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Constipation in Children: A Merck Manual of Patient Symptoms podcast

Constipation is responsible for up to 5% of pediatric office visits. It is defined as delay or difficulty in the passing of hard, sometimes large stools for ≥ 2 wk.

The frequency of normal bowel movements varies for infants. In the first year, the average number of bowel movements ranges from 2 to 4/day. This number also varies depending on whether infants are breastfed or formula-fed (breastfed infants have more frequent bowel movements). In general, signs of effort (eg, straining) do not signify constipation; infants only gradually develop the muscles to assist a bowel movement. After age 1 yr, children average 1 bowel movement/day.

Etiology

Constipation in children is divided into 2 main types:

• Organic (5%)
• Functional (95%)

Organic: Organic causes involve specific structural, neurologic, toxic/metabolic, or intestinal disorders. They are rare but important to recognize (see Table 15: Approach to the Care of Normal Infants and Children: Organic Causes of Constipation in Infants and Children).

The most common cause is

• Hirschsprung's disease

Other organic causes that may manifest in the neonatal period or later include

• Anorectal malformations
• Cystic fibrosis
• Metabolic disorders (eg, hypothyroidism, hypercalcemia, hyperkalemia)
• Spinal cord abnormalities

Functional: Functional constipation is difficulty passing stools for reasons other than organic causes.

In infants, the use of formula can lead to small, hard stools.

In older children, diets low in fiber and high in dairy lead to hard stools that are uncomfortable to pass and can cause anal fissures. Children sometimes put off having bowel movements because they have discomfort caused by fissures or because they do not want to interrupt play. To avoid having a bowel movement, children may tighten the external sphincter muscles, pushing the stool higher in the rectal vault. If this behavior is repeated, the rectum stretches to accommodate the retained stool. The urge to defecate is then decreased, and the stool becomes harder, leading to a vicious circle of painful defecation and worsened constipation. Occasionally, soft stool passes around the impacted stool and leads to stool incontinence.

Stress, toilet training, desire for control, and sexual abuse are also some of the functional causes of stool retention and subsequent constipation.

Table 15
Organic Causes of Constipation in Infants and Children Cause Suggestive Findings Diagnostic Approach Anatomic Anal stenosis Delayed passage of stool in the first 24–48 h of life Explosive and painful stools Abdominal distention Abnormal appearance or position of the anus Tight anal canal detected by digital examination Clinical evaluation Anteriorly placed anus Anal opening not located in the center of the pigmented area of the perineum (> 2 SD from the API norm) Calculation of API* indicating anterior placement, which varies by sex: Girls: < 0.29 Boys: < 0.49 Imperforate anus Abdominal distention No passage of stool Blind rectal pouch detected during examination Clinical examination Endocrine or metabolic disorders Diabetes insipidus Polydipsia Polyuria Excessive crying quieted with water intake Weight loss, vomiting Urine and serum osmolality ADH levels Hypercalcemia Nausea, vomiting Muscle weakness Abdominal pain Anorexia, weight loss Polydipsia Polyuria Serum Ca Hypokalemia Muscular weakness Polyuria, dehydration History of growth failure Possibly history of aminoglycoside, penicillin, or amphotericin use Electrolyte panel Hypothyroidism Poor feeding Bradycardia Large fontanelles and hypotonia in neonates Cold intolerance, dry skin, fatigue, prolonged jaundice Thyroid-stimulating hormone (TSH) Thyroxine (T4) Spinal cord defects Myelomeningocele Grossly visible lesion in vertebral spine at birth Decrease in lower-extremity reflexes or muscular tone Absence of anal wink Plain x-rays of lumbosacral spine Spinal MRI Occult spina bifida Sacral hair tuft or pit Spinal MRI Tethered cord Change in gait Pain or weakness in lower extremities Urinary incontinence Back pain Spinal MRI Intestinal disorders Celiac sprue Failure to thrive Recurrent abdominal pain Diarrhea after wheat is introduced into the diet IgA and IgG antigliadin antibodies IgA antiendomysium antibodies IgA antitissue glutaminase Cystic fibrosis Delayed passage of meconium Poor weight gain Repeated episodes of pneumonia Sweat test Consideration of genetic testing for confirmation Hirschsprung's disease Delayed passage of meconium Abdominal distention Tight anal canal detected by digital examination Barium enema Anorectal manometry and rectal biopsy for confirmation Irritable bowel syndrome Chronic abdominal pain Intermittent diarrhea and constipation Feeling of incomplete evacuation Passage of mucus Clinical evaluation Pseudo-obstruction Nausea, vomiting Abdominal pain and distention Abdominal x-ray Tumor Weight loss Night sweats, fever MRI Drug adverse effects Use of anticholinergics, antidepressants, chemotherapeutics, or opioids Suggestive history Clinical evaluation Toxins Infant botulism New onset of poor suck Hypotonia History of ingestion of honey before age 12 mo Test for botulinum toxin in stool Lead toxicity Most likely asymptomatic Possible intermittent abdominal pain, fatigue, irritability Loss of developmental milestones Blood lead level *API (anal position index) is calculated as follows: Girls: Distance from anus to fourchette/distance from coccyx to fourchette (normal mean ± SD 0.45 ± 0.08) Boys: Distance from anus to scrotum/distance from coccyx to scrotum (normal mean ± SD 0.54 ± 0.07) SD = standard deviation.

Evaluation

Evaluation should focus on differentiating functional constipation from constipation with an organic cause.

History: History of present illness in neonates should determine whether meconium has been passed at all and, if so, when. For older infants and children, history should note onset and duration of constipation, frequency and consistency of stools, and timing of symptoms—whether they began after a specific event, such as introduction of certain foods or a stressor that could lead to stool retention (eg, introduction of toilet training). Important associated symptoms include soiling (stool incontinence), discomfort during defecation, and blood on or in the stool. The composition of the diet, especially the amount of fluids and fiber, should be noted.

Review of systems should ask about symptoms that suggest an organic cause, including new onset of poor suck, hypotonia, and ingestion of honey before age 12 mo (infantile botulism); cold intolerance, dry skin, fatigue, hypotonia, prolonged neonatal hyperbilirubinemia, urinary frequency, and excessive thirst (endocrinopathies); change in gait, pain or weakness in lower extremities, and urinary incontinence (spinal cord defects); night sweats, fever, and weight loss (cancer); and vomiting, abdominal pain, poor growth, intermittent diarrhea, and constipation (intestinal disorders).

Past medical history should ask about known disorders that can cause constipation, including cystic fibrosis and celiac sprue. Exposure to constipating drugs or lead paint dust should be noted. Clinicians should ask about delayed passage of meconium within the first 24 to 48 h of life, as well as previous episodes of constipation and family history of constipation.

Physical examination: The physical examination begins with general assessment of the child's level of comfort or distress and overall appearance (including skin and hair condition). Height and weight should be measured and plotted on growth charts.

Examination should focus on the abdomen and anus and on the neurologic examination.

The abdomen is inspected for distention, auscultated for bowel sounds, and palpated for masses and tenderness. The anus is inspected for a fissure (taking care not to spread the buttocks so forcefully as to cause one). A digital rectal examination is done gently to check stool consistency and to obtain a sample for occult blood testing. Rectal examination should note the tightness of the rectal opening and presence or absence of stool in the rectal vault. Examination includes placement of the anus and presence of any hair tuft or pit superior to the sacrum.

In infants, neurologic examination focuses on tone and muscle strength. In older children, the focus is on gait, deep tendon reflexes, and signs of weakness in the lower extremities.

Interpretation of findings: A primary finding that suggests an organic cause in neonates is constipation from birth; those who have had a normal bowel movement are unlikely to have a significant structural disorder.

In older children, clues to an organic cause include constitutional symptoms (particularly weight loss, fever, or vomiting), poor growth (decreasing percentile on growth charts), an overall ill appearance, and any focal abnormalities detected during examination (see Table 15: Approach to the Care of Normal Infants and Children: Organic Causes of Constipation in Infants and Children). A well-appearing child who has no other complaints besides constipation, who is not on any constipating drugs, and who has a normal examination likely has a functional disorder.

A distended rectum filled with stool or the presence of an anal fissure is consistent with functional constipation in an otherwise normal child. Constipation that began after starting a constipating drug or that coincides with a dietary change can be attributed to that drug or food. Foods that are known to be constipating include dairy (eg, milk, cheese, yogurt) and starches and processed foods that do not contain fiber. However, if constipation complaints begin after ingestion of wheat, celiac sprue should be considered. History of a new stress (eg, a new sibling) or other potential causes of stool retention behavior, with normal physical findings, support a functional etiology.

Red flags: The following findings are of particular concern:

• Delayed passage of meconium (> 24 to 48 h after birth)
• Hypotonia and poor suck (suggesting infant botulism)
• Abnormal gait and deep tendon reflexes (suggesting spinal cord involvement)

Testing: For patients whose histories are consistent with functional constipation, no tests are needed unless there is no response to conventional treatment. An abdominal x-ray should be done if patients have been unresponsive to treatment or an organic cause is suspected. Tests for organic causes should be done based on the history and physical examination (see Table 15: Approach to the Care of Normal Infants and Children: Organic Causes of Constipation in Infants and Children):

• Barium enema, rectal manometry, and biopsy (Hirschsprung's disease)
• Plain x-rays of lumbosacral spine; MRI considered (tethered spinal cord or tumor)
• Thyroid-stimulating hormone and thyroxine (hypothyroidism)
• Blood lead level (lead poisoning)
• Stool for botulinum toxin (infant botulism)
• Sweat test and genetic testing (cystic fibrosis)
• Ca and electrolytes (metabolic derangement)
• IgA and IgG antigliadin antibodies, IgA antiendomysium antibodies, IgA antitissue glutaminase (celiac disease)

Treatment

Specific organic causes should be treated.

Functional constipation is ideally initially treated with

• Dietary changes
• Behavior modification

Dietary changes include adding prune juice to formula for infants, increasing fruits and vegetables for older infants and children, increasing water intake, and decreasing the amount of constipating foods (eg, milk, cheese).

Behavior modification for older children involves encouraging regular stool passage after meals if they are toilet trained and providing a reinforcement chart and encouragement to them. For children who are in the process of toilet training, it is sometimes worthwhile to give them a break from training until the constipation concern has passed.

Unresponsive constipation is treated by disimpacting the bowel and maintaining a regular diet and stool routine. Disimpaction can occur through oral or rectal agents. Oral agents require consumption of large volumes of liquid. Rectal agents can feel invasive and can be difficult to give. Both methods can be done by parents under medical supervision; however, disimpaction sometimes requires hospitalization if outpatient management is unsuccessful. Usually, infants do not require extreme measures, but if intervention is required, a glycerin suppository is typically adequate. For maintenance of healthy bowels, some children may require OTC dietary fiber supplements. These supplements require consuming 32 to 64 oz of water/day to be effective (see Table 16: Approach to the Care of Normal Infants and Children: Treatment of Constipation).

Table 16
Treatment of Constipation Type of Therapy Agent Dose Selected Adverse Effects Disimpaction Oral Oral high-dose mineral oil (should not be used in neurologically impaired children in case of aspiration) 15–20 mL/yr of age (maximum 240 mL/day) for 3 days or until stool appears Fecal incontinence, malabsorption of fat-soluble vitamins (if treatments are repeated) Oral polyethylene glycol–electrolyte solution 25 mL/kg/h (maximum 1000 mL/h) by NGT until stool appears or 20 mL/kg/h for 4 h/day Nausea, vomiting, cramping, bloating Oral polyethylene glycol without electrolytes 1–1.5 g/kg dissolved in 10 mL/kg water once/day for 3 days Fecal incontinence Rectal Glycerin suppositories Infants and older children: ½–1 suppository once/day for 3 days or until stool appears None Rectal mineral oil enema 2–11 yr: 2.25 oz once/day for 3 days or until stool appears ≥ 12 yr: 4.5 oz once/day for 3 days or until stool appears Fecal incontinence, mechanical trauma Rectal phosphate Na enema 2– 4 yr: 1.13 oz once/day for 3 days or until stool appears 5–11 yr: 2.25 oz once/day for 3 days or until stool appears ≥ 12 yr: 4.5 oz once/day for 3 days or until stool appears Mechanical trauma, hyperphosphatemia Maintenance agents Oral osmotic and lubricant laxatives LactuloseSome Trade Names CEPHULAC CHRONULAC KRISTALOSE Click for Drug Monograph 1 mL/kg once/day or bid (maximum 60 mL/day) Abdominal cramping, flatus Mg hydroxide 1–2 mL/kg once/day If overdose, risk of hypermagnesemia, hypophosphatemia, or secondary hypocalcemia Mineral oil 1–3 mL/kg once/day Fecal incontinence Polyethylene glycol 3350 powder (in 8 oz of water) 1–18 mo: 2.5–5 mL (0.5–1 tsp) once/day > 18 mo–3 yr: 10–15 mL (2–3 tsp) once/day ≥ 3 yr: 10–20 mL (2–4 tsp) once/day Fecal incontinence Sorbitol (syrup, 70% solution) 1–11 yr: 1 mL/kg once/day or bid ≥ 12 yr: 15–30 mL once/day or bid Abdominal cramping, flatus Oral stimulant laxatives (to be used for a limited period of time) BisacodylSome Trade Names DULCOLAX Click for Drug Monograph (5 mg tablets) 2–11 yr: 1–2 tablets once/day ≥ 12 yr: 1–3 tablets once/day Fecal incontinence, hypokalemia, abdominal cramps SennaSome Trade Names EX-LAX SENOKOT Click for Drug Monograph syrup: 8.8 mg sennosides/5 mL SennaSome Trade Names EX-LAX SENOKOT Click for Drug Monograph tablets: 8.6 mg sennosides/tablet > 1 yr: 1.25 mL once/day up to 2.25 mL bid 2–5 yr: 2.5 mL once/day up to 3.75 mL bid 6–11 yr: 5 mL once/day up to 7.5 mL bid ≥ 12 yr: 1 tablet once/day up to 2 tablets bid Abdominal cramping, melanosis coli Maintenance diet supplements Dietary fiber supplements Methylcellulose < 6 yr: 3.5–7.5 mL (¼–½ tbsp) once/day 6–11 yr: 7.5 mL (½ tbsp) once/day ≥ 12 yr: 15 mL (1 rounded tbsp) in 8 oz water 1–3 times/day Less bloating than other fiber supplements Psyllium 5–15 mL (1 tsp–1 tbsp [depending on concentration and formulation]) in 8 oz water 6–11 yr: once/day ≥ 12 yr: 1–3 times/day Bloating, flatus Sorbitol-containing fruit juices (eg, prune, pear, apple) Infants and older children: 1–4 oz/day Flatus

Key Points

• Functional constipation accounts for about 95% of cases.
• Organic causes are rare but need to be considered.
• Delayed passage of meconium for > 24 to 48 h after birth raises suspicion of structural disorders, especially Hirschsprung's disease.
• Early intervention with dietary and behavior changes can successfully treat functional constipation.

Last full review/revision February 2010 by Eve R. Colson, MD; Rachel L. Chapman, MD; Melissa R. Held, MD

Content last modified February 2010