Bowel Disorders.

Bowel disorders (BDs), previously termed functional bowel disorders, are highly prevalent disorders worldwide. These disorders affect individuals across all demographic and socioeconomic groups and have substantial economic consequences, in addition to significantly reducing quality of life. Since the Rome IV publication in 2016, research in the basic and clinical sciences has provided new insights in epidemiology, etiology, pathophysiology, diagnosis, and treatment of BDs, creating the need to revise the diagnostic framework of BDs. This article presents the updated Rome V classification of BDs in 6 distinct categories: irritable bowel syndrome, chronic constipation, functional diarrhea, functional abdominal bloating, unclassified BD, and opioid-induced constipation. Each disorder is defined, followed by sections on epidemiology, rationale for changes from prior criteria, clinical evaluation, pathophysiology, and treatment. It is in hope that the Rome V BD Committee will assist clinicians and researchers in improving diagnosis, patient care, and scientific endeavors of these common and burdensome disorders.