Constipation is responsible for up to 5% of pediatric office visits. It is defined as delay or difficulty in defecation.
Normal frequency and consistency of stool varies with children's age, and diet; there is also considerable variation from child to child.
Most (90%) normal neonates pass meconium within the first 24 hours of life. During the first week of life, infants pass an average of 4 to 8 stools/day; breastfed infants typically have more stools than formula-fed infants. During the first few months of life, breastfed infants pass a mean of 3 stools/day, versus about 2 stools/day for formula-fed infants. By age 2 years, the number of bowel movements decreases to slightly < 2/day. After age 4 years, it is slightly > 1/day.
In general, signs of effort (eg, straining) in a young infant do not signify constipation. Infants only gradually develop the muscles to assist a bowel movement.
Etiology
Constipation in children is divided into 2 main types:
Organic
Organic causes of constipation involve specific structural, neurologic, toxic/metabolic, or intestinal disorders. They are rare but important to recognize (see Table: Organic Causes of Constipation in Infants and Children).
The most common organic cause is
Other organic causes that may manifest in the neonatal period or later include
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Anorectal malformations
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Metabolic disorders (eg, hypothyroidism, hypercalcemia, hyperkalemia)
Functional
Functional constipation is difficulty passing stools for reasons other than organic causes.
Children are prone to develop functional constipation during 3 periods:
Each of these milestones has the potential to convert defecation into an unpleasant experience.
Children may put off having bowel movements because the stools are hard and uncomfortable to pass 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 (encopresis).
In older children, diets low in fiber and high in dairy may lead to hard stools that are uncomfortable to pass and can cause anal fissures. Anal fissures cause pain with stool passage, leading to a similar vicious circle of delayed bowel movements, resulting in harder stool that is more painful to pass.
Stress, desire for control, and sexual abuse are also some of the functional causes of stool retention and subsequent constipation.
Organic Causes of Constipation in Infants and Children
Cause |
Suggestive Findings |
Diagnostic Approach |
Anatomic |
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Anal stenosis |
Delayed passage of stool in the first 24–48 hours of life Explosive and painful stools Abdominal distention Abnormal appearance or position of the anus Tight anal canal detected by digital examination |
Clinical evaluation |
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Anteriorly displaced anus |
Severe chronic constipation with marked straining and pain when stool is passed Typically no response to aggressive use of stool softeners and cathartics Anal opening not located in the center of the pigmented area of the perineum |
Calculation of anal position index* indicating anterior placement, which varies by sex: |
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Abdominal distention No passage of stool Abnormal appearance or position of the anus or possibly no anus |
Clinical examination |
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Endocrine or metabolic disorders |
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Polydipsia Polyuria Excessive crying quieted with water intake Weight loss Vomiting |
Urine and serum osmolality Antidiuretic hormone levels Serum sodium Sometimes water deprivation test |
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Nausea, vomiting Muscle weakness Abdominal pain Anorexia, weight loss Polydipsia Polyuria |
Serum calcium |
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Muscular weakness Polyuria, dehydration History of growth failure Possibly history of aminoglycoside, diuretics, cisplatin, or amphotericin use |
Electrolyte panel |
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Poor feeding Bradycardia Large fontanelles and hypotonia in neonates Cold intolerance, dry skin, fatigue, prolonged jaundice |
Thyroid-stimulating hormone (TSH) Thyroxine (T4) |
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Spinal cord defects |
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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 |
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Possibly sacral hair tuft or pit |
Spinal MRI |
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Tethered cord |
Change in gait Pain or weakness in lower extremities Urinary incontinence Back pain |
Spinal MRI |
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Spinal cord tumor or infection |
Back pain Pain or weakness in lower extremities Decrease in lower-extremity reflexes Change in gait Urinary incontinence |
Spinal MRI |
Intestinal disorders |
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Celiac disease (gluten enteropathy) |
Symptom onset after introduction of wheat into diet (typically after age 4–6 months) Failure to thrive Recurrent abdominal pain Bloating Diarrhea or constipation |
Complete blood count Serologic screening for celiac disease (IgA antibody to tissue transglutaminase) Endoscopy for duodenal biopsy |
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Cow's milk protein intolerance (milk protein allergy) |
Vomiting Diarrhea or constipation Hematochezia Anal fissures Failure to thrive |
Symptom resolution with elimination of cow's milk protein Sometimes endoscopy or colonoscopy |
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Delayed passage of meconium or meconium ileus in the neonate Possible repeated episodes of small-bowel obstruction (meconium ileus equivalent) in older children Failure to thrive Repeated episodes of pneumonia or wheezing |
Sweat test Genetic testing |
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Delayed passage of meconium Abdominal distention Tight anal canal detected by digital examination |
Barium enema Anorectal manometry and rectal biopsy for confirmation |
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Chronic recurrent abdominal pain Often alternating diarrhea and constipation Feeling of incomplete evacuation Passage of mucus No anorexia or weight loss |
Clinical evaluation |
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Intestinal pseudo-obstruction |
Nausea, vomiting Abdominal pain and distention |
Abdominal x-ray Colonic transit time Antroduodenal manometry |
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Intestinal tumor |
Weight loss Night sweats Fever Abdominal pain and/or distention Palpable abdominal mass Bowel obstruction |
MRI |
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Cerebral palsy and other severe neurologic deficits |
In most children with cerebral palsy, which causes intestinal hypotonia and motor paralysis Tube feedings with low-fiber formulas |
Clinical evaluation |
Drug adverse effects |
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Use of anticholinergics, antidepressants, chemotherapeutics, or opioids |
Suggestive history |
Clinical evaluation |
Toxins |
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New onset of poor suck, feeding difficulties, anorexia, drooling Weak cry Irritability Ptosis Descending or global hypotonia and weakness Possible history of ingestion of honey before age 12 months |
Test for botulinum toxin in stool |
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Most likely asymptomatic Possible intermittent abdominal pain, sporadic vomiting, fatigue, irritability Loss of developmental milestones |
Blood lead level |
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* Anal position index (API) is calculated as follows: |
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SD = standard deviation. |
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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 months (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, and intermittent diarrhea (intestinal disorders).
Past medical history should ask about known disorders that can cause constipation, including cystic fibrosis and celiac disease. 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 hours 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.
Red flags
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: Organic Causes of Constipation in Infants and Children). A well-appearing child who has no other complaints besides constipation, who is not taking 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 disease 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.
Testing
For patients whose histories are consistent with functional constipation, no tests are needed unless there is no response to conventional treatment of constipation. 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: Organic Causes of Constipation in Infants and Children):
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Barium enema, rectal manometry, and biopsy (Hirschsprung disease)
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Plain x-rays of lumbosacral spine; MRI considered (tethered spinal cord or tumor)
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Thyroid-stimulating hormone and thyroxine (hypothyroidism)
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Blood lead level (lead poisoning)
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Stool for botulinum toxin (infant botulism)
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Sweat test and genetic testing (cystic fibrosis)
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Calcium and other electrolytes (metabolic derangement)
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Serologic screening usually for IgA antibodies to tissue transglutaminase (celiac disease)
Treatment
Specific organic causes of constipation should be treated.
Functional constipation is ideally initially treated with
Dietary changes include adding prune juice to formula for infants; increasing fruits, vegetables, and other sources of fiber 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 over-the-counter dietary fiber supplements. These supplements require consuming 32 to 64 oz of water/day to be effective (see Table: Treatment of Constipation).
Treatment of Constipation
Key Points
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Functional constipation accounts for about 95% of cases.
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Organic causes are rare but need to be considered.
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Delayed passage of meconium for > 24 to 48 hours after birth raises suspicion of structural disorders, especially Hirschsprung disease.
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Early intervention with dietary and behavior changes can successfully treat functional constipation.
