DESCRIPTION

Constipation is the inability to pass stool or withholding stool in the colon. Rome IV criteria for functional constipation diagnosis must include 2 or more of the following occurring at least once per week for a minimum of 1 month with insufficient criteria to diagnose irritable bowel syndrome, and after appropriate evaluation, the symptoms cannot be fully explained by another medical condition:

• 2 or fewer defecations in the toilet per week in a child of developmental age of at least 4 years old
• At least 1 episode of fecal incontinence per week
• History of retentive posturing or excessive volitional stool retention
• History of painful or hard bowel movements
• Presence of a large fecal mass in the rectum
• History of large diameter stools that can obstruct the toilet

EPIDEMIOLOGY

• Prevalence of constipation in children is estimated to be a mean of 14%.
• There is an increased incidence around toilet training. There appears to be an increased prevalence of constipation associated with lower socioeconomic status and lower level of parental education.
• Incidence between sexes is similar; however, boys with constipation tend to have higher rates of fecal incontinence compared to girls.

ETIOLOGY

• Majority of patients have idiopathic or functional constipation with no identifiable cause.
• Intentional stool withholding due to fear, access to bathroom, sexual abuse, or other reasons
• Precipitating events may include the following:
  • Transition from breast milk to cow’s milk
  • Excessive cow’s milk intake
  • Insufficient water and/or fiber intake
  • Passage of hard/painful stool
  • Rectal fissure
  • Refusal to use toilets outside the home
  • Premature toilet training
  • Perianal dermatitis
• Neurologic causes:
  • Abnormalities of the myenteric plexus
  • Intestinal pseudo-obstruction
  • Congenital aganglionosis (Hirschsprung disease)
  • Nonrelaxing internal anal sphincter (internal anal sphincter achalasia)
  • Lesions of the spinal cord
• Anatomic disorders of anus and rectum (stricture, stenosis, mass, ectopic anus, imperforate anus, fistula)
• Endocrine abnormalities (hypothyroidism)
• Medications (opiates, anticholinergics, antidepressants)
• Heavy metal ingestion (lead)
• Electrolyte abnormalities

RISK FACTORS

Risk factors for constipation include the following:

• Low-fiber diet
• Positive family history of constipation
• Stress or anxiety
• Living in urban areas
• Underlying comorbidities such as cystic fibrosis or autism spectrum disorder

GENERAL PREVENTION

• Maintain adequate fluid intake
• Consume a high-fiber diet with fruits and vegetables.
• Engage in regular physical activity.
• Encourage regular attempts to pass stool and/or remind child to respond to urge to defecate.

PATHOPHYSIOLOGY

• Delay in colonic passage and/or retention of stool allows fluids mixed in stool to be resorbed across cellular membranes, causing a harder caliber stool that is more difficult and painful to pass.
• Painful stools may increase intentional withholding
• Rectosigmoid enlargement over time due to retained stool diminishes sensation to stool.
• An enlarged colon has decreased force to propel stool forward, further worsening the fecal burden.

COMMONLY ASSOCIATED CONDITIONS

• Hirschsprung disease
• Celiac disease
• Hypothyroid
• Diabetes mellitus
• Spinal cord lesions
• Autism spectrum disorder
• Cystic fibrosis
• Irritable bowel syndrome
• Disorders causing hypotonia such as muscular dystrophy
• Abnormal abdominal musculature such as prune belly, gastroschisis, Down syndrome