This is the first attempt at defining criteria for functional gastrointestinal disorders (FGIDs) in infancy, childhood, and adolescence. The decision-making process was as for adults and consisted of arriving at consensus, based on clinical experience. This paper is intended to be a quick reference. The classification system selected differs from the one used in the adult population in that it is organized according to main complaints instead of being organ-targeted. Because the child is still developing, some disorders such as toddler's diarrhea (or functional diarrhea) are linked to certain physiologic stages; others may result from behavioral responses to sphincter function acquisition such as fecal retention; others will only be recognizable after the child is cognitively mature enough to report the symptoms (e.g., dyspepsia). Infant regurgitation, rumination, and cyclic vomiting constitute the vomiting disorders. Abdominal pain disorders are classified as: functional dyspepsia, irritable bowel syndrome (IBS), functional abdominal pain, abdominal migraine, and aerophagia. Disorders of defecation include: infant dyschezia, functional constipation, functional fecal retention, and functional non-retentive fecal soiling. Some disorders, such as IBS and dyspepsia and functional abdominal pain, are exact replications of the adult criteria because there are enough data to confirm that they represent specific and similar disorders in pediatrics. Other disorders not included in the pediatric classification, such as functional biliary disorders, do occur in children; however, existing data are insufficient to warrant including them at the present time. For these disorders, it is suggested that, for the time being, clinicians refer to the criteria established for the adult population.

In this report the functional anorectal disorders, the etiology of which is currently unknown or related to the abnormal functioning of normally innervated and structurally intact muscles, are discussed. These disorders include functional fecal incontinence, functional anorectal pain, including levator ani syndrome and proctalgia fugax, and pelvic floor dyssynergia. The epidemiology of each disorder is defined and discussed, their pathophysiology is summarized and diagnostic approaches and treatment are suggested. Some suggestions for the direction of future research on these disorders are also given.

The term "dysfunction" defines the motor disorders of the gall bladder and the sphincter of Oddi (SO) without note of the potential etiologic factors for the difficulty to differentiate purely functional alterations from subtle structural changes. Dysfunction of the gall bladder and/or SO produces similar patterns of biliopancreatic pain and SO dysfunction may occur in the presence of the gall bladder. The symptom-based diagnostic criteria of gall bladder and SO dysfunction are episodes of severe steady pain located in the epigastrium and right upper abdominal quadrant which last at least 30 minutes. Gall bladder and SO dysfunctions can cause significant clinical symptoms but do not explain many instances of biliopancreatic type of pain. The syndrome of functional abdominal pain should be differentiated from gall bladder and SO dysfunction. In the diagnostic workup, invasive investigations should be performed only in the presence of compelling clinical evidence and after non-invasive testing has yielded negative findings. Gall bladder dysfunction is suspected when laboratory, ultrasonographic, and microscopic bile examination have excluded the presence of gallstones and other structural abnormalities. The finding of decreased gall bladder emptying at cholecystokinin-cholescintigraphy is the only objective characteristic of gall bladder dysfunction. Symptomatic manifestation of SO dysfunction may be accompanied by features of biliary obstruction (biliary-type SO dysfunction) or significant elevation of pancreatic enzymes and pancreatitis (pancreatic-type SO dysfunction). Biliary-type SO dysfunction occurs more frequently in postcholecystectomy patients who are categorized into three types. Types I and II, but not type III, have biochemical and cholangiographic features of biliary obstruction. Pancreatic-type SO dysfunction is less well classified into types. When non-invasive investigations and endoscopic retrograde cholangiopanreatography show no structural abnormality, manometry of both biliary and pancreatic sphincter may be considered.

The Rome diagnostic criteria for the functional bowel disorders and functional abdominal pain are used widely in research and practice. A committee consensus approach, including criticism from multinational expert reviewers, was used to revise the diagnostic criteria and update diagnosis and treatment recommendations, based on research results. The terminology was clarified and the diagnostic criteria and management recommendations were revised. A functional bowel disorder (FBD) is diagnosed by characteristic symptoms for at least 12 weeks during the preceding 12 months in the absence of a structural or biochemical explanation. The irritable bowel syndrome, functional abdominal bloating, functional constipation, and functional diarrhea are distinguished by symptom-based diagnostic criteria. Unspecified FBD lacks criteria for the other FBDs. Diagnostic testing is individualized, depending on patient age, primary symptom characteristics, and other clinical and laboratory features. Functional abdominal pain (FAP) is defined as either the FAP syndrome, which requires at least six months of pain with poor relation to gut function and loss of daily activities, or unspecified FAP, which lacks criteria for the FAP syndrome. An organic cause for the pain must be excluded, but aspects of the patient's pain behavior are of primary importance. Treatment of the FBDs relies upon confident diagnosis, explanation, and reassurance. Diet alteration, drug treatment, and psychotherapy may be beneficial, depending on the symptoms and psychological features.

While widely used in research, the 1991 Rome criteria for the gastroduodenal disorders, especially symptom subgroups in dyspepsia, remain contentious. After a comprehensive literature search, a consensus-based approach was applied, supplemented by input from international experts who reviewed the report. Three functional gastroduodenal disorders are defined. Functional dyspepsia is persistent or recurrent pain or discomfort centered in the upper abdomen; evidence of organic disease likely to explain the symptoms is absent, including at upper endoscopy. Discomfort refers to a subjective, negative feeling that may be characterized by or associated with a number of non-painful symptoms including upper abdominal fullness, early satiety, bloating, or nausea. A dyspepsia subgroup classification is proposed for research purposes, based on the predominant (most bothersome) symptom: (a) ulcer-like dyspepsia when pain (from mild to severe) is the predominant symptom, and (b) dysmotility-like dyspepsia when discomfort (not pain) is the predominant symptom. This classification is supported by recent evidence suggesting that predominant symptoms, but not symptom clusters, identify subgroups with distinct underlying pathophysiological disturbances and responses to treatment. Aerophagia is an unusual complaint characterized by air swallowing that is objectively observed and troublesome repetitive belching. Functional vomiting refers to frequent episodes of recurrent vomiting that is not self-induced nor medication induced, and occurs in the absence of eating disorders, major psychiatric diseases, abnormalities in the gut or central nervous system, or metabolic diseases that can explain the symptom. The current classification requires careful validation but the criteria should be of value in future research.

The functional esophageal disorders include globus, rumination syndrome, and symptoms that typify esophageal diseases (chest pain, heartburn, and dysphagia). Factors responsible for symptom production are poorly understood. The criteria for diagnosis rest not only on compatible symptoms but also on exclusion of structural and metabolic disorders that might mimic the functional disorders. Additionally, a functional diagnosis is precluded by the presence of a pathology-based motor disorder or pathological reflux, defined by evidence of reflux esophagitis or abnormal acid exposure time during ambulatory esophageal pH monitoring. Management is largely empirical, although efficacy of psychopharmacological agents and psychological or behavioral approaches has been established for several of the functional esophageal disorders. As gastroesophageal reflux disease overlaps in presentation with most of these disorders and because symptoms are at least partially provoked by acid reflux events in many patients, antireflux therapy also plays an important role both in diagnosis and management. Further understanding of the fundamental mechanisms responsible for symptoms is a priority for future research efforts, as is the consideration of treatment outcome in a broader sense than reduction in esophageal symptoms alone. Likewise, the value of inclusive rather than restrictive diagnostic criteria that encompass other gastrointestinal and non-gastrointestinal symptoms should be examined to improve the accuracy of symptom-based criteria and reduce the dependence on objective testing.

The functional gastrointestinal disorders (FGID) are the most frequent conditions seen in gastroenterology practice and comprise a major portion of primary care. Psychosocial factors are important in these disorders with regard to: (1) their effects on gut physiology; (2) their modulation of the symptom experience; (3) their influence on illness behavior; (4) their impact on outcome; and (5) the choice of the therapeutic approach. This paper provides a review and consensus of the existing literature by gastroenterologists, psychiatrists, psychologists, physiologists, and health services investigators. Evidence is provided to support the biopsychosocial model as a basis for understanding and treating these disorders, and epidemiological and clinical information on the relations of psychosocial factors to gut physiology, symptom presentation, health behavior, and outcome is offered. Features of motility, personality, abuse history, health concerns, and treatment-seeking differ between patients with FGID and healthy controls, but they are not specific to FGID. They occur in other patients with chronic medical conditions and/or psychiatric disorders. Review of treatment trials indicates clear support for psychotherapeutic treatments, especially in the long term, as well as some evidence for the benefit of antidepressants in FGID, even in the absence of improvements in mood.

Many of the symptoms characteristic of the functional gastrointestinal disorders (FGID) are consistent with dysfunction of the motor and/or sensory apparatus of the digestive tract. Those aspects of sensorimotor dysfunction most relevant to the FGID include alterations in: gut contractile activity; myoelectrical activity; tone and compliance; and transit, as well as an enhanced sensitivity to distension, in each region of the gastrointestinal tract. Assessment of these phenomena involves a number of techniques, some well established and others requiring further validation. Using such techniques, researchers have reported a wide range of alterations in sensory and in motor function in the FGID. Importantly, however, relationships between such dysfunction and symptoms have been relatively weak, and so the clinical relevance of the former remains unclear. Moreover, the proportions of patients in the various symptom subgroups who display dysfunction, and the extent and severity of their symptoms, require better characterization. On a positive note, progress is occurring on several fronts, especially in relation to functional dyspepsia and irritable bowel syndrome, and based on the data gathered to date, a number of areas where further advances are required can be highlighted.