Abstract

This article addresses the diagnosis and treatment of pediatric fecal incontinence in 4 main categories:

(1) Functional fecal retention, the withholding of feces because of fear of painful defecation, results in constipation and overflow soiling. Treatment includes dietary changes, use of laxatives, and cognitive and behavioral interventions such as toilet training, which diminishes phobia and provides positive reinforcement through a rewards system.

(2) For functional nonretentive fecal soiling (encopresis), antidiarrheal agents can increase the consistency of stools and facilitate continence. Anorectal biofeedback for children has been proposed, but its efficacy remains unproven. Parents should be educated to conduct nonaccusatory toilet training and help children alleviate guilt and enhance self-esteem. Appropriately constructed trials are necessary to gauge the effect of adding prolonged use of enemas to an intensive toilet training program.

(3) Surgery can correct minor congenital anorectal anomalies by identifying the external sphincter, separating the rectum from the genitourinary tract, and reconstructing the anus. However, there is great variation in postsurgical functional outcomes for anorectal malformations. Double-blinded, randomized controlled trials could help define the role of appendicostomy, cecostomy, sphincter reconstruction, colostomy, and artificial sphincters.

(4) Children with spina bifida and fecal incontinence may benefit from techniques that teach them how to defecate. A continent appendicostomy (Malone procedure) is a promising treatment that completely cleanses the colon, increases the child’s autonomy, and decreases the chance of soiling. A cecostomy can be performed surgically, endoscopically, or radiologically to provide some of the same benefits.

In children, the term fecal incontinence encompasses both encopresis and soiling, the important difference being the quantity of feces lost. However, in the medical literature, these 2 terms are often used interchangeably. The most widely accepted definition for encopresis is the repeated expulsion of a normal bowel movement, whether involuntary or intentional, in inappropriate places (e.g., in clothing, on the floor) by a child aged 4 years or older (or equivalent developmental level). Soiling is defined as the involuntary leakage of small amounts of stool, resulting in staining of the underwear.

Fecal incontinence represents one of the most embarrassing and psychologically devastating problems of childhood. It is associated with low self-esteem, depression, and anger. Shame and fear of punishment often lead these children to deny the problem by lying to their parents and hiding soiled clothes. The prevalence of this condition has been estimated to be approximately 1% to 2% in otherwise healthy school age children.

Four main groups of children present with fecal incontinence: (1) children who have functional fecal retention with overflow soiling, (2) children with functional nonretentive fecal soiling, (3) children with anorectal malformations, and (4) children with spinal problems. There is also a much smaller group with miscellaneous causes of anal sphincter damage and dysfunction. The pathophysiologic mechanisms for fecal incontinence differ for each group, and different treatment strategies are needed for each of them.

Functional fecal retention with overflow soiling

Functional fecal retention, the most common chronic defecation disorder in children, is the withholding of feces because of fear of painful defecation. This condition is responsible for up to 25% of visits to pediatric gastroenterologists and 3% to 5% of visits to general pediatricians. Typically, it develops at the time of toilet training or when the child starts school. Functional fecal retention is most likely the result of long-standing stool retention in the rectum. The increasing difficulty in passing the excessively firm stools leads to stool-withholding behavior. When the child experiences an urge to defecate, he or she assumes an erect posture and stiffly holds the legs together to forcefully contract the pelvic and gluteal muscles. Consequently, the rectum accommodates to its contents and the urge to defecate disappears. The retained stools become progressively more difficult to evacuate as a result of prolonged absorption of water, leading to a vicious cycle in which the rectum is increasingly distended by abnormally firm and large fecal contents. Once dilated, the rectum loses its sensory and motor function,  and the child develops an increased threshold for the urge to defecate. The constantly filled rectum leads to overflow soiling whenever the child tries to expel gas or the muscles used to withhold the rectal contents become fatigued. Children with severe constipation may experience encopresis/soiling at any time during the day; it may occur during the night in children who have extreme fecal impaction. Urinary incontinence may also occur because of the fecal mass exerting pressure on the bladder, and urinary tract infections secondary to frequent soiling are also quite common.

Colonic manometry can often identify a pattern of low-amplitude, simultaneous contractions in the dilated distal colon, despite normal motility in the proximal colon. The dilated portion of the colon is not able to generate effective, propagated contractions. An evaluation of anorectal function may reveal a very high threshold for the urge to defecate. Some children are not able to recognize the urge to defecate until a rectal balloon is filled with more than 300 mL of air, a value 10 times higher than normal. The decreased awareness of the presence of feces in the rectum leads to infrequent attempts at defecation and facilitates soiling.

Despite the relatively high prevalence of childhood constipation, large, randomized controlled therapeutic trials have not been conducted to assess this condition. The treatment of constipation, therefore, has been experiential rather than evidence based and consists of education, dietary modifications (increasing fiber and fluid intake), and use of laxatives. Often the medical management of these children is combined with behavioral techniques (toilet training combined with a rewards system, diminishment of toilet phobia), cognitive exercises (psychotherapy, cognitive therapy, and family therapy), or educational interventions. The aim of this combined therapeutic approach is to lower the level of physical and emotional distress associated with defecation, develop or restore normal bowel habits by positive reinforcement, preserve self-respect, and encourage the child and parents to take an active role during the treatment.

Biofeedback training may involve habit training, based on reinforcement and derived from psychologic learning theory, and uses instrument-assisted exercises designed to improve physiologic control. Biofeedback has been proposed for children with constipation and/or encopresis to enhance rectal sensation, strengthen and improve control of the external anal sphincter, and better coordinate muscle contraction and relaxation to achieve continence and effective defecation. In more than half the children with constipation and/or encopresis, the anal sphincter complex contracts instead of relaxing during simulated defecation in the laboratory. Biofeedback can help to normalize this phenomenon. However, normalization does not predict successful clinical outcome. The use of biofeedback training did not improve the sensation of urge and did not lead to superior outcomes compared with medical therapy only in fecally incontinent children. Thus, the role of biofeedback training in the treatment of defecation disorders in children is unproven.

Medical treatment usually lasts for several months and is successful in approximately 70% of children. Unfortunately, in severe cases in which chronic rectal dilatation has reached a “point of no return,” medical treatments will not be successful.

Research priority for functional fecal retention with overflow soiling

Conduct double-blinded, randomized controlled trials to compare the safety and efficacy of different laxative regimens, with large samples and long-term follow-up of children with mild and severe constipation.

Functional nonretentive fecal soiling

A subset of patients (male to female ratio of 4:1) lacks a history of functional fecal retention and instead has voluntary or involuntary evacuation of fairly large bowel movements in their underwear. According to the Rome II criteria, children older than age 4 years who present with this symptom at least once a week are considered to have functional nonretentive fecal soiling (FNRFS). Children with FNRFS often have daily bowel movements in the toilet and have a nearly complete stool evacuation in their underwear more than once a week. They have no palpable abdominal or rectal fecal mass on physical examination nor is a fecal mass identified on abdominal x-rays. Radiopaque markers of these children indicate that they have normal colonic transit times. The frequency of daytime and nighttime enuresis is higher (40% to 45%) for children with FNRFS compared with constipated children.

Historically, this form of soiling has been considered a manifestation of an emotional disturbance in school-aged children, representing an impulsive action triggered by unconscious anger. However, studies evaluating psychologic factors in children with encopresis have not observed serious psychologic disorders, and treatment with psychotherapy alone is often disappointing. Abnormalities in colonic sensory or motor function may also be present.

Treatment for FNRFS should use a multimodal protocol that includes parental education about the different aspects of encopresis, with an explicit effort to alleviate guilt and to use nonaccusatory toilet training. The child should try to defecate for 5 minutes after each meal; a daily diary and a rewards system are useful. The ultimate goal is to convince the child that it is critically important to use the toilet on a regular basis and to maximize the child’s ability to go to the bathroom immediately upon feeling the urge to defecate. Laxatives have been found to worsen outcome. Opioid agonists may be helpful. Involvement of a mental health professional can be very beneficial. Intensive treatment resolves the symptom in only 30% of children after 2 years and in 70% after 4 years. Incontinence persists into young adulthood in 22% of this population.

Research priority for functional nonretentive fecal soiling

Conduct a large, randomized controlled trial in which the additional effect of a prolonged enema program is compared with an intensive toilet training program. It is hypothesized that enemas administered on a regular basis may keep the rectum empty and minimize fecal losses during the day.
Anorectal malformations

Anorectal anomalies are congenital defects that occur once in 3000 to 5000 live births and are more common in boys. They can range from minor defects that require simple surgery to complex lesions requiring a high degree of skill and technical expertise to correct. These anomalies may be attributed to defective development of the lower rectum, urogenital tract, and anus in utero.

Pathophysiology

These anomalies can be divided into 3 main categories, based on the relationship of the rectum to the puborectalis muscle. High anomalies are frequently associated with fistulas to the urinary tract or vagina, with the rectum ending above the puborectalis muscle. Usually, there is no perineal opening. Intermediate anomalies occur at the level of or just below the puborectalis muscle, have connections to the genitourinary tract, and are often displaced anteriorly. In low anomalies, the rectum has descended below the level of the puborectalis muscle, and, usually, there are no fistulas into the genitourinary tract. The relationship to the puborectalis muscle has significant anatomic, physiologic, and surgical implications because the puborectalis muscle plays a critical role in achieving continence.

Patients with severe anorectal malformations generally present within 72 hours of birth with signs and symptoms of intestinal obstruction. Careful physical examination of the perineum is crucial. The presence of a midline groove with 2 well-formed buttocks and an anal dimple suggests a low anomaly. On the other hand, a flat bottom without a midline groove and absence of an anal dimple is characteristic of infants with high defects. Patients with obvious fistulas discharge meconium from the perineum, scrotum, vagina, or urethra. Infants with imperforate anal membrane, or covered anus, present during the neonatal period when they fail to pass meconium. In rectal atresia, the child is born with an externally normal appearing anus but with an obstruction located 1 cm to 2 cm above the mucocutaneous junction of the anus.

In girls, the most common anorectal defect is rectovestibular fistula, in which the rectum opens into the vestibule of the female genitalia. In boys, the most common defect is rectourethral bulbar fistula, in which the rectum communicates with the posterior urethra through a fistula that may be located in the lower posterior urethra (bulbar fistula) or in the upper posterior urethra (prostatic fistula). The highest congenital defects are high rectovaginal fistulas in girls and rectobladderneck fistulas in boys. These conditions are commonly associated with urologic abnormalities. Fortunately, they account for less than 10% of children with anorectal malformations. Cloaca, by far the most complex defect seen in female patients, is a condition in which the rectum, vagina, and urethra are fused together into a single common channel that opens into a single orifice in the perineum.

When an infant is suspected of having anorectal anomalies, other congenital defects should be sought. The higher and more complex the anorectal defect, the greater the chance that it will be life threatening. Urologic and spinal defects are the most common. Another group of patients will have gastrointestinal defects, including esophageal and duodenal atresia. Careful evaluations should be performed specifically to detect possible VATER (vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, radial and renal dysplasia) and VACTERL (additional cardiac and limb anomalies) associations.

Diagnosis and management of anorectal anomalies

In the first hours of life, infants with anorectal anomalies should undergo a careful evaluation to exclude other associated anomalies. A cardiac echogram should be performed to look for possible heart defects. An ultrasound of the abdomen and pelvis can be used to diagnose hydronephrosis, megaureter, and hydrocolpos. If these tests are negative, no further urologic studies are needed. If a high anorectal anomaly is suspected on a physical exam, imaging studies of the lower spine are indicated to rule out a tethered cord. The presence of severe sacral defects is considered the most important negative prognostic factor for achieving fecal continence.

Studies to classify anorectal malformations should be delayed 18 to 24 hours to allow bowel gas to reach the most distal portion of the rectum. The diagnostic workup should include a prone cross-table lateral radiograph and an invertogram, a procedure in which infants are held upside down for up to 5 minutes with their legs at 90-degree angles to the trunk and a radiopaque marker fixed to the usual location of the anus in an attempt to identify the level of obstruction. Water-soluble contrast studies through the bladder, vagina, urethra, and perineal fistula are useful to establish the anatomy. Magnetic resonance imaging studies can help define the anorectal anomaly in relation to the puborectalis muscle.

Major advances in pediatric surgery in recent decades have allowed for better anatomic reconstruction of these anomalies and have produced improved functional outcomes. The goal of surgery is to identify the external sphincter, separate the rectum from the genitourinary tract, and reconstruct the anus within the limits of the sphincter. Anorectal defects are treated with a protective colostomy before being repaired in the neonatal period. The exception is simple perineal fistula, whereby the rectum opens into the perineum anterior to the center of the sphincter with no associated defects and is treated by simple anoplasty. The main technical contribution in this treatment area has been posterior sagittal anorectoplasty, which has made it possible to repair complex anorectal malformations under direct vision. However, it is not yet completely proven that this technique improves long-term outcome.

In rectal atresia, the sphincter muscles and the sacrum are normal, and associated defects are rare. Patients with rectovestibular fistula (low defect) achieve voluntary bowel control in most cases, despite the frequent persistence of constipation. Patients with rectourethral bulbar fistula achieve long-term bowel control up to 90% of the time. In cloaca, the most important prognostic factor is the length of the common channel; a length of less than 3 cm is associated with voluntary bowel control in up to 80% of patients. Patients with channels greater than 3 cm in length are treated with both a laparotomy and posterior sagittal approach. More than 60% of these patients develop complications such as vesicouretheral reflux and obstructive uropathy. After these children reach the age of 3 months, they can undergo other operations to place the rectum, vagina, and urethra in their proper anatomical locations.

There is great variation in functional results after repair of different anorectal malformations (Table 1),  and a wide variety of long-term outcomes have been reported in the literature. There may be bias in published results because the largest published studies are usually from the most experienced surgical centers. Outcomes are often derived from interviewing parents, who may feel uncomfortable reporting suboptimal outcomes to the surgeon. There may also be a tendency to ignore or downplay moderate continence defects in children who were much sicker at birth.

Table 1. Long-Term Outcomes of Anorectal Malformation Repairs

NOTE. Adapted with permission from Youssef and Di Lorenzo. Data compiled from Rintala,  Pena and Hong,  and Rintala et al.

Generally, patients with low malformations have reasonably good functional outcomes. However, fecal incontinence, constipation, inability to control flatus, and/or sexual dysfunction occur in up to 30% of all patients born with low defects. Up to 85% of adults born with high anorectal malformations report social disability related to incontinence. In one study,  fecally incontinent children reported having problems with peer relations (17%), high rate of school absence (18%), and significant dietary restrictions (25%). The frequency of behavioral problems in children with poor fecal continence (66.7%) was significantly higher than those of children with good fecal continence (8.6%), based on a quantitative scoring of fecal incontinence. Quality-of-life scores for children with surgically corrected anorectal malformation are significantly lower than those of control subjects.  The degree of urinary control is related to the presence and severity of associated urologic defects.

Common forms of treatment

Three main elements are necessary to achieve bowel continence: functioning sphincters, normal rectal sensation, and normal rectosigmoid motility. The combination of impaired continence mechanisms, poor reservoir function, and high-amplitude propagating colonic contractions migrating to the anus (instead of ending at the level of the recto-sigmoid junction) probably explains the high prevalence of fecal incontinence in these patients. Children with anorectal malformations who suffer from defecation disorders should undergo both colonic and anorectal manometric testing to tailor better the treatment approach.

Soiling that does not require a change of underwear or that can be handled by wearing a protective pad in school is usually fairly well tolerated. Antidiarrheal agents may be used to increase the consistency of stools and facilitate continence. Anorectal biofeedback appears to be effective in some children but may not be beneficial if the sphincters are markedly hypoplastic or do not surround the anal canal. In such cases, emptying of the bowel with retrograde or antegrade enemas may have dramatic beneficial effects on the quality of life. Re-do surgeries with a variety of ingenious techniques devised to improve fecal incontinence are rarely successful. For some children with severe constipation and fecal incontinence, removal of an adynamic megarectum or megasigmoid has been associated with improvement.

Spinal problems

Spina bifida occurs in about 1 in 1000 live births, making it the most common birth defect after trisomy. Typically, it is characterized by paralysis and lack of sensation below the level of the lesion. Myelomeningocele, the most common type of open spina bifida, usually affects the lumbosacral region and is associated with bowel and bladder dysfunction. Urinary and bowel incontinence are common because the rectoanal inhibitory reflex is preserved but the urge for defecation may be lost. The external anal sphincter is often paralyzed, and, when the internal sphincter relaxes, fecal soiling is unavoidable.  Constipation may result from an increase in colonic transit time and the absence of reflex contraction in response to distension of the rectum. There is also a loss of the gastrocolonic response, which is another mechanism for constipation. Although the medical consequences of anorectal dysfunction are less serious than those of urinary dysfunction or paraplegia, the psychologic toll of such disability can be devastating to children and their families.

Children with spina bifida and fecal incontinence may benefit from techniques aimed at teaching the child how to produce a bowel movement. The child is instructed to sit on the toilet after the largest meal of the day and to contract the abdominal muscles to achieve evacuation. Initial studies suggested that biofeedback training was helpful for certain patients who had some sensorimotor function in the perianal region. Subsequent controlled studies have failed to confirm significantly improved outcomes for children who received biofeedback treatment in addition to behavior modification.

The potential for soiling can also be reduced by performing large-volume enemas. An enema continence catheter is routinely used in most centers to treat children with anorectal dysfunctions. The enema is used to empty the rectum in a retrograde fashion every 1 or 2 days. Unfortunately, patients with limb paralysis cannot self-administer such enemas without assistance. Another disadvantage is that only the left side of the colon is cleansed. Children with spina bifida can also have a continent appendicostomy (Malone procedure), which provides more complete colonic cleansing, increases the child’s autonomy, and decreases the chance of soiling.  This procedure connects the appendix to the umbilicus and uses the new orifice to administer an antegrade colonic enema (ACE) while the patient sits on the toilet. Using the ACE, the large bowel can be cleaned at regular intervals with irrigation solutions, such as polyethylene glycol, glycerin and saline, and phosphate enemas. Most patients evacuate stools within a few minutes to an hour after the irrigation solution is administered, depending on the type of solution used and the presence of normal colonic motility. Complete cleansing of the entire colon is a reliable method to avoid unpredictable “accidents.”

A cecostomy can be performed surgically, endoscopically, or radiologically to provide some of the same benefits as an appendicostomy and spare the appendix, which may be required in the future for urinary tract reconstruction. A cecostomy button is easily hidden under a shirt, and children can self-administer antegrade enemas as they get older. Satisfaction with antegrade enemas has been reported to be as high as 93% in children. Complications include leakage of the irrigation solution, development of granulation tissue, and tube dislodgement. Adverse effects include abdominal cramping and soiling after enema administration.

Miscellaneous causes

Hirschsprung disease (congenital aganglionosis) is the most common cause of lower intestinal obstruction in neonates. Theoretically, surgical removal of the aganglionic segment is a lifesaving procedure that can correct Hirschsprung disease and normalize defecation. However, defecatory problems are common even years after surgery: Up to 50% of children have constipation or fecal incontinence, regardless of the surgical technique used. The high prevalence of defecatory disturbances after surgery is due to the persistence of colonic and anorectal motor dysfunction. Surgical resection of the aganglionated rectum leads to high-amplitude propagated contractions (HAPCs) and fecal material rapidly propagating all the way to the anus. In normal individuals, HAPCs are associated with the transport of poorly formed fecal material distally. Most HAPCs originate in the proximal colon and propagate to the sigmoid colon without reaching the rectum. Among subjects who more frequently present with fecal incontinence following surgical correction, HAPCs migrate through the neorectum to the anal sphincter. Fecal incontinence occurs when the pressure of the HAPCs exceeds the voluntary contraction of the external anal sphincter. Patients also continue to have an incomplete rectosphincteric inhibitory reflex - the hallmark of the disease - after surgery, facilitating the persistence of constipation. There is also manometric evidence, and occasionally pathologic confirmation, that neuropathy may be present in the unresected, ganglionated proximal colon. A detailed evaluation of colonic motility revealed that 4 distinct motility patterns may occur in children with Hirschsprung disease after surgery.

Sphincter damage may be caused by severe perianal trauma, including penetrating and impalement injuries. These should be treated with early primary sphincter repair and a protective colostomy. Sexual abuse should also be suspected and thoroughly investigated when there is sudden onset of encopresis in the absence of other predisposing factors.

Inflammatory bowel diseases, especially Crohn’s disease with perianal involvement, may cause fecal incontinence. Fecal seepage can result from a rectocutaneous or rectovaginal fistula. Surgical treatment may be needed when medical treatment is unsuccessful. In ulcerative colitis, severe proctitis with extreme urgency may cause fecal incontinence because of poor rectal compliance and excessive colonic motor responses. Successful treatment of inflammation usually restores continence.

Research priority for anorectal formations and spinal defects

Define the role of surgical interventions - appendicostomy, cecostomy, sphincter reconstructions, colostomies - and the use of artificial sphincters in patients with anorectal malformations and spinal anomalies by designing appropriately powered controlled studies.

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Carlo Di Lorenzo and Marc A. Benninga
Division of Pediatric Gastroenterology, Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
Emma Children’s Hospital, Academic Medical Center, Amsterdam, The Netherlands