Constipation is a common pediatric disorder, with studies citing a prevalence up to 30% with a median of 9% of children;¹ however, in special patient populations such as children with cerebral palsy, prevalence is much higher.² It was the principal diagnosis in 52/10,000 hospital discharges for patients <18 years old with an all-study mean cost per discharge of $17,518 in 2010.³ Because normal stooling patterns vary greatly among individuals and by age, constipation is generally defined as infrequent or difficult passage of hard stool, frequently associated with pain and straining.^1,4-8 Average stooling frequencies at different ages have been defined (Table 76-1).

Constipation can occur at any age but is particularly common in toddlers and elementary school–age children. In most studies, no significant gender-specific prevalence difference has been reported.¹

The causes of constipation can be divided into anatomic, physiologic, and functional (Table 76-2). Anatomic causes of constipation include Hirschsprung disease, imperforate anus, and bowel obstruction. Physiologic causes include a number of processes that alter bowel motility, such as hypothyroidism and spinal cord defects. Functional constipation, which results from voluntary stool withholding, is the most common cause of constipation (90%–97% of cases) and is often a self-perpetuating condition that starts with an episode of pain on defecation, a battle over toilet training, or toilet phobia.^1,4,5,7,9,10 Functional constipation may progress to encopresis, which is either voluntary or involuntary fecal incontinence in a child at least 4 years of age. It can involve leakage of stool around more distal, firm fecal impaction and is thought to result from chronic constipation secondary to functional fecal retention.

Indications for hospitalization include failure of outpatient management to resolve excessive stool burden or inability to maintain adequate intake due to associated vomiting or abdominal pain.

Constipation does not always present with the obvious history of infrequent or hard stools. Children may have regular, even daily, bowel movements but incomplete evacuation leading to progressive stool retention. The presenting complaint is often abdominal pain, which may be intermittently severe but is typically low grade and difficult for the child to describe. The location of the pain is usually periumbilical, and on examination there may be tenderness but usually no rebound or guarding. Other manifestations of constipation include diarrhea as with encopresis, also abdominal distention, anorexia, flatulence, dyschezia, blood-streaked stools, nausea, and vomiting, and constipation can even progress to bowel obstruction.

Constipation is often diagnosed easily and with specificity by the presence of infrequent or hard stools. However, there is a large differential diagnosis of underlying disorders that can lead to constipation (see Table 76-2). Although functional constipation is the most common type, it is important to keep other disorders in mind, especially in children with complex medical needs, recurrent constipation, or new onset of constipation.

The diagnosis and evaluation of constipation rests on a thorough history and physical examination. History alone may differentiate those children with an organic cause of constipation from those with functional constipation (Table 76-3). Besides stool consistency and frequency, the history should include time to passage of the first meconium stool, age at onset of symptoms, details of toilet training, urinary retention or incontinence and associated symptoms of rectal pain and bleeding, abdominal pain, and stool incontinence. An evaluation of other constitutional symptoms, such as fevers, weight loss, and nausea should also be considered for those who have an acute or subacute onset of symptoms and those with severe enough symptoms to require hospitalization, as they may suggest an underlying organic disorder. A history of delayed passage of the first stool beyond 48 hours of life raises the suspicion of Hirschsprung disease, as would a longstanding family or personal history of constipation. A history of stool withholding or of constipation associated with toilet training or toilet phobia is strongly suggestive of functional constipation.

A careful and thorough physical examination can help identify underlying disorders. For all children with constipation, there may or may not be abdominal distension present or palpable stool in the abdomen. For children with functional constipation, a large rectal impaction may be found on digital rectal examination, but the remainder of the physical examination should be normal, including normoactive bowel sounds and no significant focal tenderness. Hirschsprung disease may be suggested by an empty, non-distended rectum or by expulsion of gas and stool following a digital rectal examination. Inspection of the anus may reveal imperforate anus or anal stenosis, and fissures may be detected in those with a complaint of bloody stools. Bowel obstruction, which can be caused by constipation or can lead to constipation, should be associated with abdominal distension along with persistent vomiting and inability to tolerate food or liquids, and auscultation may reveal tinkling or hypoactive bowel sounds. On neurologic examination, deep tendon reflexes may be sluggish in hypercalcemia and hypothyroidism, or hyperreflexic in spinal cord abnormalities. Lower extremity weakness or an absent anal wink are suggestive of a neurologic cause of constipation. Examination of the lumbosacral area of the spine may reveal a hairy patch, sinus tract, or other midline defect which could suggest spina bifida.