Irritable bowel syndrome (IBS) is an extremely common functional gastrointestinal disorder that affects 10-20% of the general population and accounts for a significant amount of primary care and gastroenterology visits. IBS occurs most often in the third and fourth decades of life and women are two to four more times likely than men to be diagnosed with IBS. The underlying cause of IBS remains to be elucidated, although many possibilities have been proposed. These possible etiologies include hormonal influences, food intolerance or allergy, a post-infectious phenomenon, bacterial growth in the gut, increased sensitivity to pain perception, and a dysfunctional connection between the brain and the gut.
People with IBS experience a wide array of symptoms, with the predominant symptom being chronic or recurrent abdominal pain associated with altered bowel habits. Typically the pain comes intermittently and last 2-4 days at a time. Other symptoms that are common in IBS include improvement in pain with defecation (having a bowel movement), bloating, abnormal stool frequency (less than 3 bowel movement per week or over 3 bowel movement per day), abnormal stool form (hard or watery), straining with defecation, urgency with defecation (sudden need to defecate), a feeling of incomplete evacuation with defecation, and passing of mucus with defecation. These symptoms need not all be present to reach a diagnosis of IBS. A diagnosis of IBS is usually made when people fulfill certain symptom-based diagnostic criteria (“Rome III criteria”) after evaluation by a physician is performed to exclude other possible diseases. The extent of evaluation should be determined on an individual basis by the treating physician. There is no evidence that IBS leads to more serious gastrointestinal diseases. A variety of non-GI related symptoms have been found to be more common in patients with IBS, including headache, fatigue, and back pain. IBS has also been found to be associated with depression or anxiety in up to 50% of people. Symptoms that are not usually compatible with IBS and should warrant further and more immediate evaluation include but are not limited to: onset of symptoms when a person is over fifty years-old, unintentional weight loss, night-time symptoms, a family history of GI cancers, rectal bleeding, anemia (low blood level), being male, an abnormal physical exam, a short history of symptoms, fever or chills, recent antibiotic use, or severe, unrelenting diarrhea.
