DESCRIPTION

Delay or difficulty in defecation; infrequent (<2) stools per week; defecation resulting in pain and/or rectal bleeding, and/or fecal soiling; may also refer to a decrease in frequency of bowel movements compared with the patient’s usual bowel pattern

GENERAL-PREVENTION

• Maintain adequate fluid intake.
• Consume a high-fiber diet with fruits and vegetables.
• Avoid excessive caffeine and milk (calcium) intake.
• Engage in regular physical activity.

PATHOPHYSIOLOGY

• Delay in colonic passage and/or retention of stool allows fluids mixed in stool to be resorbed across cellular membranes, increasing stool caliber and leading it to be harder in consistency.
• Decreased motility leads to a buildup of desiccated stool causing painful defecation, which is a risk factor for ongoing stool retention.
• As the rectosigmoid enlarges over time with retained stool, a child’s ability to sense rectal fullness diminishes, and he or she may not appreciate the need to defecate.
• Often, there is a family history of motility disturbances or constipation.

ETIOLOGY

• Most patients have idiopathic or functional constipation with no identifiable cause.
• Personal history of constipation may be traceable to an acute event (i.e., passage of large, painful stool) followed by chronicity.
• Intentional or unintentional withholding of stool may result in hard stools, anal pain, and fissures that perpetuate and lead to constipation. Rectal dilatation, decreased sensation of the urge to defecate, shortening of the anal canal, decreased tone of the external anal sphincter, and encopresis can result.
• Precipitating events may include the following:
  • Transition from breast milk to cow’s milk
  • Excessive cow’s milk intake
  • Insufficient water intake
  • Refusal to use toilets outside the home
  • Premature toilet training
  • Perianal streptococcal infection
  • Food allergies
  • Transient viral illness (diarrhea followed by constipation)
• Constipation also can be caused by anatomic anomalies in the lower GI tract, decreased propulsion, increased rectal sensitivity threshold, 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 (Hirschsprung disease)
  • Nonrelaxing internal anal sphincter
  • Visceral neuropathies
  • Visceral myopathies
  • Familial dysautonomia
• Lesions of the spinal cord can result in loss of rectal tone and sensation and reduced anal closure, affecting the sacral reflex center (e.g., meningocele, myelomeningocele, tethered cord, schwannoma).
• Anatomic disorders of anus and rectum (stricture, stenosis, mass, ectopic anus, imperforate anus, fistula)
• Endocrine abnormalities (hypothyroidism), drugs, and electrolyte abnormalities