Review of Pathophysiology and Diagnosis of Irritable Bowel Syndrome

Irritable bowel syndrome is one of the most common functional gastrointestinal disorders with the prevalence of 10-20% of the world’s population. This syndrome usually manifests as abdominal pain or discomfort associated with altered bowel habits, and it is usually diagnosed based on patient’s history and there is no specific diagnostic test for it. However, it should be noted that definitive diagnosis is made after ruling out other organic diseases. The most common clinical manifestations are abdominal pain or discomfort, constipation, diarra or alternating constipation and diarrhea, and abdominal bloating. Various mechanisms have been described for pathogenesis of this disorder, including motor dysfunction, visceral hypersensitivity, mild inflammation, and stress. Genetic factors seem to be involved in inflammation and regional immune responses and subsequently, susceptibility to IBS. But it seems that several factors are involved in the presentation of IBS symptoms. Although most patients do not refer for medical care, the disease imposes a considerable cost on patient and healthcare system and considerably overshadows the subject’s quality of life. Having knowledge about the precise pathophysiology and diagnostic criteria are necessary for better identification of patients and choosing a more appropriate treatment approach.