Functional dyspepsia is defined as persistent or recurrent abdominal pain localized to the upper abdomen occurring once per week for at least 2 months. As in all functional disorders there is no inflammatory, anatomic, metabolic, or neoplastic process that explains the child’s symptoms. Epigastric or midabdominal discomfort or burning occurs in the absence of associated gastrointestinal inflammation, gastroesophageal reflux, or structural abnormalities. Other dyspeptic symptoms may include nausea, bloating, regurgitation, heartburn, belching, anorexia, early satiety, and upper abdominal fullness. These symptoms may be similar to those reported by patients with acid peptic disease, lactose intolerance, and gallbladder or pancreatic disease. Patients with functional dyspepsia also may have an irritable bowel component to their pain, with lower abdominal cramping and alteration in stool frequency or consistency. The evaluation of these patients can include a complete blood cell count, comprehensive metabolic profile, determination of the sedimentation rate, measurement of amylase and lipase levels, and stool examination for ova and parasites. In selected cases, an abdominal ultrasonography, upper gastrointestinal series with small bowel followthrough, or upper gastrointestinal endoscopy with biopsy should be performed to exclude anatomic abnormalities and evaluate for the presence of significant mucosal inflammation or infection. The controversy regarding the significance of Helicobacter pylori infection and its treatment in patients with dyspepsia is ongoing. As for all patients with functional abdominal pain, education and reassurance are the most important components of treatment. Avoidance of aggravating foods and medications such as nonsteroidal anti-inflammatory medications is recommended. In patients with functional dyspepsia, stress reduction and an empiric trial of a histamine₂ (H₂) receptor antagonists or proton pump inhibitors may decrease symptoms.

Individuals with irritable bowel syndrome experience pain that occurs at least once a week for at least 2 months. Pain is typically described as cramping in nature and is associated with an altered stool pattern. Patients with irritable bowel syndrome report at least two of the following three symptoms:

Irritable bowel syndrome afflicts 10% to 20% of adolescents and adults. Patients with irritable bowel syndrome typically experience abdominal pain in the periumbilical region or lower abdomen. Patients can have diarrhea, constipation, or both. Patients may also have such symptoms as fecal urgency, straining during a bowel movement, a sensation of incomplete stool evacuation, relief from pain with the passage of stools, the passage of mucus, and increased flatulence or bloating. The symptoms of irritable bowel syndrome may be similar to those described by patients with inflammatory bowel disease, parasitic infections, or lactose intolerance, all of which should be considered in the evaluation. Screening should include a complete blood cell count, measurement of the sedimentation rate, examination of the stool for occult blood as well as ova and parasites, and a lactose breath test. For patients with intractable symptoms or symptoms suggestive of inflammatory bowel disease, a colonoscopy may be indicated to detect evidence of mucosal inflammation. Once the diagnosis of irritable bowel syndrome has been made, the treatment is focused on education, reassurance, and the identification of possible psychosocial triggers. Studies evaluating the treatment of children with irritable bowel syndrome support the benefits of cognitive behavioral therapy, high-fiber diets, and peppermint oil. Other medications prescribed include antidiarrheals, anticholinergics, tricyclic antidepressants, and selective serotonin reuptake inhibitors.

Children with childhood functional abdominal pain experience episodic or continuous abdominal pain once per week for at least 2 months. The children categorized as having childhood functional abdominal pain do not meet the specific criteria for functional dyspepsia or irritable bowel syndrome. The pain described by these children is typically nonspecific, vaguely localized, often to the periumbilical area, and of variable severity. The abdominal pain onset of pain is gradual, with a clustering of episodes of pain that can last for weeks to months, occurring daily or several times per week. No consistent, temporal relationship to activity or meals is reported. The pain typically does not awaken children from sleep but can interfere with their daily functioning. These children may also experience other somatic symptoms, including nausea, headache, fatigue, and difficulty sleeping. Psychological stressors or “triggers” that precipitate symptoms may be identified and an associated family history of other chronic pain syndromes also may be elicited. However, it is important to recognize that a history of anxiety, depression, behavioral problems, and negative life events do not differentiate children with functional pain from those with an organic cause for their symptoms.

The physical examination findings and the results of laboratory studies in children with childhood functional abdominal pain are normal. In that functional abdominal lacks a specific diagnostic marker, the evaluation in these
children may be variable, depending on the presence or absence of “red flags,” duration and severity of pain, impact on daily life, and the level of concern. The laboratory evaluation of these patients may include a complete blood cell count, comprehensive metabolic profile, determination of the sedimentation rate, measurement of amylase and lipase levels, urinalysis, urine culture, examination of the stool for occult blood as well as ova and parasites, and lactose breath test. Abdominal and pelvic ultrasounds as a screening test in the absence of “red flags” have little diagnostic yield.

The diagnosis of childhood functional abdominal pain as well as other types of functional pain, is a positive diagnosis, not simply a reflection of an inability to “correctly” identify an underlying organic problem. Acknowledgment that the pain is real and not fabricated is particularly important in helping the patient and family. Treatment includes reassurance, and a discussion of visceral hypersensitivity, and the interaction of the enteric nervous system in children with functional abdominal pain. Identifying triggers, discussing the relationship between stress and symptoms, and limiting pain-induced disability are all beneficial. Cognitive behavioral therapy, relaxation techniques, and self-hypnosis have been shown to be effective in the treatment of children with functional abdominal pain. Medications also may be utilized selectively in the treatment of individual patients.

Common causes of abdominal pain include the following: