eMedicine Specialties > Pediatrics: General Medicine > Gastroenterology

Constipation

Author: Stephen Borowitz, MD, Professor of Pediatrics and Public Health Sciences, Department of Pediatrics, Division of Gastroenterology and Nutrition, University of Virginia
Contributor Information and Disclosures

Updated: Jul 15, 2008

Introduction

Background

Concern about bowel function has been prevalent throughout history across many cultures. A normal bowel pattern is thought to be a sign of good health. Unfortunately, no uniform definition of childhood constipation is recognized. Moreover, health care providers have definitions of constipation that are very different than most parents' definitions. 

The North American Society of Gastroenterology and Nutrition defines constipation as "a delay or difficulty in defecation, present for 2 weeks or more, and sufficient to cause significant distress to the patient."¹  The Paris Consensus on Childhood Constipation Terminology defines constipation as "a period of 8 weeks with at least 2 of the following symptoms: defecation frequency less than 3 times per week, fecal incontinence frequency greater than once per week, passage of large stools that clog the toilet, palpable abdominal or rectal fecal mass, stool withholding behavior, or painful defecation."²  For practical clinical purposes, constipation is generally defined as infrequent defecation, painful defecation, or both. In most cases, parents are worried that their child's stools are too large, too hard, not frequent enough, and/or painful to pass.

Constipation in children is an extremely common problem with reported prevalence rates between 4-37%. Constipation is the principal complaint in 3-5% of all visits to pediatric outpatient clinics and as many as 35% of all visits to pediatric gastroenterologists.³

Pathophysiology

Most children with constipation have no underlying medical condition. They are often labeled as having functional constipation or acquired megacolon. In most cases, childhood constipation develops when the child begins to associate pain with defecation. Once pain is associated with the passage of bowel movements, the child begins to withhold stools in an attempt to avoid discomfort. As stool withholding continues, the rectum gradually accommodates, and the normal urge to defecate gradually disappears. The infrequent passage of very large and hard stools reinforces the child's association of pain with defecation, resulting in worsening stool retention and progressively more abnormal defecation dynamics with anal sphincter spasm. Chronic rectal distension ultimately results in both loss of rectal sensitivity, and loss of the urge to defecate, which can lead to fecal incontinence (ie, encopresis).

The differential diagnosis of childhood constipation can be extensive and may include Hirschsprung disease (ie, congenital megacolon), spinal or neuromuscular abnormalities, hypothyroidism, anal stenosis, imperforate anus with fistula, anterior displacement of the anus (this is a controversial diagnosis), allergy or sensitivity to cow's milk, and celiac disease. Fortunately, in most cases in which an underlying condition causes constipation, other stigmata of the disorder point to diagnosis. For example, constipation is rarely the only symptom of hypothyroidism.

For practical purposes, in an otherwise healthy child, the differential diagnosis of chronic constipation is Hirschsprung disease and functional constipation (not Hirschsprung disease). Although this differentiation sometimes may be difficult, a number of clues in the history and physical examination are helpful (see Media file 1).

Frequency

United States

Constipation is extremely common among infants and young children. Issenman et al found that 16% of parents reported that their 2-year-old children had constipation.⁴  Loening-Baucke reported that the prevalence of constipation was 22.6% among 482 children aged 4-17 years.⁵ In a longitudinal study of children aged 9-11 years, Saps et al reported an 18% overall prevalence of constipation.⁶

International

Yong and Beattie found that 34% of parents in the United Kingdom reported their children aged 4-7 years had at least intermittent difficulties with constipation.⁷ de Araujo Sant'Anna and Calcado found that 28% of Brazilian children aged 8-10 years were constipated.⁸

Sex

Before puberty, constipation appears to be equally common among girls and boys. After puberty and into young adulthood, females are more likely to develop constipation.

Age

Constipation occurs in all pediatric age groups from infancy to young adulthood. Typically, childhood constipation develops during 3 stages of childhood: in infants during weaning, in toddlers during toilet training, and in school-aged children. In several published reports, approximately half of childhood constipation occurs during the first year of life.

Clinical

History

• History is often helpful in discriminating functional constipation from Hirschsprung disease. Asking parents when their child passed his or her first bowel movement after birth is particularly important. Most children with Hirschsprung disease have difficulties with constipation dating to birth or shortly after birth. In most published series, more than one half of infants with Hirschsprung disease do not pass meconium during the first 36 hours of life and are diagnosed with constipation within the first 4-6 months of life.
• Asking the family about specific symptoms of their child's constipation is also important. Inquiring about the onset and duration of symptoms, whether the passage of bowel movements appears to be painful, and whether any bleeding has been associated with defecation is important. Obtaining history of fecal incontinence or soiling is also crucial because many parents confuse fecal soiling (ie, encopresis) with chronic or recurrent diarrhea.
• Most cases of chronic childhood constipation are precipitated by painful bowel movements with resultant voluntary withholding of stool.⁹ In young children, parents often confuse withholding of stool with pain or excessive straining (see Media file 5). In many cases of functional constipation, parents can identify a precipitating event.
• In young infants, functional constipation often develops at the time of a dietary transition (eg, from breast milk to formula, from formula to whole milk).
• In toddlers, functional constipation often develops near the time of toilet training.
• In toddlers and young children, constipation frequently develops following an illness associated with either a severe diaper dermatitis or dehydration.
• In older children, functional constipation often develops at the time of school entry because they refuse to defecate while they are at school.

Physical

• The most important part of the physical examination is the rectal examination. Perform a rectal examination in any child with chronic constipation, regardless of age. In young infants, the anus should be sufficiently large to permit the introduction of a pinkie finger.
• Carefully examine the perineum for any sacral dimples or pits that might indicate an abnormality of the distal spinal cord. Also note the location of the anus on the perineum.
  • In most children, the anus is approximately halfway between the posterior fourchette (base of the scrotum) and the tip of the coccyx.
  • Whether children with anterior displacement of the anus are at increased risk for constipation is not entirely clear. To date, no large prospective studies have been performed. In some cases, if the anus is sufficiently anterior, a posterior rectal shelf may develop, resulting in abnormal defecation dynamics. Some pediatric surgeons and pediatric gastroenterologists believe that this entity is at one end of the continuum of imperforate anus with a perineal fistula.
• Examine the anus for the presence of any fissures, fistulae, or hemorrhoids. Also, confirm the presence of an anal wink. To elicit an anal wink, stroke the perianal skin with a pin or probe. In response to the stroking, the subcutaneous portion of the external anal sphincter should contract and visibly pucker at the anal margin. Failure to elicit this reflex can indicate an abnormality with either peripheral sensory or motor nerves or central connections mediating the reflex.
• Upon digital examination, note the size of the anal canal, the size of the rectum, and whether any intrarectal masses are present. Also, note if the rectum is empty or filled with stool and note the consistency of the stool.
• Among children with Hirschsprung disease, the rectum is typically quite small and empty of stool. Following the digital examination, the infant may have a gush of liquid stool because the functional obstruction has transiently been relieved.
• Among children with functional constipation, the rectum is generally enlarged, and stool is present just beyond the anal verge.

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