Pediatric Constipation

Overview

Definition

• Constipation is a relative term and depends on a number of factors including frequency, consistency, and difficulty in passage of stool:
  • A hard stool (consistency) passed every 3rd day (frequency) with “difficulty” requires management. 
  • A soft stool that is passed without difficulty every 2–3 days is not constipation.
• The Paris Consensus on Childhood Constipation Terminology (PACCT) definition:
  • A period of 8 weeks with at least 2 of the following symptoms: 
    • Defecation < 3/week 
    • Fecal incontinence 2 ⩲/week 
    • Passage of large stools that clog the toilet 
    • Palpable abdominal or rectal fecal mass 
    • Habit of withholding stool
    • Painful defecation

Epidemiology

• Constipation of all etiologies:
  • Affects 30% of children
  • Makes up approximately 4% of pediatrician visits
  • Most common in 2–4-year-old children
• Functional constipation:
  • Constitutes 95% of all cases of constipation
  • Most common in preschool-aged children

Etiology

• Functional constipation:
  • Meets clinical PACCT criteria for constipation with no underlying pathologic causes
• A minority (about 5%) may have constipation due to organic causes.

Pathophysiology

Functional constipation is the most common cause of constipation:  

• Causative psychologic vicious cycle 
• Dietary or environmental factors lead to hardened stool → more painful to pass.
• Bowel movements associated with pain →  withhold defecation
• Chronic stool holding → accommodation by the rectum and further hardening of stool
• Reduced sensitization to defecation reflex and less effective peristalsis
• Encopresis (inability to hold stool): 
  • Passage of proximal watery content around compacted stool 
  • May be mistaken for diarrhea
• May rarely cause urinary stasis
• Chronic severe constipation may have an emotional impact on the patient and family.

Clinical Presentation and Diagnosis

History and exam are performed to rule out any organic causes and reassure the provider that the symptoms in question are due to functional constipation.

History

Toileting patterns:

• Frequency, consistency, size of stools, pain, and association with bleeding are important defining and etiologic clues.
• Fecal incontinence or diarrhea may indicate encopresis.
• History of frequent urinary tract infections may indicate constipation-induced urinary stasis or vesicoureteral reflux.

Timing of onset of symptoms:

• Dietary transition
• Recent severe illness, dehydration, or diaper rash

Psychosocial stressors:

• Starting a new school
• Family changes (moving, birth of new sibling, or divorce)
• Toilet training

Behavioral cues:

• Squatting 
• Crossing ankles
• Stiffening the body
• Holding onto furniture

Cues pointing to organic etiologies:

• Hirschsprung’s disease:
  • Passage of meconium (1st bowel movement) delayed for more than 24 hours
  • Constipation during early months after birth
• Lead poisoning:
  • Pica
  • Developmental delay
  • Living in older home or home with lead-based paint
• Dietary intolerances (e.g., milk protein intolerance, celiac disease):
  • Recent transition from breastfeeding to solid food
  • Transition from breast milk to cow milk–based formula
  • Intermittent blood noted in stool

Physical examination

General:

• Growth charts should be reviewed to ascertain appropriate growth: Failure to thrive suggests organic causes of constipation. 
• Dysmorphia and other cues to syndromes should be noted:
  • Down’s syndrome
  • Prune belly syndrome
• Prenatal history suggestive of Hirschsprung’s disease should be reviewed.

Abdominal exam:

• Palpation of left lower quadrant may reveal stool mass.
• Auscultation may reveal hyperactive bowel sounds.

Rectal exam:

• Anal abnormalities may suggest an underlying pathology:
  • Abnormal position of the anus suggests anal atresia.
  • Presence of perineal or sacral dimples or hair tufts suggests spina bifida or a tethered cord.
  • Anal fissures or fistulas
  • Hemorrhoids should be noted on inspection.
• Failure to elicit an anal wink (transient contraction) by stroking the perianal skin may indicate sensory or motor nerve abnormalities:
  • Spinal cord lesions
  • Tethered cord
  • Autonomic neuropathy
  • Spinal cord trauma
  • Spina bifida
  • Chagas disease
• Digital rectal examination: 
  • Large, firm stool mass in the rectum in many patients with functional constipation
  • Small, empty rectum in Hirschsprung’s disease
  • A gush of liquid stool may occur following a digital rectal exam in patients with Hirschsprung’s disease. 

Neurologic exam: 

• Absent cremasteric reflex (pulling up of the ipsilateral testicle while stroking the thigh in boys) 
• Abnormal tone of the lower extremity: muscular dystrophy 

Diagnosis

In an otherwise healthy child, functional constipation is diagnosed clinically. Laboratory examination should be directed by cues suggesting other pathologic causes:

• Laboratory testing: not indicated unless an organic cause is suspected
• Abdominal radiographs: 
  • Not performed routinely
  • In special circumstances, radiographs may show a burden of a stool mass, especially when overflow diarrhea is suspected or physical examination is refused.
• Single-contrast enema (not air-contrast enema) with abdominal radiographs: 
  • May assist in the diagnosis of Hirschsprung’s disease 
  • Transitional zone from a narrow (aganglionic) distal segment to a distended (ganglionic) proximal segment is consistent with the diagnosis.
• Anorectal manometry: 
  • A rectal balloon is inserted and inflated to measure rectal pressure.
  • Can be helpful in diagnosing neurologic causes of constipation 
• Rectal biopsy: Absent ganglionic cells in the affected colon confirms a diagnosis of Hirschsprung’s disease.

Management

• If an organic cause is identified, management is tailored to the specific etiology. 
• In patients with functional constipation, management centers around 3 components:
  • Evacuation of colon: 
    • Oral cathartics (lactulose, magnesium hydroxide) 
    • Enemas (saline solution ± glycerin) 
  • Elimination of pain upon defecation: 
    • Chronic sufficient laxative therapy is safe and effective.
    • Dietary modifications, such as increased intake of fluids, complex carbohydrates (fruit juice), and vegetables with removal of cow milk in very young children
  • Improving bowel habits: Regular, 5–10-minute visits to the toilet, preferably after breakfast and supper, should be encouraged. 
• Surgery is rarely needed.
• Further recommendations:
  • Promote breastfeeding in neonates.
  • Recommend a reward-focused behavior change and the avoidance of chastising the child for their toileting behavior.