constipation and diarrhea. Hematology, fecal occult blood test, flexible sigmoidoscopy, and lactose intolerance evaluations are recommended for all patients demonstrating symptoms of IBS. When indicated, tests are recommended to rule out bacterial or parasitic infections, pelvic floor muscle dyssynergia, colonic inertia, peptic ulcer, or inflammatory bowel disease.