The irritable bowel syndrome (IBS) is a chronic and sometimes disabling functional bowel disorder. Traditionally, this functional diagnostic label has been applied when no obvious structural or biochemical abnormalities are found, but emerging evidence suggests that distinct pathophysiological disturbances may account for the symptoms and that IBS is unlikely to be one disease or merely a psychiatric (somatosensory) disorder. The Rome IV criteria, derived from a consensus process by a multinational group of experts in functional gastrointestinal disorders, constitute the current standard for diagnosing IBS. According to these criteria, IBS is diagnosed on the basis of recurrent abdominal pain related to defecation or in association with a change in stool frequency or form. Bloating is a common accompanying symptom. Symptoms must be chronic, occurring at least once per week, on average, in the previous 3 months, with a duration of at least 6 months.
IBS negatively affects quality of life and work productivity. It has been estimated that patients would give up 10 to 15 years of life expectancy for an instant cure of the disease. The prevalence of IBS in the United States is between 7% and 16%, and the condition is most common in women and young people. Direct costs associated with IBS in the United States have been estimated, conservatively, at more than $1 billion. Thus, diagnosing IBS accurately, minimizing invasive investigations, and recommending effective treatment have an important role in efforts to reduce the societal and economic effects of the disease.