Pediatric Constipation

Bowel motility is one of the most complex and sophisticated functions in the human body. The colon absorbs water and functions as a reservoir. Liquid waste delivered by the small bowel into the cecum becomes solid stool in the descending and sigmoid colon. The colon has a slow motility; its peristalsis seems to be less active in the distal portions of the colon. Every 24-48 hours, the rectosigmoid develops active peristaltic waves that indicate that it must be emptied. This is perceived by the individual, who then has the capacity to voluntarily retain the stool or to empty it, depending on social circumstances.

Most children suffering from constipation have no underlying medical condition. They are often labeled as having functional constipation or acquired or functional 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 distention ultimately results in both loss of rectal sensitivity, and loss of the urge to defecate, which can lead to fecal incontinence (ie, encopresis).

In the United States, constipation is extremely common among infants and young children. In a 1987 report, Issenman et al found that 16% of parents reported that their 2-year-old children had constipation[5] ; 2 decades later, Loening-Baucke reported that the prevalence of constipation was 22.6% among 482 children aged 4-17 years.[6] In a longitudinal study of children aged 9-11 years, Saps et al reported an 18% overall prevalence of constipation.[7]

In a European study, 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,[8] and a South American study by de Araujo Sant'Anna and Calcado found that 28% of Brazilian children aged 8-10 years were constipated.[9]

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.

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 than males.

It is very important to educate the family that using laxatives continuously for months may be necessary. This is particularly true in toddlers, because many months may pass before their association between the fear of pain and defecation is extinguished.

Caregivers should be reassured as to the safety of long-term laxative use, and the importance of persistent treatment should be strongly reinforced. Address the common misconceptions about laxative dependency and the increased risk of colon cancer due to long-term laxative usage.

Inform the family that relapses are common and are often associated with changes in the child's daily routine (eg, vacations) or during times of stress. Also, inform the family that the requirement of intermittent therapy with laxatives into adulthood is not unusual.

For patient education information, see Constipation in Children.

History is often helpful in discriminating functional constipation from Hirschsprung disease (see Differentials). 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.

Asking about a history of fecal incontinence or soiling is also important as many parents confuse fecal soiling (ie, encopresis) with poor hygiene or chronic or recurrent diarrhea.

Most cases of chronic childhood constipation are precipitated by painful bowel movements with withholding of stool.[10]  In very young children, withholding is reflexive and pain avoidant, whereas in older children the witholding may be more conscious but again is almost always a means of avoiding pain. In young children, parents often confuse withholding of stool with abdominal pain or excessive straining. In many cases of functional constipation, parents can identify a precipitating event. Common withholding behaviors are detailed in the image below.

This image delineates common withholding behaviors in young children.

In young infants, functional constipation often develops at the time of a dietary transition (eg, from breast milk to formula, the addition of solid foods into the diet, from formula to whole milk).

In toddlers, functional constipation often develops near the time of toilet training. In toddlers and young children, constipation may develop 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.

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, to exclude underlying anatomic abnormalities that might account for the constipation, such as an imperforate anus with perineal fistula, intestinal obstruction (mass effect), or Hirschsprung disease. In young infants, the anus should be sufficiently large to permit the introduction of a pinkie finger.

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.

Sacral dimples or pits

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 in boys; where the labia minora meet in girls) 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.

Anal fissures, fistulae, or hemorrhoids and anal wink reflex

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.

Constipation is recognized and diagnosed by most practitioners based on the child's clinical presentation (eg, a patient has difficulty passing stool or has not passed stool in 1-3 days). Laboratory studies are generally unnecessary unless an underlying condition is suspected to be the cause, in which case diagnostic tests should be obtained as appropriate.

In most cases, the most useful radiologic study for the evaluation of patients with bowel problems is plain abdominal radiography (see the following image). This helps the clinician determine how much stool is present in the colon. Overflow diarrhea is suggested if the child has a history of diarrhea and there is large fecal burden on the radiograph. An abdominal radiograph can also be useful in assessing the colonic fecal burden among children who are obese or who refuse a rectal examination. It can also be helpful in assessing the efficacy of medical therapy when the child's history is unclear.

Due to the high frequency of unnecessary abdominal radiographs for pediatric patients with constipation in the ED despite evidence-based guidelines that recommend against imaging,[11, 12] a study by Ferguson et decreased the rates of abdominal radiographs from 62% to 24% by the use of an interventional improvement project that included grand rounds on constipation and sharing best practices.[13, 14]

Plain abdominal radiograph that demonstrates stool throughout the colon.

Radiography can be useful in excluding or diagnosing Hirschsprung disease. Although the diagnosis of Hirschsprung disease ultimately relies on histologic demonstration of an absence of ganglion cells in the affected colon, the diagnosis is often suggested by single-contrast barium enema. The radiologist is looking for a change in colonic diameter from the narrow aganglionic segment to a more dilated ganglionic segment. This transition zone is characteristic of Hirschsprung disease and is shown in the image below.

This unprepared single-contrast barium enema demonstrates a transition zone consistent with Hirschsprung disease.

The image below illustrates megasigmoid and impacted stool, and thus, slow motility.

Contrast enema of a patient with megasigmoid and impacted stool.

Avoid air-contrast enemas and rectal manipulation

Do not use an air-contrast enema when looking for Hirschsprung disease, because radiographic evaluation of Hirschsprung disease depends on finding a change in colonic caliber between the normal and abnormal aganglionic segment. With an air-contrast study, the colon is evacuated prior to the study to identify mucosal abnormalities. By evacuating the colon before the study, any caliber change may be masked.

Moreover, do not perform any form of rectal manipulation on the child (eg, rectal examination, therapeutic enema, suppository) for 48 hours before the procedure. Rectal manipulation with suppositories or therapeutic enemas may transiently dilate the narrowed distal segment, causing a false negative result.

Although an unprepared barium enema has reasonably good diagnostic sensitivity and specificity in older children, this procedure is substantially less reliable during the first several months of life. The proximal colon may require several months after birth to dilate sufficiently for a transition zone to be apparent.

Anorectal manometry can be useful in discriminating between functional constipation and Hirschsprung disease. A balloon catheter is inserted into the rectum during this test. Normally, when the rectal balloon is inflated, the internal anal sphincter relaxes reflexively (anorectal reflex), as is shown in the image below.

The images illustrate normal anorectal manometry with relaxation of the internal anal sphincter in response to rectal distention.

Among patients with Hirschsprung disease, the internal anal sphincter fails to relax in response to rectal distention. As many as 20% of healthy children may have a falsely absent reflex, especially if they were born prematurely or with low birth weight; however, a positive response is strong evidence against Hirschsprung disease.

Rectal biopsy is the definitive means of establishing or excluding Hirschsprung disease.[15] This procedure is usually unnecessary when the clinical picture and the radiologic findings are characteristic of idiopathic constipation.

The tissue is examined histologically for the presence or absence of ganglion cells in the submucosal plexus. If the patient's rectum has no ganglion cells, the diagnosis of Hirschsprung disease is confirmed.

A study by Doniger et al sought to determine the performance of point-of-care ultrasound using a sonographic numeric cutoff value for diagnosing constipation. The study found that in children with abdominal pain, there was a strong correlation of an enlarged transrectal diameter with constipation.[16]

Although constipation is an extremely common problem among children, few studies have systematically evaluated different management strategies. Childhood constipation is treated in many ways, and virtually any therapeutic regimen is likely to be effective as long as it is sufficiently aggressive and persistent.[17] Because of the medical profession's understanding of the pathophysiology of the problem, the basic tenets of therapy include evacuation of the colon, elimination of pain with defecation, and establishing regular bowel habits.[18]

A group of patients with severe constipation that does not respond to conservative medical therapy may require more aggressive treatments, including surgery. A discussion of these interventions is beyond the scope of this article. See Surgery for Pediatric Constipation and Bowel Management.

Also see Constipation.

When there is evidence of a fecal impaction, initial therapy should be directed at evacuating the colon. A fecal impaction can be identified by palpating a hard mass of stool on physical examination, finding a large amount of stool in a dilated rectum during rectal examination, or finding excessive stool in the colon on an abdominal radiograph.

Aggressive use of oral cathartics such as polyethylene glycol, sodium phosphate, magnesium citrate, or a balanced electrolyte solution with polyethylene glycol or a series of enemas can accomplish disimpaction.[19] In trials, disimpaction by the oral route or the rectal route were reported to be equally effective.[20, 21]

Convincing a young child to ingest sufficient amounts of oral cathartics to evacuate their colon may be difficult; therefore, enemas or suppositories may be necessary. See the images below.

Position for enema administration in an infant.

Another position for enema administration.

Administration of an enema.

Incorrect enema administration. The enema is administered against stool impaction and cannot be successful.

Enema administration with a tube.

Enema with inflated Foley balloon catheter.

Administration of an enema against impacted stool.

Administration of an enema against fecal impaction.

Once the colon has been evacuated, chronic laxative therapy is generally required.[22] Virtually any laxative can be used as long as it is used in sufficient quantity to produce 1-2 soft stools daily. In young children, eliminating any pain associated with the passage of bowel movements is extremely important. Using very large doses of laxatives to produce very soft stools may be necessary.

Continuing laxative therapy for a number of months is often necessary. As a result, it is very important to reassure caregivers that long-term laxative usage is safe. Address the common misconceptions regarding laxative dependency, laxative abuse, and the risk of colon cancer due to long-term laxative usage.

If the child has anal fissures, using Xylocaine ointment or hydrocortisone suppositories for a short time period to provide symptomatic relief may be helpful.

In many cases, long-term success in the management of constipation depends on the child establishing regular and routine toilet times. It is generally recommended that the child be encouraged to attend the toilet twice daily for 5-10 minutes, preferably after breakfast and after supper to take advantage of the gastrocolic reflex. For school age children, it is preferable not to expect the child to attend the toilet while at school.

When the affected child has passed bowel movements regularly for weeks or months without apparent pain, fear, or excessive straining, it is reasonable to attempt to discontinue laxative therapy. Inform the family that relapses are common, particularly with changes in the child's daily routine (eg, vacations) and during times of stress. Also inform the family that requiring intermittent therapy with laxatives into adulthood is not unusual.

Dietary changes, such as increasing the child's intake of fluids and carbohydrates, are commonly recommended as part of the treatment of constipation.[23]

Balanced diet

Complex carbohydrates and unabsorbable sugars (eg, sorbitol) are found in many fruit juices (eg, prune, pear, apple). These carbohydrates increase stool frequency by increasing fecal water content. Although randomized controlled trials have not been conducted to examine the effects of increasing the intake of fluids, nonabsorbable carbohydrates, or fiber on childhood constipation, recommending a balanced diet that includes whole grains, fruits, vegetables, and an abundance of fluids seems appropriate. Because data are limited, forceful implementation of a particular diet does not seem warranted.

Cow milk avoidance

In infants and young children, it is appropriate to consider removing cow-milk protein from the diet for a period is appropriate, because chronic constipation may be precipitated by ingestion of cow-milk proteins. Iacono and colleagues found that among 27 Italian children aged 5-36 months who had chronic constipation, the constipation resolved in 78% of the children when soy milk was substituted for cow milk; in most cases, the constipation recurred when cow milk was reintroduced.[24]

Unnecessary or ineffective dietary changes

Switching the patient to a low-iron formula is not necessary. Several studies have shown that ingestion of iron-supplemented formulas is not associated with an increased incidence of constipation.[25]

Although some evidence suggests that gastrointestinal flora is important in gut motility, no evidence suggests that gut florae are different in children with constipation than gut florae in healthy controls. While both Lactobacillus and Bifidobacterium have been shown to increase stool frequency and decrease stool consistency in healthy adults, there is little evidence that probiotics are effective in treating constipation in either adults or children.[26, 27]  However, a study that investigated whether oral supplementation with Lactobacillus reuteri DSM 17938 during the first 3 months of life can reduce the onset of colic, gastroesophageal reflux, and constipation in term newborns reported that prophylactic use of L reuteri DSM 17938 during the first 3 months of life reduced the onset of functional gastrointestinal disorders and reduced private and public costs for the management of this condition.[28]

A meta-analysis by Wegh et al that included 52 randomized controlled trials evaluating nonpharmacologic treatments for constipation showed no benefit for the use of probiotics or synbiotics.[29]  Similarly, a Cochrane review found insufficient evidence to determine whether probiotics are effective in treating chronic functional constipation in children.[30]

Consultation with a pediatric gastroenterologist or pediatric surgeon is appropriate if the child's history or examination findings suggest an underlying organic cause (eg, Hirschsprung disease). Also seek consultation when the child fails routine therapy or when management is otherwise complex.

See Surgery for Pediatric Constipation and Bowel Management.

Assessment of constipation after disimpaction assures that the prescribed therapy was effective. At that time, maintenance laxative therapy can be prescribed. When the patient has bowel movements regularly for weeks or months without apparent pain, fear, or excessive straining, attempting to discontinue laxative therapy is reasonable.

A study by Sharifi-Rad et al that included 90 children reported treatment success with interferential electrical stimulation as an adjuvant therapy for functional constipation.[31]

In several randomized trials, laxatives have been shown to be beneficial in the treatment of chronic childhood constipation.[32, 33] Studies have also shown that polyethylene glycol,[34] mineral oil, magnesium hydroxide, and lactulose are effective and can be used for prolonged time periods without risk.

The key to pharmacotherapy is to use a sufficient amount of laxative to produce the desired effect. The intermittent use of stimulant laxatives may be necessary in some children; however, routine usage of these agents in young children is not generally recommended. Continuous laxative therapy may be required for a number of months until the association between pain and the passage of bowel movements has been extinguished.

Class Summary

Osmotic laxatives produce an osmotic effect in the colon that results in distention and promotes peristalsis.

Polyethylene glycol (MiraLAX, Dulcolax Balance)

Polyethylene glycol (PEG) is a long chain of ethylene glycol molecules that results in an extremely large molecule. This agent is very poorly absorbed and functions as an osmotic laxative. The powders are tasteless and odorless and dissolve completely in nearly all liquids including water.

These agents often can also be used as purgatives in preparation for colonoscopy. At very large dosages, PEG is occasionally difficult to take and its usage may be associated with nausea, bloating, abdominal cramps, and vomiting.

Magnesium hydroxide (Philips' Milk of Magnesia, Fleet Pedia-Lax)

Magnesium is a divalent cation that is maximally absorbed in the distal small intestine. At low concentrations, magnesium appears to be absorbed by a saturable carrier-mediated process influenced by vitamin D. At higher concentrations, magnesium absorption appears to occur largely by diffusion and is quite inefficient. Increased serum magnesium levels may release cholecystokinin, which stimulates gastrointestinal motility and secretion; this may explain why some children experience abdominal cramping.

Magnesium is mostly flavorless but has a thick, chalky texture. It is made more palatable when mixed with a fluid (eg, milk, chocolate milk).

Lactulose (Constulose, Enulose, Generlac, Kristalose)

Lactulose is a synthetic, nonabsorbable disaccharide that is available as a 70% solution. This agent is generally very well tolerated and tastes sweet. Lactulose formulation contains 10 g lactulose/15 mL of oral solution. Bloating, borborygmi, and flatulence are common side effects as a result of colonic flora fermenting the lactulose.

Sorbitol

Sorbitol is an alcohol of glucose that is largely nonabsorbable. This agent is available as a 70% solution. As with lactulose, sorbitol is generally well tolerated and tastes quite sweet. Bloating, borborygmi, and flatulence are common side effects as a result of colonic flora fermenting the sorbitol.

Magnesium citrate (Citroma)

Magnesium is a divalent cation that is maximally absorbed in the distal small intestine. At low concentrations, magnesium appears to be absorbed by a saturable carrier-mediated process influenced by vitamin D. At higher concentrations, magnesium absorption appears to occur largely by diffusion and is quite inefficient. Increased serum magnesium levels may release cholecystokinin, which stimulates gastrointestinal motility and secretion; this may explain why some children experience abdominal cramping.

Sodium acid phosphate (OsmoPrep, Visicol)

Phosphate is a divalent anion largely absorbed in the proximal small intestine. When this agent is administered as an enema, only small amounts are absorbed such that the phosphate functions as an osmotic agent. Each 15 mL contains 7.2 g monobasic sodium phosphate monohydrate and 2.7 g dibasic sodium phosphate heptahydrate.

Class Summary

Lubricating agents soften stools and decrease water absorption from the gastrointestinal tract. They may also promote salt and water secretion by the colon.

Mineral oil (Kondremul)

Mineral oil is a nonabsorbable fat that softens stool and decreases water absorption, partly by its metabolism in the colon to hydroxy fatty acids. This agent is largely tasteless and has an oily consistency that is made more palatable if it is cold or mixed into a fluid (eg, orange juice). When mineral oil is taken in high doses, many children experience seepage of orange oil into their underwear, which can produce perianal pruritus.

Class Summary

Stimulant laxatives increase peristaltic activity in the gastrointestinal tract. Most of these agents also stimulate salt and water secretion in the colon.

Senna (Ex-Lax, Senokot, Fletcher's, Little Tummys)

Sennosides are plant alkaloids that stimulate colonic salt and water secretion and promote colonic motility. At higher doses, these agents often produce abdominal cramping. Long-term use in animals has not been associated with any evidence of cathartic colon, tachyphylaxis, or secondary hyperaldosteronism.

Bisacodyl (Dulcolax, Bisco-Lax)

Bisacodyl is a colorless and odorless compound that is very poorly absorbed. This agent can be administered orally or rectally. Bisacodyl increases colonic peristalsis and stimulates salt and water secretion.

Class Summary

Stool softening agents allow incorporation of water and fat into the stool, causing the stool to soften.

Docusate sodium (Colace, Docu-Soft, Diocto, DSS)

Docusate sodium is used to avoid straining during defecation. This agent allows incorporation of water and fat into the stool, causing it to soften.

Class Summary

Emollient stool softeners cause stool to soften. Stimulants increase peristaltic activity in the gastrointestinal tract. Most of both these types of agents also promote salt and water secretion by the colon.

Senna concentrate/docusate (Peri-Colace, Senokot, Dok Plus)

Docusate sodium allows incorporation of water and fat into the stool, causing it to soften. Casanthranol is an anthraquinone stimulant hydrolyzed by colonic bacteria into an active compound. Action is usually produced 8-12 hours after administration of this combination.