• Most patients will have idiopathic or functional constipation with no identifiable cause.
  • There is usually an acute event followed by chronicity.
• Hard stools cause anal pain or a fissure, leading to intentional or subconscious withholding.
  • This results in rectal dilatation, decreased sensation, shortening of the anal canal, decreased tone of the external anal sphincter, and leaking.
• Precipitating events include the following:
  • Transition from breast milk to cow’s milk in infants
  • Power struggle in toddlers
  • Refusal to use toilets outside the home
  • Streptococcal infection of the anus and perianal area
  • Transient viral illness (diarrhea followed by constipation)
  • Zealous toilet training
• Constipation also can be caused by anatomic anomalies in the lower gastrointestinal (GI) tract, decreased propulsion, impaired rectal sensation (primary or secondary), or a functional outlet obstruction (muscular spastic levator ani or impaired relaxation of the puborectalis).
• Neurologic causes (abnormalities of the myenteric plexus, intestinal pseudoobstruction, congenital aganglionosis, intestinal neuronal dysplasia), muscular diseases (familial and nonfamilial visceral myopathies), and lesions of the spinal cord result in loss of rectal tone and sensation and reduced anal closure, affecting the sacral reflex center (e.g., myelomeningocele, spina bifida occulta, tethered cord).
• Anatomic disorders of anus and rectum (stricture, stenosis, mass, ectopic anus, imperforate anus)
• Endocrine abnormalities (hypothyroidism), drugs, electrolyte abnormalities

• Retention of stool allows water to move out of stool, increasing size and firmness.
• Decreased motility will lead to retention of stool. See Causes.

• Anal fissures: Infrequent hard stools can cause a tear of the anal mucosa, causing pain and withholding.
• Encopresis: Chronic constipation leads to progressive rectal dilatation and decreased rectal sensation. Fecal impaction results with secondary soiling or encopresis.
• Intestinal obstruction manifests as vomiting, abdominal pain, and constipation, with abdominal x-ray (AXR) films showing intestinal obstruction and presence of large amounts of stool.
• Sigmoid volvulus: A chronically constipated child may present with symptoms of acute abdomen, fever, tender abdomen, and palpable mass. AXR shows obstruction in the colon. Barium enema may be both diagnostic as well as therapeutic by achieving reduction.
• Hirschsprung enterocolitis can occur in an infant with a history suspicious for Hirschsprung disease, who is now toxic, febrile with abdominal distention, and has bloody diarrhea. AXR can show a dilated colon.

• Hirschsprung disease: congenital aganglionic megacolon (i.e., the absence of ganglion cells)
• Neuromuscular causes: tethered spinal cord
• Anal abnormalities: anteriorly displaced anus, ectopic anus, imperforate anus
• Endocrine abnormalities: hypothyroidism and hyperparathyroidism
• Electrolyte imbalance: hypokalemia, hyponatremia, hypomagnesemia, hypercalcemia
• Lead ingestion: can present with anemia, constipation, and abdominal pain
• Infant botulism: constipation, aphonia, and weakness in a previously well infant
• Chronic intestinal pseudoobstruction syndrome: can present with abdominal distention, diarrhea, and constipation; usually a diagnosis of exclusion
• Abdominopelvic mass: can cause constipation by pressure (i.e., distended bladder or pelvic tumor)
• Surgical conditions: Malrotation, congenital intestinal bands, intestinal stenoses, acquired colonic strictures resulting from inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), pyloric stenosis
• Drugs: calcium supplements, barium, opiates; always get a careful drug history to avoid missing drug-related constipation.

Question: What is the timing of the passage of meconium?
Significance: If it is delayed for more than 24 to 48 hours, consider Hirschsprung disease.

Question: Is the child able to pass a bowel movement unaided by a suppository or enema?
Significance: If rectal stimulation is required for passage of a bowel movement, think of Hirschsprung disease or habituation to rectal stimulation.

Question: What are the size, frequency, and consistency of bowel movements?
Significance: One to three normal (in size and consistency) painless bowel movements may be passed every 1 to 3 days. The size of bowel movements reflects the caliber of the colon.

Question: Does the child experience frequent urination, bed wetting, or urinary tract infections?
Significance: These are seen frequently with chronic constipation.

Question: Is there soiling?
Significance: Soiling occurs if the stool is impacted or with nerve damage involving the anus.

Question: Is there presence of rectal sensation?
Significance: Patients with long-standing constipation or withholding who develop a dilated rectum will often lose the sensation of rectal distention.

Question: Is there a history of painful bowel movements or rectal fissure?
Significance: This could be the cause of withholding secondary to fear of painful bowel movements.

Some children are too busy playing to take the time to have a bowel movement. Some children do not want to use the toilet in school because of hygiene issues.

Question: Is the child experiencing any stressful events (i.e., new sibling, death in family)?
Significance: Stress can precipitate stool withholding, leading to constipation.

Question: Does the child have an unsteady or clumsy gait?
Significance: This may suggest neuromuscular problems.

Question: Did the child experience difficult toilet training?
Significance: Some children with encopresis have a history of difficult toilet training.

Question: What is the diet history for fluid, milk, caffeine, and fiber intake?
Significance: Excessive amounts of milk (calcium) and caffeine may be constipating in some individuals. Diets low in fiber and fluid can cause constipation.

• General: Look for evidence of systemic illness.
• Abdomen: Abdominal distension (indicative of the presence of stool or gas), presence of stool masses (size, location), distended bladder and bowel sounds (may be decreased in intestinal pseudoobstruction).
• Rectal examination: Perianal soiling, size and position of anus (may suggest imperforate or ectopic anus), presence of skin tags and fissures and perianal or anal erythema (streptococcal proctitis), or evidence of child abuse. On digital examination, assess anal tone (in functional constipation, anal tone is decreased; Hirschsprung disease may cause the anal canal to appear very long and tight), amount and consistency of stool, size of rectum (dilated rectum suggestive of chronic constipation; tight and empty anus suggestive of Hirschsprung disease), and presence of blood. Absence of anal wink suggests neurologic abnormalities.
• Neurologic examination: Check reflexes in the lower extremities.
• Back: Check for sacral dimple, tuft of hair (suggestive of underlying sacral abnormality), flat buttocks, and patulous anus.

• “Grunting baby syndrome”: Infants with this syndrome cry, scream, and draw up their legs during a bowel movement. They respond to rectal distention by contracting their pelvic floor. This is not constipation.
• Always rule out an organic cause for constipation.
• Compliance and good follow-up are key to successful management of functional constipation.

• Abdominal x-ray study: Look for presence and location of stool and evidence of bowel obstruction.
• Unprepped barium enema: useful in Hirsch-sprung disease; will show a narrow transition zone (affected bowel) with proximal dilated colon or small bowel, depending on extent of the disease. In very young infants, a transition zone may not be seen.
• Anorectal manometry: may be useful in Hirschsprung disease (failure of relaxation of the internal anal sphincter) and in patients with encopresis who do not respond to conventional therapy
• Suction rectal biopsy: useful in identifying patients with Hirschsprung disease. Absence of ganglion cells is suspicious; always needs to be confirmed by a full-thickness surgical rectal biopsy

• Clean-out: If patient is impacted, then a series of three to five enemas may be required, depending on the amount of retained stool. In general, children over 2 to 3 years of age require adult-size phosphate enemas. Younger children should get pediatric-size enemas. Oral or nasogastric polyethylene glycol solution (Go-Lytely) given over 6 to 8 hours may be used for clean-out. The solution is given until the effluent is clear.
• Stool softeners: Infants up to 1 year of age may be given dark Karo syrup or Maltsupex (1 tsp/8 oz of formula) several times a day. Children over 1 year of age may get mineral oil, lactulose, or milk of magnesia several times a day to soften stools and make their passage easier.
• Stimulant laxatives: Sennokot may be used as a stimulant for short periods of time. Long-term use has been associated with colonic nerve damage in adults.
• Diet: A high-fiber diet is recommended (toddler: 10–12 g/d; school-aged: 12–16 g/d; adolescent: 16–20 g/d). In some patients, caffeine and excessive milk-product intake may be constipating. Milk intake should be limited to 16 ounces a day.
• Toilet sitting: regular toilet sitting twice a day for 10 minutes, preferably after meals, to help retrain the bowel
• Calendar: It is important to keep a record of stools, accidents, toilet sitting, and medication intake. It is hard for parents to remember details, which may be important in identifying causes of failure.
• Fluid intake: High fluid intake is important.
• Biofeedback is helpful in patients who fail conventional therapy and have the following abnormalities on anorectal manometry: decreased sensory threshold to rectal distension, paradoxical contraction of the external anal sphincter and puborectalis muscle during simulated defecation.

• Encopresis (soiling or “diarrhea”): Abdominal x-ray (AXR) film shows large amounts of stool in the colon, including a dilated rectum. Disimpaction or clean-out, followed by treatment of constipation, is recommended (see above).
• Intestinal obstruction: vomiting, abdominal pain, and constipation. AXR film shows intestinal obstruction. Make NPO, give IV fluids, and rule out an acute abdomen. Then give enemas and clear out stool from below. Never give oral laxatives or a polyethylene glycol solution in a case of obstruction.
• Sigmoid volvulus: chronically constipated child with symptoms of acute abdomen, fever, tender abdomen, and palpable mass. AXR shows obstruction in the colon. Barium enema may reveal a volvulus and may reduce the volvulus.
• Hirschsprung enterocolitis: in an infant who presents with a history suspicious for Hirsch-sprung disease, who is now toxic, febrile with abdominal distention, and has bloody diarrhea. AXR shows dilated colon with or without a transition zone: NPO, IV fluids, antibiotics. Rectal tube and enemas are controversial. Obtain a surgical consult.

• Schedule regular visits to make sure therapy is maintained.
• Have parents call as soon as problems develop.
• Once patient is doing well, decrease the frequency of visits.

• Dietary measures: high-fiber diet, plenty of fluids, avoidance of excessive caffeine intake

Q: When is constipation an emergency?
A: When intestinal obstruction, sigmoid volvulus, or Hirschsprung enterocolitis occur.

Abi-Hanna A, Lake AM. Constipation and encopresis in childhood. Pediatr Rev 1998;19(1):23–30; quiz 31.

Loening-Baucke V. Chronic constipation in children. Gastroenterology 1993;105:1557–1564.

Seth R, Heyman MB. Management of constipation and encopresis in infants and children. Gastroenterol Clin North Am 1994;23(4):621–636.

Staiano GS. The long term follow up of children with chronic idiopathic constipation. Arch Dis Child 1992;67:340.