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Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders that physicians treat. Patients with this non life-threatening condition may present with a broad range of symptoms which typically include abdominal pain associated with altered bowel habits, including constipation, diarrhea, or alternating constipation and diarrhea, and a less common presentation of painless diarrhea. Although the symptoms are typically intermittent, they may be continuous and should be present for at least three months before the diagnosis of irritable bowel syndrome is considered.
In the late 1970's, Manning and colleagues identified several characteristic symptoms of IBS. These symptoms include; abdominal distention, abdominal pain relief following a bowel movement, increased frequency of stools, changes in the consistency of the stools, passage of mucus, and the sensation of incomplete evacuation.(1) Evaluative and diagnostic criteria that include the "Manning Criteria" have been developed and used in clinical practice.(2) Patients with irritable bowel syndrome are also more likely to have other symptoms such as gastro esophageal reflux with heartburn, dysphagia, noncardiac chest pain, urologic dysfunction, fatigue, and gynecologic problems.(3) In general a patient's likelihood of having IBS increases as they present with more symptoms included within the "Manning Criteria" and other possible causes of the symptoms can be eliminated. Other conditions that may present with symptoms similar to IBS include; lactose intolerance, giardiasis, Crohn's disease, ulcerative colitis, neoplasms, obstructions, ischemic conditions, certain psychiatric disorders and endometriosis.
Irritable bowel syndrome is considered a "functional" disorder because the problems persist without an identifiable etiology in what appears to be a normal intestinal tract. IBS is likely the culmination of several coexisting disorders with no consistent findings among any subgroup of patients. Irritable bowel syndrome is often assumed to be caused by altered colonic motility or sensation. Periods of acute stress, such as eating or anger, may lead to IBS exacerbations for some patients, but there is no proof that chronic emotional stress is the cause of IBS.(2) Evidence suggests that gut innervation may mediate the pathophysiology of IBS.(3)
Psychosocial factors are an important part of fully understanding of irritable bowel syndrome, playing a vital role in the development, precipitation and perpetuation of IBS. Though less than half of IBS patients seek medical attention, there is an increased frequency of psychiatric diagnoses among those who do. Improvement in the clinical outcome does occur when psychosocial factors are addressed in the assessment and management of IBS patients.(4) Psychosocial factors do not cause IBS symptoms, they do influence the patients response to IBS. The presence of psychosocial disorder is an indicator for the likelihood that the patient will seek medical attention for IBS as well as other medical conditions.(3)
The diagnosis of IBS is made more upon the basis of exclusion than that of pertinent medical findings. The findings from the physical exam are generally unremarkable. Routine laboratory test results are typically normal in IBS. Yet both are essential diagnostic tools in an effort to eliminate other potential problems. Flexible sigmoidoscopy is performed in certain patient populations to exclude neoplasms and inflammatory bowel disease. An extensive history is an excellent way to assess IBS. The history should involve an assessment abdominal pain, bowel habits, the "Manning Criteria," medication usage and an extensive diet history. The diet history should focus on foods sweetened with fructose or sorbitol, and the exclusion of lactose intolerance. It is also important to consider addressing any
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