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constipation in a young child as seen on x-ray

Image: Constipation in a young child as seen on X-ray. By: James Heilman. License: CC BY 3.0


Definition

The definition of constipation is based on variations in stool frequency, consistency, and the effort involved in passing stool.

In the United States, normal stool frequency ranges from 3 stools per day to 3 stools per week. Constipation is the infrequent passage of hard, dry stool. Symptoms that persist for more than 2 weeks are considered significant.

The Iowa criteria of constipation, which covers children at least 2 years of age, includes 2 or more of the following characteristics in the 8 weeks preceding examination:

  • Painful defecation
  • Fewer than 3 bowel movements per week
  • Large stools in the rectum felt via abdominal or digital rectal examination
  • History of large-sized stools that may obstruct the toilet
  • 2 or more episodes of fecal incontinence (encopresis) per week

Functional (voluntary) withholding is the most common cause of constipation.

Functional constipation, as defined by the ROME III classification, requires 2 or more of the following features in a child with developmental age ≥ 4 years and occurring for at least 3 months with onset at least 6 months before diagnosis (with insufficient criteria for a diagnosis of irritable bowel syndrome):

  • Straining in at least 25% of defecations
  • Lumpy or hard stools
  • Sensation of incomplete evacuation in at least 25% of defecations
  • Sensation of anorectal obstruction in at least 25% of defecations
  • Manual maneuvers required to facilitate at least 25% of defecations
  • Loose stools rarely present without laxatives

Non-retentive fecal soiling, a term originally coined for children soiling with no signs of fecal retention by PACCT (the Paris Consensus on Childhood Constipation Terminology Group) is defined as the “passage of stools in an inappropriate place, occurring in children with a mental age of 4 years or older, with no evidence of constipation on history or examination.”

Epidemiology

Childhood constipation is most commonly seen in toddlers around the time of toilet training. Positive family history is present in about 26%–48% of patients. Prevalence rates of constipation in patients of all ages range from 0.7%–29.6% worldwide.

Clinical Signs and Symptoms

Symptom Explanation
Stool-withholding maneuvers Often misinterpreted as straining; typical features include:

  • Infants: back arching
  • Older infants/toddlers: moving back and forth, straightening legs, tip-toeing
  • Older children: standing stiff or squat
Blood in stools Painful bleeding from the rectum in older children is associated with fissures, fistulae, and infection, and may be a sign of Crohn’s disease. Children with rectal polyps present with painless bleeding. In infancy, this is classically associated with cow-milk protein allergy.
Pain Pain is often an enigmatic constellation of clues rather than a single symptom. In pediatric constipation, pain should be assessed and categorized according to location, character, and timing. Pain can be present in the abdomen or near the anus.
Infrequent stools Reduced bowel movements are often synonymous with constipation and are a defining criterion. However, almost half of the pediatric population with constipation does not have a reduced frequency of passage of stools.
Soiling Although it is often mistaken as diarrhea, involuntary fecal soiling (encopresis) is associated with constipation in almost 90% of children.
Enuresis and other urinary disturbances Compression of the bladder by impacted stools in the rectum can simulate enuresis. Chronic pelvic muscular contraction often culminates in incomplete relaxation during voiding and post-void residues.
Associated issues Obesity, whether a direct correlation or a confounding factor, is often associated with constipation.

Etiopathogenesis

Constipation is often a symptom of a larger problem; other times, it is a diagnosis on its own. The pathogenesis varies depending on the cause, trigger, and circumstances around which a child develops constipation (see table below).

Situation Explanation
Difficult toilet training This is more common in children with physical, intellectual, or developmental disabilities. If a healthy child refuses to cooperate, they may be experimenting with autonomy and limit-testing. Behavioral therapy with positive reinforcement is recommended.
Febrile illness Decreased fluid intake after a fever often manifests as hard stools.
Secondary behavioral issues Though benign in nature, secondary behavioral issues such as not using the bathroom at school, running late to school in the morning, or withholding stool may mimic constipation.
Secondary constipation Constipation secondary to an organic cause is seen only in about 10% of children. Refractory constipation, family history, and associated symptoms may point toward diagnoses such as hypothyroidism or Hirschsprung’s disease.
Stool-withholding behavior Pain upon defecation in childhood may lead to reflex stool-withholding behavior, resulting in a vicious cycle of more hard stools and more pain. Adequate treatment of the original cause alleviates this behavior.

Diagnosis

Because constipation has a varied etiology, it is important to be cautious when distinguishing organic causes from functional ones, as the treatment differs accordingly.

A systematic approach with meticulous history taking, careful physical examination, and imaging is often successful. History should reveal any positive findings that will help classify constipation as per the type of etiology noted in the table above. A detailed history taking comprising the child’s bowel habits, toilet training, and stool habits in different environments (eg, at school and home) is a must.

Physical examination should include a review of the child’s growth parameters, abdominal examination, external examination of the perineum and perianal area, adigital examination of the anorectum, evaluation of the thyroid and spine, and a neurologic evaluation for appropriate reflexes (cremasteric, anal wink, patellar) according to the American Academy of Family Physicians.

A perineal examination is helpful in anorectal anomalies and perianal infections. Associated neurological, mental status, and other systems examinations should be carried out when necessary.

History and physical examination should decisively rule out any signs of organic causes, as noted in the table below.

History Examination Probable Diagnosis
Delayed passage of meconium Mouth ulcers, cough Cystic fibrosis
Weight loss Fever Chronic organic disease, inflammatory bowel disease
Failure to thrive, sensitivity to cold, fatigue Absent/brisk lower-limb reflexes Hypothyroidism, hypocalcemia
Abnormal bowel habits since birth Blood/mucus–mixed stools, perianal skin tags Crohn’s disease
Change of bowel movement after the introduction of cow’s milk Blood in stools Cow-milk allergy

Investigations

Constipation is mainly a clinical diagnosis. A few ancillary helpful tests include those outlined in the table below.

Test Explanation
Abdominal skiagram (X-ray) Assessment of colon and rectosigmoid area as per the Leech score of constipation is often helpful. The Leech score can range from 0 to 5 based on the amount of feces visible: 0 for no visible feces, 1 for scanty feces, 2 for mild fecal loading, 3 for moderate fecal loading, 4 for severe fecal loading, and 5 for severe fecal loading with bowel dilatation.
Abdominal ultrasonography (USG) The rectopelvic ratio is calculated using USG to visualize megarectum in children with constipation.
Anal manometry Often used in children with refractory symptoms and for planning surgical interventions
Initial blood screen Tests for hypothyroidism, markers of inflammation, nutritional assessment
Sweat testing, electrolytes Tests for cystic fibrosis, when indicated
Rectal biopsy Gold standard for diagnosis of Hirschsprung’s disease

Differential Diagnosis

The following differential diagnoses should be considered in a child with constipation:

Liquid stool may pass around the hard stool mass and thereby mimic the symptoms of diarrhea.

Treatment

Treatment consists of 2 phases: initial disimpaction, which is intended to relieve acute constipation, followed by maintenance therapy to avoid continued constipation and prevent recurrence.

Disimpaction

Acute relief of constipation by dislodging impacted stools is the first step in management. Disimpaction is typically performed over 2–5 days. Various measures utilized for disimpaction are summarized in the table below.

Mode of Treatment Explanation
Oral/nasogastric approach
  • Progressively increasing the oral dose of polyethylene glycol is often the first line of management.
  • Magnesium-containing preparations are avoided to prevent overdose and toxicity complications. Lactulose, sorbitol, senna, or bisacodyl laxative can also be used.
Rectal approach Saline and mineral oil enemas can be used. Phosphate preparations are best avoided in light of acute phosphate nephropathy secondary to such products.

Maintenance Therapy

Once disimpaction occurs, maintenance therapy is initiated to prolong the benefits of disimpaction and to prevent recurrence (see table below). The treatment typically takes about 3–12 months and is completed once a child’s bowel movements return to normal.

Mode of Treatment Explanation
Behavioral modification As functional constipation is the most common etiology of childhood constipation, behavioral therapy is the most important maintenance therapy. Proper toilet training, effective schooling, and positive reinforcement of good habits play an important part.
Education Learning, or re-learning, healthy bowel movement habits. It is recommended that the child sit on the toilet for 10–15 minutes daily at a regularly scheduled time, usually following a meal, in an attempt to have a bowel movement.
Diet Optimization of a child’s diet with fiber, adequate fluid intake, fruits, and vegetables is beneficial in the long run.
Laxatives While the chronic use of stool softeners is strongly discouraged, the use of medications at half of disimpaction dose is encouraged. Polyethylene glycol is often the first choice, followed by lactulose, senna, sorbitol, and other laxatives. Stimulant laxatives are best avoided.

Treatment for organic diseases depends on the cause. Surgical intervention is needed only after the failure of medical management.

Complications

Pediatric constipation is not a serious condition, although it makes children uncomfortable. However, untreated or chronic constipation can lead to the following complications:

  • Breaks in the skin surrounding the anus, which causes pain (anal fissures).
  • The rectum may protrude out of the anus (rectal prolapse).
  • The child will withhold stool because of pain. This results in impacted stool collecting in the colon and rectum before leaking out due to overflow (encopresis).

Pediatric Encopresis

Definition

Pediatric encopresis is the involuntary or intentional passage of feces in inappropriate situations after the age of 4 years (or equivalent developmental level).

Classification

Encopresis is classified as noted in the following table.

Type Explanation
Retentive With constipation and secondary overflow and leakage around obstruction; more common
Non-retentive Without constipation
Primary Seen in boys from infancy; often associated with global developmental delay and enuresis
Secondary Seen in children after successful toilet training; often functional in nature, marked by a higher level of stressors and psychological disorders

Encopresis is more common in boys than girls (4–6:1).

Etiology

Pediatric encopresis is caused mostly by constipation and emotional issues, including:

  • Premature, unplanned, difficult or conflicting toilet training
  • Alterations in a child’s schedule, including diet, starting school, and toilet training
  • Mental stressors, such as the birth of another child or parental divorce

Pathophysiology

In an overwhelming majority of cases, encopresis results from chronic constipation leading to overflow incontinence. Chronic constipation that results in incomplete evacuation of stools leads to continuous rectal distention as well as stretching of both the internal and external anal sphincter. Over time, a child gets used to chronic rectal distention, which makes them lose the ability to sense the normal urge to defecate. Fecal soiling results from soft or liquid stool leaking around the retained fecal mass.

Clinical Features

A child with encopresis may present with the following signs and symptoms:

  • Stool or liquid stool, which may leak and be mistaken for diarrhea
  • Abdominal pain
  • Loss or lack of appetite
  • The passing of large stools that block or almost block the toilet
  • Avoidance of bowel movements
  • Prolonged intervals between bowel movements
  • Constipation with dry, hard stools
  • Daytime wetting or bedwetting (enuresis)
  • Recurrent bladder infections, especially in girls

Diagnosis

The table below outlines the diagnostic assessment of pediatric encopresis.

Diagnostic Assessment Explanation
Points on history Meticulous history taking often reveals dissociated psychosocial functioning of the child, which leads to encopresis. Other relevant facts such as toilet training, abuse, and toileting at school may also be uncovered.
Points on examination Presence of fecal retention is a clear sign of chronic constipation. Negative rectal exam necessitates imaging tests such as X-ray.
Investigations X-ray reveals the level of fecal impaction, megacolon, and intestinal pseudo-obstruction.
Electromyography studies Abnormal sphincter physiology reflects poor prognosis.

Treatment

Encopresis, though benign, is often an embarrassing diagnosis for a child and therefore alleviating anxiety is an important part of treatment. Treatment addresses constipation first and then any underlying psychosocial stressors. The strategy can be summarized as outlined in the following table.

Treatment Modality Explanation
Address constipation All measures used in the disimpaction phase of constipation can also be used for acute relief. Short-term use of laxatives is preferred
Psychotherapy Concomitant behavioral modification, reinforcement of good toileting habits, the encouragement of regular bowel movements, and improved parental education, counseling, and understanding are the basis of psychotherapeutic support.
Diet High-fiber balanced diet with optimal fluid intake is recommended.
Gastroenterologist reference Though seldom indicated, referral to gastroenterology in the presence of megacolon and other signs of an underlying organic disease is indicated.
Medications Although tricyclic antidepressants are sometimes used, the evidence remains equivocal. Exacerbation of symptoms points to a limited role for antidepressants in retentive encopresis.

Prognosis

Regression of encopresis is common, irrespective of the treatment modality used. Treatment is often indicated when this occurs, as regression is associated with long-lasting psychological effects on children.

Summary

Childhood constipation is a common yet upsetting complaint. It is often a symptom, rather than a diagnosis, however. Functional constipation is the most common cause of constipation. Infrequent defecation, pain, soiling, stool-withholding, and enuresis are the most common symptoms.

Meticulous history taking, physical examination, and supplementary diagnostic tests can help secure a diagnosis. “Red flag” signs may indicate an underlying serious organic disease. Treatment of chronic constipation is divided into 2 phases: acute disimpaction, for immediate relief of constipation, followed by a maintenance phase to avoid relapses.

Laxatives, diet modification, education, and counseling, and behavioral therapy are instrumental in the treatment of pediatric constipation. Pediatric encopresis is the inappropriate passage of feces in children above the age of 4 years, or equivalent developmental age. It is more common in boys and is classified into primary/secondary and retentive/non-retentive categories.

Psychosocial stressors are often associated with encopresis. Consequently, behavioral therapy to ameliorate stressors plays a significant role. Encopresis usually resolves in most patients, irrespective of the treatment modality used.

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