Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGIDs) comprise a group of conditions that relate to the gastrointestinal (GI) tract. These disorders cannot be completely explained by anatomical or biochemical abnormalities (infectious, inflammatory). FGIDs commonly afflict children across a broad range of manifestations and are defined primarily by symptoms. The symptom-based criteria employed to classify FGIDs have been developed by expert consensus and opinion under the auspices of the Rome Foundation, and are referred to as Rome IV Criteria. FGIDs pose diagnostic challenges as there is no anatomical or laboratory-based testing that is used to define them. FGID defining criteria strive not to be entirely based on diagnoses of exclusion, but rather aim to be based on objective, unambiguous, and accurate criteria derived from the presentation as elicited during obtaining the medical history and performing a clinical examination. These criteria strive to be uniform, reliable, reproducible, and to minimize unnecessary evaluations/testing with low diagnostic yield or relevance. FGIDs often coexist across the spectrum of GI disorders, such as inflammatory bowel disease, celiac disease, or irritable bowel syndrome (IBS). FGIDs may be influenced by psychosocial stressors, or a result of an otherwise benign episode of abdominal pain. The brain–gut axis likely plays a prominent role in the pathophysiology of many FGIDs. Some FGID manifestations may relate to dysbiosis and the intestinal microbiota. There may be a genetic basis to some of these disorders as well. Early life physical or psychologic stressors may manifest later as FGID. Maladaptive responses or lack of adequate coping skills may complicate the treatment of FGIDs but may also allow for a valuable approach to management using behavioral therapies.

FGIDs encompass 2 age groups: infants and toddlers or children and adolescents. Aerophagia, functional constipation, and cyclical vomiting span both age groups ( Fig. 368.1 ).

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Age distribution of functional gastrointestinal disorders in infants, toddlers, children, and adolescents. *History may not be reliable below this age. FAP-NOS , Functional abdominal pain—not otherwise specified.

(Modified from Benninga MA, Nurko S, Faure C, et al: Childhood functional gastrointestinal disorders: neonate/toddler, Gastroenterology 150[6]:1443–1455.e2, 2016.)

Infant regurgitation implies effortless retrograde and involuntary passage of gastric contents from the stomach cephalad and is more commonly referred to as gastroesophageal reflux ( Table 368.1 ). When refluxate reaches the oropharynx and is visible, it is labelled as regurgitation. This phenomenon is normal for healthy infants, unless there are complications associated with the process, such as esophageal inflammation, dysphagia, feeding difficulties, inadequate oral intake to meet needs leading to failure to thrive, or the inability to protect the airway with risk for aspiration; in this setting gastroesophageal reflux disease is the correct designation ( Chapter 349 ). Unlike vomiting, regurgitation does not include the forceful expulsion of gastric contents via the mouth. Rumination is a different phenomenon, in that previously ingested and swallowed food is brought back up to the oral cavity, remasticated and subsequently reswallowed.

Infant rumination is defined as a habitual regurgitation of gastric contents into the oropharynx to allow for remastication and reswallowing ( Table 368.2 ). It is thought to be a form of self-stimulation and may occur in the setting of emotional or sensory deprivation. The regurgitation of gastric contents is effortless and can be remasticated and reswallowed versus expulsion from the oropharynx. Infant rumination occurs between 3 and 8 mo of age and does not respond to measures used to manage regurgitation. This phenomenon does not occur during socialization/interaction with individuals, does not occur during sleep, and is not associated with distress. Empathy and nurturing lay the foundation for management. Behavior management is important to achieve resolution of this phenomenon.

Infant colic ( Chapter 22.1 ) is a normal developmental process associated with fussiness, irritability, and difficultly consoling the infant ( Table 368.3 ). A trigger is not identifiable. This phenomenon usually occurs between 1 and 4 mo of age. The typical behavior usually leads to consultation with a pediatrician or a pediatric gastroenterologist out of suspicion for abdominal pain. Patients are often unnecessarily treated for gastroesophageal reflux, gas, or suspected cow-milk protein or soy allergy leading to dietary changes and the use of medications for the management of acidity or gas. Probiotics have been investigated as a possible treatment. Probiotics may be more beneficial for breast versus cow-milk-fed infants. Soothing in a quiet, tranquil space may also be effective. Providing reassurance, education, support, and ensuring adequate coping skills and support for family members are key. This is a self-limited phenomenon that resolves on its own.

Functional diarrhea is often also referred to as toddler's diarrhea ( Table 368.4 ). This condition excludes steatorrhea. Excessive fruit juice with nonabsorbable carbohydrates (i.e., sorbitol) intake coupled with a low-fat diet drive this osmotic process. An evaluation of the diet for possible other etiologies as well as assessment for infections, inflammation, antibiotic, and laxative use is important. In addition, assessments of growth as well as ruling out fecal impaction and encopresis via digital rectal examination are important. The diarrhea is usually stool colored, painless, liquid-watery, and may contain undigested foods. Growth is usually not affected. Dietary changes such as reducing fruit juice intake as well as fructose are helpful in resolving symptoms.

Infant dyschezia is manifested by infants straining prior to defecation associated with visible distress, crying, a red/purple facial discoloration, with symptoms persisting for 10-20 min alleviated by the passage in stools, limited to infants < 9 mo of age. There is no associated obstruction or anal anomaly; stools are passed several times daily and are not associated with other health problems. Dyschezia is thought to represent discoordinated intraabdominal musculature contraction with pelvic floor relaxation. A good medical history and neurological and digital rectal examinations to rule out anatomical or neuromuscular abnormalities are key. Normal growth is to be expected. Reassurance provides the basis of management. Laxative, suppository, or digital manipulation is not required and may be counterproductive.

Functional constipation ( Chapter 358.3 ) is associated with withholding behaviors, which in turn may relate to social stressors or changes in social situations ( Table 368.5 ). These often occur at the time of diet changes in infants and at the initiation of toilet training for toddlers. Painful passage of hard, large caliber stools < 2 times/wk in the setting of withholding behaviors is noted. For those children who have previously been toilet trained, fecal incontinence or encopresis is often observed. Large-caliber stools that obstruct the toilet are also noted frequently. Abdominal examination may reveal a palpable mass, and digital rectal examination may reveal a large rectal stool mass. The differential diagnosis for constipation is extensive, with functional constipation and slow transit constipation common. Dietary factors may play a role. Anorectal malformations, neuromuscular and motility issues may also present as such. Hirschsprung disease is on the differential diagnosis. The evaluation and management are based on a detailed history and thorough physical examination. A defecation history extending to the first 1-2 days of life is particularly important, as almost all children pass their first bowel movement within the first 48 hr of life. Assessment for associated signs and symptoms and growth trends are important. Red flags are noted in Table 368.6 . Imaging plays a role, and rectal suction biopsy or even full thickness rectal biopsy may be required to rule out Hirschsprung disease in cases with high index of suspicion. Management encompasses dietary and lifestyle changes, and medications to soften stool with osmotic laxatives over stimulant laxatives. The goal is to achieve painless defection and resolve fear and withholding revolving around defecation. Behavior modification including reassurance and positive incentive reward systems are useful. Avoidance of toilet training until symptoms resolve and the child shows interest or willingness to proceed are generally advocated.