Constipation and fecal incontinence represent common problems in children. Beyond the neonatal period, only a minority of children have an organic cause for their constipation and the etiology remains not well understood. Constipation rarely leads to life-threatening complications, but can cause emotional and physical distress and concerns for children and their families, ultimately impairing health-related quality of life. The hallmarks of constipation are infrequent painful defecation and fecal incontinence often accompanied by abdominal pain. In less than 15% of cases, children have fecal incontinence without a history and physical examination that indicates underlying constipation. These latter children are classified as functional nonretentive fecal incontinence (FNRFI) according to the Rome III criteria.
The aims of this chapter are to describe functional defecation disorders in children: functional constipation associated with or without fecal incontinence and FNRFI; to discuss the diagnostic approach and treatment regimens; and to report on treatment outcomes.
Definitions
Normal Stooling Pattern
Stool frequency changes in children with age. The stool frequency gradually declines from more than four stools per day during the first week of life to one to two stools per day by the age of 4 years. Differences in stooling frequency have been observed between healthy breast-fed and formula-fed infants. In the first 3 months of life, breast-fed infants have more frequent, softer, and more yellow-colored stools than standard formula-fed infants. The type of feeding does not influence the stooling quantity. From 5 years of age, the majority of children pass stools daily or every other day without straining or withholding.
Constipation
For many years, physicians, patients, and parents have used different definitions for constipation. The Rome II criteria, developed in 1999, attempted to provide a symptom-based definition of functional constipation, mostly based on expert opinion. Such criteria were subsequently found to be too restrictive and were revised, between 2004 and 2006, in the Rome III version of pediatric functional gastrointestinal disorders. Different studies have shown that the Rome III criteria are far less restrictive than the Rome II criteria in diagnosing functional defecation disorders. Burgers et al. retrospectively evaluated patients referred for functional defecation disorders, comparing the Rome II and Rome III criteria. They demonstrated that by using the Rome III criteria, functional constipation is diagnosed more frequently compared with the Rome II criteria (87% and 34%, respectively). To fulfill the new Rome III criteria for functional constipation, children should have two or more of symptoms described in Box 11-1 . The Rome III Committee suggested different diagnostic criteria for constipation in infants and toddlers up to 4 years of age and for childhood constipation in older children and adolescents.
Diagnostic criteria must include:
- •
Two or more criteria for at least 1 month in infants up to 4 years
- •
Two or more symptoms for at least once per week for at least 2 months in children at least 4 years
- 1.
Two or fewer defecations per week
- 2.
At least one episode of fecal incontinence per week
- 3.
History of retentive posturing or excessive stool retention
- 4.
History of painful or hard bowel movements
- 5.
Presence of a large fecal mass in the rectum
- 6.
History of large-diameter stool that may obstruct the toilet
- 7.
Additional criteria: without fulfilling irritable bowel syndrome criteria
- 1.
Fecal Incontinence
Fecal incontinence is defined as the involuntary loss of stool into the underwear in a child older than the age of 4 years. It represents an upsetting and psychologically distressing problem in children. Functional fecal incontinence can be divided into constipation-associated fecal incontinence or “overflow” incontinence, and functional nonretentive fecal incontinence (FNRFI). More than 80% of the children with functional fecal incontinence have retentive fecal incontinence. These findings were also observed in a Sri Lankan epidemiologic survey showing that indeed retentive fecal incontinence is 4.5 times more common than FNRFI.
Functional fecal incontinence in children can also be subclassified as either primary, in those children who have never been toilet trained, and secondary, in those in which the incontinence returns after successful toilet training.
It is important to differentiate between retentive and nonretentive fecal incontinence because these two conditions differ in etiology and management. The diagnostic criteria for FNRFI according to the Rome III criteria are listed in Box 11-2 .
Diagnostic criteria must include all of the following in children at least 4 years of age, for at least 2 months prior to diagnosis
- 1.
Defecation into places inappropriate to the social context at least once per month
- 2.
No evidence of an inflammatory, anatomic, metabolic, or neoplastic process that explains the symptoms
- 3.
No evidence of fecal retention
Epidemiology
Constipation
Constipation is a common symptom in children, accounting for 3% to 10% of general pediatric outpatient visits and up to 25% of visits to pediatric gastroenterologists worldwide. The worldwide prevalence varies from 0.7% to 29.6%. The lack of consensus in diagnostic criteria and differences in cultural ideas about normal bowel habits may have contributed to the worldwide variation of the prevalence in the literature.
Loening-Baucke showed that the prevalence rate for constipation in the first year of life was 3%, and 10% during the second year of life, with 97% having functional constipation. Two studies from Brazil showed even higher rates (>20%) of constipation in a population of 1- to 10-year-olds. Similar prevalence data are reported in Asia: the prevalence of constipation in Taiwan was 32.2% in children in elementary schools and in Hong Kong 12% to 28%. Similarly, developing nations in Asia, such as Sri Lanka, also show that 15% of the school children have chronic constipation.
Fecal Incontinence
The worldwide prevalence of fecal incontinence is estimated between 0.8% and 7.8%. A 4% prevalence rate for functional fecal incontinence was found in a retrospective review in 482 children, 4 to 17 years of age, attending a primary care clinic in the United States. In this study, fecal incontinence was related to constipation in 95% of the children. Similarly, studies from Asia report prevalence data in Iran, South Korea, and Sri Lanka, ranging from 2% to 7.8%.
Fecal incontinence is more common in boys, with a male-to-female ratio ranging from 3:1 to 6:1. There is a negative correlation between the prevalence of functional incontinence and age. It is more common in younger children (prevalence 4.1% in children ranging from 5 to 6 years of age and 1.6% in 11- to 12-year-olds). Similar, a Sri Lankan study including children age 10 to 16 years reported a lower prevalence (<1%) in children aged 16 years compared to children aged 10 years (5.4%). The majority of children with functional fecal incontinence seek medical care at the age of 7 to 8 years.
Pathogenesis
Constipation
The pathophysiology of constipation in children is multifactorial and remains incompletely understood. In a fraction of patients, constipation is secondary to a known organic disorder. In more than 90% of children presenting with constipation, no obvious organic cause is found and thus it is classified as functional.
Constipation may occur at any age, but children appear most vulnerable in one of three phases: (1) infancy, with the introduction of cereals and other solids and weaning of (breast) milk; (2) toddlers, at the time of toilet training; and (3) older children, who avoid bathrooms at school.
Constipation in the newborn and in early infancy is a special situation because of the possibility of a congenital disorder. If meconium passage is delayed for more than 24 hours, several diseases need to be considered, including Hirschsprung’s disease (HD) and anatomic defects of the spinal cord or anorectal malformations. A meconium plug may cause neonatal constipation and may be associated with either HD or cystic fibrosis. Table 11-1 depicts the organic causes of constipation.
| Intestinal causes | Hirschsprung’s disease |
| Anorectal malformation | |
| Neuronal intestinal dysplasia | |
| Neuropathic conditions | Spinal cord abnormalities |
| Spinal cord trauma | |
| Neurofibromatosis | |
| Static encephalopathy | |
| Tethered cord | |
| Metabolic, endocrine causes | Hypothyroidism |
| Diabetes mellitus | |
| Hypercalcemia | |
| Hypokalemia | |
| Vitamin D intoxication | |
| Drugs | Opioids |
| Anticholinergics | |
| Antidepressants | |
| Other causes | Anorexia nervosa |
| Sexual abuse | |
| Scleroderma | |
| Cystic fibrosis | |
| Dietary protein allergy |
In the majority of children, constipation results from purposeful or subconscious stool withholding after the passage of a hard, painful, or frightening bowel movement. Fear of defecation leads to withholding of stool, called retentive posturing. Instead of relaxing the pelvic floor for defecation, the retentive infant will contract the pelvic floor and gluteal muscles in an attempt to avoid defecation. Children often stiffen their legs, grunt, or rise on their toes and rock back and forth. In many cases, this behavior is misinterpreted by parents as an extreme effort to pass stool. Loening-Baucke reports that 45% of the constipated infants and toddlers exhibited stool-withholding behavior. A child may also refuse defecation as part of a control and independence struggle with parents during toilet training. A significant number of school-aged children refuse to use school toilets, often citing poorly maintained and unhygienic facilities. As a consequence of withholding, whatever the cause is, the rectal mucosa absorbs water from the fecal mass and the retained stools become progressively more difficult to evacuate. This process leads to a vicious circle of stool retention. When stool retention remains untreated for a long period, the rectal wall becomes stretched and a megarectum develops. This can result in overflow fecal incontinence, loss of rectal sensation and, ultimately, loss of normal urge to defecate.
Young infants with constipation should be differentiated from those with infant dyschezia. Infant dyschezia, according to the Rome III criteria, is defined as straining and crying for at least 10 minutes before successful passage of soft stools without any other health problem, in an infant younger than 6 months of age. Infant dyschezia differs from constipation in that the stools are not hard when passed. A recent Dutch study shows that the prevalence of infant dyschezia, according to the Rome III criteria, at 1 and 3 months of age is low (3.9% and 0.9%, respectively) and declines with age. Only 6.6% of infants with dyschezia developed constipation. Symptoms of infant dyschezia improve and resolve without intervention in most cases. Parents need to be reassured that this phenomenon is part of the child’s learning process and that interventions, like laxatives, are unnecessary.
Little consensus exists in the pediatric literature regarding risk factors for childhood constipation, although genetic predisposition, nutritional factors (low consumption of fiber, fruit, and vegetables; cow’s milk protein allergy), obesity, physical inactivity, living in war affected areas, and low socioeconomic and educational levels have been suggested to contribute to the development of childhood constipation. Psychological factors, such as being bullied at school, sexual and physical abuse, and in particular anxiety and depression, are considered predisposing to constipation. In addition, constipation has been reported more frequently in children with specific behavioral phenotypes, such as autism spectrum disorders and obesity. A recent study showed that children with attention-deficit/hyperactivity disorder (ADHD) had an increased prevalence of constipation (4.1% vs. 1.5%) and fecal incontinence (0.9% vs. 0.15%) compared to healthy children.
No association has been found between development of early constipation and the timing, style, or techniques used for toilet trainings.
Fecal Incontinence
Functional fecal incontinence is caused by either retentive (constipation associated) or functional nonretentive fecal incontinence. Other causes of fecal incontinence are listed in Table 11-2 .
| Functional causes | Functional constipation associated fecal incontinence |
| Functional nonretentive fecal incontinence (FNRFI) | |
| Organic causes | Repaired anorectal malformation |
| Postsurgical Hirschsprung’s disease | |
| Spinal dysraphism | |
| Spinal cord trauma | |
| Spinal cord tumor | |
| Cerebral palsy | |
| Myopathies affecting the pelvic floor and external anal sphincter |
In otherwise healthy children, fecal incontinence is secondary to “overflow,” and therefore results from the presence of constipation. Stool withholding creates a vicious circle of progressive accumulation of feces and hardening of the fecal mass. Finally, feces seep between the fecal mass and rectal wall, and escape through the anal canal when the sphincter muscles are relaxed. The volume of stools that leaks out is small and most of the time just stains the underwear. Incontinence of feces can occur both during the day and at night. Nocturnal incontinence is considered to be an indicator of severe accumulation of feces in the rectum.
On the other hand, children with FNRFI pass stools into inappropriate places without evidence of stool retention. The majority of them have complete evacuation of bowel, not just staining of the underwear as in retentive incontinence. The pathophysiology of FNRFI is still unclear. In patients with FNRFI, colonic transit times, rectal compliance, and sensitivity thresholds (as measured by rectal barostat) were normal.
Fecal incontinence is a stressful symptom for both patients and their families. Parents may believe that the child can be blamed for fecal incontinence and should therefore be punished for accidents. Parental misconceptions about the causes of fecal incontinence could lead to a treatment delay. A recent study assessing parental knowledge about fecal incontinence demonstrated that seeking professional medical care could decrease parental misconceptions and increase understanding and helping of the child.
Risk factors for functional fecal incontinence are low socioeconomic background, unhygienic toilets, living in an urban area or war-affected zone, hospitalization of the child for another illness, and bullying at school. Analysis of the child behavior checklist showed that approximately one-third of children with FNRFI had psychological disturbances and behavioral problems. Psychological and behavioral abnormalities such as aggressive behavior, social withdrawal, anxiety, depression, disruptive and oppositional behavior, and poor school and social performances were frequently noted in children with functional fecal incontinence.
Quality of Life
Although constipation is not a life-threatening condition, it can cause emotional and physical distress for the affected child and family. Multiple studies showed that constipation can result in impaired health-related quality of life (HRQoL). In the United States, children with constipation had lower mean self-reported HRQoL scores than healthy controls and children with inflammatory bowel disease and gastroesophageal reflux disease. Parents of constipated children reported lower perceived emotional and social scores for their children compared to parents of healthy children. Similar observations have been described in Australia and Brazil; constipation negatively affected both physical and psychological HRQoL scores. A recent study from China showed that functional constipation had a significant impact on HRQoL of constipated children and their families, as well as their family function. A cross-sectional survey in Sri Lanka found that children with constipation had lower HRQoL in all four main domains (physical, social, emotional, and school functioning); significantly higher somatization scores in affected children and significant negative correlation between HRQoL and scores were obtained for somatization and severity of symptoms. Fecal incontinence even more negatively affects the quality of life of these children and their families. Children with incontinence were found to have higher rates of psychosocial problems compared to children without. Furthermore, when constipation continues into adulthood, affected individuals report difficulties with social contact and intimacy of up to 20%. It is important to address these issues during clinical evaluation to understand the impact of constipation on the lives of affected children.
Clinical Evaluation and Diagnosis
The clinical presentation of constipation in children is obvious in the majority but may be subtle and nonspecific in a subset of children. The physician should be aware of symptoms and signs of organic causes or red flag symptoms, as described earlier. It is important to emphasize that constipation and fecal incontinence are clinical diagnoses that are primarily based on symptoms in the absence of red flag symptoms, and therefore in the majority of patients no further testing is needed.
History
The medical history should include questions about the time of the first bowel movement after birth. It is well known that more than 99% of term newborns pass meconium in the first 48 hours of life. Because maturation of the intestinal motor function is delayed in preterm infants, they consequently may have a delay in the passage of the first stool. In addition, failure to pass the meconium within the first 24 hours of life raises the suspicion for HD.
Other important questions include the age of onset; frequency, consistency, and size of stools; whether the child experiences pain during defecation or exhibits retentive posturing; and whether blood is present on the toilet paper. Large caliber stools, which may be large enough to clog the toilet, may cause anal fissures, commonly manifested as blood on the toilet paper. Information about the incontinence frequency and day and/or nighttime soiling must be obtained. Fecal incontinence can be mistaken for diarrhea by some parents. An assessment of the stool pattern, using a defecation diary in combination with the Amsterdam infant stool scale (AISS; Figure 11-1 ) or Bristol stool scale (BSS), can be used to estimate the severity of constipation. The AISS is developed for use in infants and children who are not yet toilet trained. In the AISS, the stool consistency, the amount, and color of stools are described. The BSS, on the other hand, is not age specific and only describes stool consistency. Consequently, the AISS is better adapted for children defecating in diapers and should therefore be used in preference to the BSS in this patient group.
Gathering information about stool form can be challenging because parents may not directly observe all stools. The child could describe his/her stools by using the modified Bristol Stool Form Scale for Children (mBSFS-C; Figure 11-2 ). In the mBSFS-C, the original BSS is adapted by decreasing the number of stool categories from seven to five.
Physicians should ask about the presence of abdominal pain or distension, loss of appetite, fever, nausea, vomiting, weight loss or poor weight gain, problems with neuromuscular development, and psychological or behavioral problems. Furthermore, urinary incontinence and urinary tract infections are reported in a considerable number of children with constipation. Dietary history and the history of previous treatment strategies for constipation should be investigated. Finally, it is essential to ask about important life events that might contribute to the development of retentive behavior such as death in family, birth of a sibling, school problems, and sexual abuse.
Physical Examination
A thorough physical examination should be performed in all children and should start with measurement of weight and height. Obesity is a clear predisposing factor for developing chronic constipation, and metabolic or endocrine disorders may lead to short stature and growth restriction. Abdominal examination provides valuable information concerning the accumulation of gas or feces. Palpable fecal masses are present in 50% of children with chronic constipation. Evaluation of the perianal region provides valuable information about the position of the anus, evidence of fecal incontinence, skin irritation, eczema, fissures, hemorrhoids, and signs of possible sexual abuse. The anorectal digital examination assesses the perianal sensation, anal tone, size of the rectum, and the contraction and relaxation of the anal sphincter. The lumbosacral area should be inspected for the presence of a sacral dimple, a tuft of hair, or asymmetry of the buttocks, which may indicate spina bifida occulta.
Laboratory Investigations
The European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) formulated in their recommendations that routine laboratory testing to screen for hypothyroidism, celiac disease, and hypercalcemia is not recommended in children with constipation in the absence of alarm symptoms.
These recommendations are in line with a recent study showing that only a minority of the children with constipation who undergo routine laboratory testing are diagnosed with a new organic disease. Only 1.7% was diagnosed with celiac disease, only 0.6% with hypothyroidism, and none with hypercalcemia. The likelihood of finding an organic cause decreases even further in children who present with constipation as their only symptom.
Evidence is conflicting for allergy testing to diagnose cow’s milk protein (CMP) allergy in children with functional constipation. Two studies reported that 68% to 78% of children affected by constipation and CMP allergy improved after CMP elimination diet. Both studies were performed in an allergy center, which could have led to an overestimation of the prevalence of this association. More importantly, the authors did not use the double-blind provocation test that is considered the gold standard method for diagnosing allergy to a food antigen. A subsequent prospective study conducted in Italy in 91 patients affected by chronic constipation did not confirm this association. Still, a 2- to 4-week trial of avoidance of CMP might be indicated in a child with intractable constipation.
Radiologic Investigations
Diagnostic tests are frequently used to diagnose childhood constipation. Nevertheless, a systematic review evaluating the additional value of diagnostic tools in the diagnosis of functional constipation in children found insufficient evidence for abdominal radiography, including colonic transit time (CTT) measurement and abdominal ultrasound.
Abdominal Radiography
The sensitivity and specificity of abdominal radiography in diagnosing childhood constipation range from 60% to 80% and from 43% to 90%, respectively. On the basis of currently available evidence, the National Institute for Health and Care Excellence guideline and the new ESPGHAN/NASPGHAN constipation guidelines concluded that abdominal radiography should not be recommended as an additional test for constipation in children, and therefore has no role in the diagnosis of functional constipation. Radiography is useful only for determining the presence of a fecal rectal mass when there is uncertainty as to whether the patient is constipated and rectal examination is not possible because of obesity, refusal, or psychological factors (sexual abuse) that make a rectal examination too traumatic.
Colonic Transit Time
One of the underlying mechanisms of idiopathic constipation is thought to be a disturbance of intestinal motility. Consequently, CTT is assumed to be decreased in children with idiopathic constipation in comparison to healthy children. CTT can be measured with the following noninvasive techniques: radiopaque sitz (plastic) markers ( Figure 11-3 ), scintigraphy (transit of radioisotopes; Figure 11-4 ), and tracking the movement of a pressure, pH, temperature capsule (wireless motility capsule, WMC). Three different patterns of CTT can be described on colonic transit studies. These include normal colonic transit, colonic inertia (also known as slow-transit constipation with slow propagation throughout all colonic segments), and outlet obstruction (delay is mainly in the rectosigmoidal region). Outlet obstruction is the most commonly encountered form in pediatric functional constipation. However, a CTT study is not recommended for diagnosing constipation, and may only be useful for discriminating between functional constipation and FNRFI and in situations in which the diagnosis is not clear.
Furthermore, it is important to emphasize that CTT may be normal in up to 50% of children with constipation and in 90% of the children with FNRFI. De Lorijn et al. showed that a bowel diary is sufficient to diagnose constipation. A low defecation frequency and/or a high fecal incontinence frequency recorded with a bowel diary correlated with total CTT measured with radiopaque markers.
Ultrasonography
Abdominal Ultrasonography
Based on the assumption that fecal retention is one of the main features of constipation, assessment of stool retention and size of rectum and colon are measured using abdominal ultrasonography. A rectal diameter larger than 30 mm is considered as enlarged, and some studies have demonstrated that the diameter of the rectum is significantly larger among constipated children compared to healthy children. Although this test is considered to be a simple, noninvasive technique to demonstrate fecal retention, there is insufficient evidence that the transverse diameter can be used as a predictor of constipation and fecal impaction. On the other hand, transabdominal ultrasound has been shown to be a reliable alternative to assess the rectal filling state, and might replace digital rectal examination in the evaluation of fearful children with constipation.
Contrast Enema
Contrast enema is a radiologic technique using contrast to visualize the anal canal and rectum. This technique is useful in identifying anatomic abnormalities but is unnecessary in uncomplicated constipation. A contrast enema is often used in the diagnostic work-up of HD, in which a transition zone between aganglionic and ganglionic bowel may be observed. However, a systematic review showed that a contrast enema had the lowest sensitivity compared with rectal suction biopsy and anorectal manometry (70% vs. 93% and 91%, respectively), leading to false-negative results. Rectal suction biopsy is the most accurate test in the diagnostic work-up of patients suspected of having HD.
Manometry
Anorectal Manometry
Anorectal manometry measures pressures in the anorectal region and provides a way to quantify the function of the internal and external anal sphincters. Anorectal manometry is only indicated to demonstrate the presence of the rectoanal inhibitory reflex, which is absent in children with anal achalasia or in children with HD. When the rectoanal inhibitory reflex is absent, the diagnosis of HD must be confirmed by histochemical evaluation of the rectum.
Anorectal manometry can be useful in differentiating between constipation-associated fecal incontinence and FNRFI. It has been shown that children with constipation-associated fecal incontinence have higher thresholds for rectal sensation than those with FNRFI.
Colonic Manometry
Colonic manometry is a diagnostic test performed only in specialized motility centers to differentiate between normal colonic motor function and colonic neuromuscular disorders in the evaluation of children with intractable constipation. Colonic manometry may be useful in children with longstanding and intractable constipation if a gastrointestinal motility disorder is suspected. This test is used in clinical practice in children with severe constipation when medical therapy fails to identify children who may benefit from surgery, such as the creation of an antegrade continence enema. In this select patient group, colonic manometry leads to recommendations to change therapy (mostly to surgery) in 93% of patients.
Magnetic Resonance Imaging
To date, evidence does not support the use of magnetic resonance imaging (MRI) of the spine in patients with intractable constipation without other neurologic abnormalities. A recent study involving children with defecation disorders (constipation, constipation-associated fecal incontinence, and FNRFI) reported spinal cord abnormalities (such as an intradural lipoma or tethered cord) in only 3% of affected children. Imaging of the spinal cord is therefore recommended only in children presenting with neurologic complaints or physical symptoms, such as gluteal cleft deviation, suggestive of spinal cord abnormalities. Rosen et al. reported improvement in constipation after the spinal cord abnormalities were surgically corrected.
Treatment for Constipation
The lack of randomized controlled studies in children has made the treatment of constipation largely based on clinical experience rather than on evidence-based controlled clinical trials. Acute constipation is traditionally treated with a high fiber diet and sufficient fluid intake, filling out a bowel diary, and toilet training. However, a recently published systematic review reported that evidence does not support the use of either fiber supplements or an increase in fluid intake, but instead suggested oral laxatives in the treatment of functional constipation. The recently published ESPGHAN/NASPGHAN guidelines includes four important phases in the treatment of chronic constipation: (1) education, (2) disimpaction, (3) prevention of reaccumulation of feces, and (4) follow-up Figure 11-5 .
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