ABSTRACT
Functional gastrointestinal disorders (FGIDs) are common worldwide and cover a wide range of disorders attributable to the gastrointestinal tract that cannot be explained by structural or biochemical abnormalities. The diagnosis of these disorders relies on the symptom-based Rome criteria. In 2016 the Rome criteria were revised for infants/toddlers and for children and adolescents. In this review, we discuss the novel Rome IV criteria for infants and toddlers. The criteria for infant colic were drastically changed, whereas only minor changes were made for regurgitation, cyclic vomiting syndrome, functional diarrhea, infant dyschezia and functional constipation. In addition to this, the new Rome IV discusses underlying mechanisms of pain in infants and toddlers, including the neuro-development of nociceptive and pain pathways, the various factors that are involved in pain experience, and methods of pain assessment in infants and toddlers is essential for the clinician who encounters functional pain in this age group. Overall, the Rome IV criteria have become more distinctive for all disorders in order to improve the process of diagnosing pediatric FGIDs.