Causes of Chronic Constipation in Children
Chronic constipation in children is predominantly functional (approximately 95% of cases) without an identifiable organic cause, but you must systematically rule out serious underlying conditions before settling on this diagnosis. 1, 2
Functional Causes (Most Common)
Functional constipation accounts for the vast majority of cases and results from learned behavior, perpetuation of infantile voiding patterns, or maturational delay. 3, 1 This is a clinical diagnosis based on symptoms including:
- Infrequent defecation (typically fewer than 3 bowel movements per week) 3
- Painful or hard bowel movements with large diameter stools 4
- Fecal incontinence and withholding behaviors 5, 1
- Sensation of incomplete evacuation or anorecal blockage 3
The pathophysiology involves a vicious cycle where painful defecation leads to stool withholding, which causes harder stools and perpetuates the problem. 1, 2
Organic Causes Requiring Exclusion
Anatomic and Neurologic Disorders
Hirschsprung disease is the most critical anatomic cause to exclude, particularly in infants, as it requires surgical intervention. 1, 2 Red flag signs include:
- Delayed passage of meconium beyond 48 hours of life 1
- Failure to thrive with early onset constipation 1
- Explosive stools after rectal examination 2
Spinal cord abnormalities and tethered cord syndrome cause constipation through impaired bowel innervation. 3 Look for:
- Associated cutaneous markers on the lower back (dimples, tufts of hair, hemangiomas) 3
- Progressive neurologic symptoms including sensorimotor disturbances of lower limbs 3
- Bladder dysfunction, urinary incontinence, or recurrent urinary tract infections 3
- Orthopedic deformities, scoliosis, or gait disturbances 3
- History of being "slow" athletically or late toilet training 3
Metabolic and Endocrine Disorders
Screen for metabolic causes including hypercalcemia, hypothyroidism, hypokalemia, and diabetes mellitus, as these are treatable conditions that can present with constipation. 3, 4, 6
Genetic Syndromes
Williams syndrome is associated with chronic lifelong constipation requiring aggressive treatment. 3 Complications in this population include rectal prolapse, hemorrhoids, intestinal perforation, and early-onset diverticulitis in adolescents. 3
Cystic fibrosis can present with constipation and should be considered, particularly with other gastrointestinal symptoms or failure to thrive. 1
Medication-Induced
Opioid-induced constipation requires specific management with stimulant laxatives with or without stool softeners. 4
Dysfunctional Voiding and Pelvic Floor Disorders
Dysfunctional voiding (dysfunction during the voiding phase) results from paradoxical contraction or incomplete relaxation of the pelvic floor and external anal sphincter during defecation. 3 This creates:
- Staccato or plateau-shaped flow patterns on uroflowmetry 3
- Incomplete bladder emptying and increased urinary tract infections 3
- Strong association with constipation—treating constipation alone resolves bladder emptying in 66% of affected children 3
In children with both constipation and urinary symptoms, treating the constipation first is critical, as 89% achieve resolution of daytime wetting and 63% resolution of nighttime wetting after constipation treatment alone. 3
Urologic Associations
Bladder dysfunction and urinary tract abnormalities frequently coexist with constipation. 3 In Williams syndrome specifically:
- 50% have bladder diverticula 3
- 60% have detrusor overactivity leading to urinary frequency 3
- 25% have history of urinary tract infections 3
Critical Pitfall to Avoid
Do not assume functional constipation without performing a digital rectal examination to assess for fecal impaction, anal tone abnormalities, or anatomic issues. 4, 6 The presence of impaction changes your immediate management approach, and abnormal anal tone or absent anal wink reflex suggests neurologic pathology requiring further workup. 1, 2
Aggressive treatment of constipation is essential regardless of cause, as chronic untreated constipation leads to serious complications including rectal prolapse, hemorrhoids, intestinal perforation, and in certain populations like Williams syndrome, early diverticulitis. 3, 4, 6