Irritable bowel syndrome (IBS), characterized by chronically recurring abdominal pain or discomfort and altered bowel habits, is one of the most common syndromes seen by gastroenterologists and primary-care providers, with a worldwide prevalence of 10% to 15%. In the absence of detectable organic causes, IBS is currently referred to as a functional or symptom-based syndrome, which is defined by symptom criteria (see the ROME criteria in
Table 21-1). IBS is one of several functional gastrointestinal (GI) disorders (including functional dyspepsia), and these other functional disorders are…