Abdominal Pain, Chronic

Kristin N. Fiorino

DIFFERENTIAL DIAGNOSIS LIST

Neonate/Toddler

Functional

Infant colic
Infant dyschezia
Infant regurgitation
Eosinophilic gastroenteritis
Gastroesophageal reflux disease
Milk-protein allergy

Child/Adolescent

Functional

Abdominal migraine
Appendiceal colic
Childhood functional abdominal pain
Childhood functional abdominal pain syndrome
Functional dyspepsia
Intestinal pseudo-obstruction
Irritable bowel syndrome
Functional constipation

Inflammatory Causes

Chronic cholecystitis
Chronic pancreatitis, with or without pseudocyst
Inflammatory bowel disease (IBD)
Non-Helicobacter pylori-mediated esophagitis, gastritis, and peptic ulcer disease (reflux, nonsteroidal anti-inflammatory drugs, corticosteroids, etc.)

Infectious Causes

Giardia lamblia enteritis and other parasitic infections
H. pylori-mediated esophagitis, gastritis, and peptic ulcer disease
Vertebral infection—diskitis and osteomyelitis

Anatomic/Mechanical Causes

Abdominal muscle strain
Choledochal cyst
Cholelithiasis
Chronic nephrolithiasis
Hematoma, intra-abdominal
Hernia, internal
Intestinal duplication
Malrotation with or without volvulus
Musculoskeletal
Slipping-rib syndrome
Ureteropelvic junction obstruction

Gynecologic Causes

Cystic teratoma
Dysmenorrhea
Endometriosis
Hematometrocolpos
Mittelschmerz

Toxic Causes

Lead poisoning

Systemic Causes

Abdominal tumor—Wilms tumor and neuroblastoma
Acute intermittent porphyria
Carbohydrate intolerance/malabsorption
Celiac disease
Chronic Henoch-Schönlein purpura
Collagen vascular disease
Hepatitis
Hereditary angioedema
Leukemia
Lymphoma, including gastrointestinal (GI) tract lymphomas
Sickle cell disease
Spinal column tumor (e.g., leukemia, osteosarcoma)

Neurologic/Psychiatric

Conversion reaction
Depression
Factitious

DIFFERENTIAL DIAGNOSIS DISCUSSION

Chronic abdominal pain is one of the most commonly encountered symptoms in pediatrics. The definition has evolved since the 1950s when Apley described it as intermittent abdominal pain in children between the ages of 4 and 16 that is present for >3 months and affects daily activity. In clinical practice, pain lasting >2 months is considered to be chronic. Prevalence studies indicate that as many as 20% of middle and high school students experience frequent abdominal pain. Approximately 90% of these children have functional or nonorganic abdominal pain, pain without demonstrable evidence of a pathologic condition, such as an infectious, inflammatory, anatomic, or biochemical mechanism. The remaining children have organic abdominal pain, whose most common causes are described in detail here.

Abdominal Pain in Infants/Toddlers

Infant Colic

Infant colic is a functional GI disorder in an infant >4 to 5 months without a clear organic basis. While the term “colic” implies abdominal pain secondary to obstruction of blood flow from an organ such as the kidney, gallbladder, or intestine, “infant colic” is a behavioral syndrome incorporating bouts of crying and difficult-tosoothe behavior that is usually influenced by psychosocial issues in a family. No clear evidence indicates that colic pain is from GI organs or from any other body part. Nonetheless, it is often assumed that the cause of the excessive colic is GI in origin.

Etiology

Colic, when referring to the prolonged crying seen in infancy, is technically defined as colic syndrome. The definition of infantile colic has evolved from the seminal definition by Wessel in the 1950s to include paroxysms of crying, irritability or fussiness lasting >3 hours/day and occurring at least 3 days/week for >1 week. Organic etiologies such as failure to thrive need to be excluded. The etiology of colic is not well understood, and the mechanisms proposed to cause it are at best vague. The immaturity of the infant nervous system may play a role, particularly the transitioning to a more awake state. The gradual decrease in colic symptoms coincides with the acquisition of skills that enable the infant to more adequately maintain a calm awake state. Behavioral factors such as burping abnormalities or crying while feeding leading to ingested air (aerophagia) are suggested; however, it is argued that intestinal gas is a result of colic rather than a cause. Baseline motilin levels are raised, suggesting that increased gastric emptying increases small-bowel peristalsis leading to perceived intestinal pain. Other proposed etiologies include intolerance to cow’s milk, although little evidence indicates that children with colic have true milk protein intolerance, and the symptoms of that disorder do not include colic-like symptoms.

Evaluation

The crying noted in colic typically peaks in the evening at the age of 6 weeks, generally tapering off by 3 to 4 months of age. Other features include movements and facial features interpreted as being consistent with pain, as well as GI symptoms such as gas and abdominal distention. Clearly, these criteria are loose and may fall within the realm of normal infant behavior, albeit at one end of the curve. Physical and laboratory examinations of children with colic are uniformly normal.

Treatment

Treatment of colic is designed to relieve the parents’ stress. Infants in this age range are targets of abuse, and preventing overstressed parents from harming these children is an important goal. Advice to parents of an infant with colic should always include suggestions on how to manage the stress, such as taking a brief break from caregiving. Reassurance that the crying will eventually stop is helpful. Environmental changes that facilitate the awake state and reduce crying, such as increasing rhythmic rocking, using a pacifier, increasing background white noise with a vacuum cleaner or washing machine, or taking a ride in the car or stroller, may be helpful. Antispasmodics and anticholinergics are not indicated for use in infants because they are associated with respiratory distress and apnea. Changing from breast- to formula-feeding is not indicated, and switching formulas should only be done if there is a suggestion of true milk-protein intolerance.

Infant Dyschezia

Etiology

Infant dyschezia is defined as a functional GI disorder. It is characterized by otherwise healthy infants <6 months of age experiencing at least 10 minutes of straining and crying before successful passage of soft stools. Infant dyschezia is secondary to failure to coordinate increased intra-abdominal pressure with pelvic floor relaxation. Crying is analogous to creating increased abdominal pressure (Valsalva maneuver) prior to learning how to coordinate and bear down more effectively.

Evaluation and Treatment

Parents describe screaming, crying, and turning red or purple in the face with effort prior to defecation. Physical examination, which should be performed in the presence of the parents to help promote effective reassurance, is normal, inclusive of rectal examination. Diagnostic tests are not required. Avoidance of rectal stimulation is advised to negate artificial sensory experiences. Infant dyschezia rarely lasts >1 to 2 weeks and responds spontaneously.

Infant Regurgitation

Etiology

Uncomplicated regurgitation of food in otherwise healthy infants aged 3 weeks to 12 months is a functional GI disorder. It is defined as regurgitation two or more times per day for >3 weeks without evidence of pathologic symptoms such as apnea, failure to thrive, aspiration, feeding difficulties, retching, or hematemesis. When regurgitation contributes to tissue damage or inflammation of the esophagus, it is known as gastroesophageal reflux disease.

Evaluation and Treatment

Parents usually describe irritability or arching of the back after feeds. Regurgitation occurs in more than two-thirds of healthy 4-month-old infants. Daily regurgitation decreases with age to 5% of infants 10 to 12 months of age. Risk factors include abnormalities of the chest, lungs, central nervous system, oropharynx, heart, or GI tract. Milk allergy may be present, especially if associated with eczema or wheezing and may require switching of infant formula. The natural history of infant regurgitation suggests spontaneous improvement. Left-sided positioning and thickening of feeds may help reduce symptoms. Improving the parent—child relationship and decreasing familial stress are ways to help provide effective reassurance. Gastroesophageal reflux in infants is treated with acid blockade, most commonly a histamine₂-receptor antagonist.

ABDOMINAL PAIN IN CHILD/ADOLESCENT

Children with functional GI disorders typically exhibit one of the three clinical presentations, including isolated paroxysmal abdominal pain, abdominal pain associated with dyspepsia, and abdominal pain associated with irritable bowel syndrome as specified by the Rome III criteria and described here and in Table 10-1. Also included in functional disorders are abdominal migraine, appendiceal colic, and functional constipation. Chronic intestinal pseudo-obstruction is a defect in bowel intestinal motility. Approximately 20% of school-age children, most commonly 4 to 16 years of age, are believed to have some variety of functional abdominal pain. The mean age of onset is between 4 and 8 years of age, with boys and girls affected equally until 9 years of age, at which point more girls are affected. Onset >14 years is usually associated with symptoms more consistent with irritable bowel syndrome, whereas onset <4 years has a greater chance of an organic etiology. Although psychological factors are important, there is no correlation of functional abdominal pain with personality traits such as perfectionism or chronic worrying.

Etiology

The factors that produce functional abdominal pain are not entirely clear. Pathophysiologic studies have focused on the autonomic nervous system and GI motility, suggesting a role for altered gastric motility and heightened visceral sensitivity to intestinal contractions in individuals with functional abdominal pain. Although psychological factors do not distinguish organic from nonorganic etiology, correlation with various psychosocial factors, such as family stress, are described. Often there is a family history of alcoholism, behavioral problems, abdominal pain, or migraine headaches. The family dynamic in response to the pain is important as well, as often there is positive reinforcement for having abdominal pain, ranging from emotional support to excusing from school or household chores.

TABLE 10-1 Rome Criteria for the Diagnosis of Functional Abdominal Pain in Children with Pain at Least Once per Week for at Least 2 Months Prior to Diagnosis

Childhood Functional Abdominal Pain	Childhood Functional Abdominal Pain Syndrome	Functional Dyspepsia	Irritable Bowel Syndrome
Episodic or continuous abdominal pain	Episodic or continuous abdominal pain 25% of the time	Persistent or recurrent pain or discomfort in the upper abdomen (above the umbilicus)	Abdominal pain or discomfort at least 25% of the time with two or more of the following: relief with defecation, onset associated with a change in frequency, or onset associated with a change in stool consistency
No structural or biochemical abnormalities to explain the symptoms	Some loss of daily functioning	Symptoms not relieved by defecation or associated with the onset of a change in stool frequency or stool form	Associated with abnormal stool frequency (≥2 times/wk or >4 times/d), alternating stool character, straining, urgency, passing mucus, bloating, and distension
The child does not satisfy criteria for another type of functional abdominal pain	Somatic systems such as headache, limb pain, or difficulty sleeping	No structural or biochemical abnormalities to explain the symptoms	No structural or biochemical abnormalities to explain the symptoms
	No structural or biochemical abnormalities to explain the symptoms

Childhood Functional Abdominal Pain

Childhood functional abdominal pain is defined as episodic or continuous pain that occurs at least once per week for at least 2 months prior to diagnosis without a clear organic etiology. Childhood functional abdominal pain syndrome includes functional abdominal pain at least 25% of the time and either some loss of daily functioning or somatic symptoms such as headaches, limb pain, or difficulty sleeping. Pain is usually generalized or periumbilical, lasts <1 hour, and does not have a temporal relation to meals.

Functional Dyspepsia

Functional dyspepsia is defined as persistent or recurrent abdominal pain or discomfort centered above the umbilicus and not relieved by defecation or associated with changes in stool frequency or consistency. There is no evidence of an underlying etiology including an inflammatory, anatomic, metabolic, or neoplastic process that can explain the symptoms that need to be present at least once per week for at least 2 months prior to diagnosis. Often there is a temporal relation between meal ingestion and symptoms. Commonly associated symptoms include nausea, early satiety, postprandial abdominal distention, and excess gas.

Irritable Bowel Syndrome

Irritable bowel syndrome is characterized by abdominal discomfort or pain occurring at least 25% of the time without an underlying etiology and two of the following: improvement with defecation, a change in stool frequency, or a change in stool consistency. The symptoms are present at least once per week for at least 2 months prior to diagnosis. Irritable bowel is usually associated with autonomictype symptoms and environmental stress, as is isolated functional abdominal pain.

Evaluation

Functional abdominal pain is categorized by the different constellation of symptoms. The pain of functional abdominal pain is recurrent and paroxysmal. There is typically a clustering of the pain episodes within days or weeks that waxes and wanes over the course of months. The pain is often difficult for the child to describe and often not associated with eating or other activities but frequently occurs at the same time of day and usually lasts <1 hour. The presence of alarming symptoms such as weight loss, melena, and other red flags listed in Table 10-2 suggests the presence of an organic etiology to the pain.

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