Irritable bowel syndrome (IBS) is a chronic, nonspecific disorder that affects up to 20% of the US population. Altered bowel habits may include constipation, diarrhea, straining at the stool, and feelings of incomplete evacuation. Many patients also experience fatigue, pelvic pain, somatic pain disorders, and sexual dysfunction as well as urologic or gynecologic complaints. Patients with IBS tend to experience more psychological and psychosocial disorders compared with non-IBS patients.
Presentation
IBS is a functional, biopsychosocial syndrome rather than an organic disease of the gastrointestinal (GI) tract. It presents mainly as altered bowel function with or without pain. If pain is present, it is poorly localized. Factors contributing to the spectrum of symptoms are psychosocial ones, alterations in bowel motility, and increased sensitivity to colonic sensation and visceral pain. To date, there is no specific symptom or objective radiographic/biochemical finding unique to irritable bowel syndrome (IBS).
The diagnosis is often one of exclusion based on patient symptoms and age at presentation. The symptom criteria commonly used are the Rome II criteria (TABLE 1). Patients typically present with either predominant diarrhea or constipation, but may have alternating episodes of both. Symptoms listed in the Rome criteria for IBS also occur with organic gastrointestinal disease; however, the occurrence of multiple symptoms increases the likelihood of a diagnosis of irritable bowel syndrome (IBS).
| Table 1. ROME II Criteria |
| Twelve weeks or more of the following in the previous 12 months (need not be consecutive) of abdominal pain or discomfort that has two of the three following features:
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Jennifer is a clinical pharmacologist. She helps doctors of all medical specialties choose medications. Jennifer consults about drug dosage, interactions, and side effects.