Encopresis

Etiology

Encopresis can be divided into constipation-associated encopresis or overflow encopresis, and non-retentive encopresis. More than 80% of the children with encopresis have retentive fecal incontinence. Other organic non-functional causes for encopresis include repaired anorectal malformation, postsurgical Hirschsprung disease, spinal dysraphism, spinal cord trauma, spinal cord tumor, cerebral palsy, and myopathies affecting the pelvic floor and external anal sphincter.[4] Encopresis in children can also be subclassified into primary, in those children who have never been toilet trained, and secondary, where incontinence returns after successful toilet training.[5]

Epidemiology

The prevalence of encopresis worldwide is estimated between 0.8% and 7.8%.[6] In the United States, a prevalence rate of 4% for functional encopresis was found in a retrospective review in four hundred and eighty-two children, 4 to 17 years of age, attending a primary care clinic. Encopresis was related to constipation in 95% of the children in this study.[7] Fecal incontinence is more common in boys, having a male-to-female ratio of 3:1 to 6:1.[6] 

Functional encopresis 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), and the majority of children seek medical care at the age of 7 to 8 years.[8] Encopresis can also be seen during the young adulthood period.[9] Encopresis usually happens during the day time, and organic causes should be considered if the provider encounters the patient who presents with only nocturnal encopresis.[10]

Pathophysiology

In the absence of organic causes, encopresis is secondary to overflow, and therefore results from the presence of constipation. Withholding of stool creates a vicious circle of accumulation of feces and hardening of the fecal mass in the rectosigmoid colon. Finally, feces leak between the solid fecal mass and rectal wall and come out through the anal canal when the sphincter muscles are relaxed. The volume of fecal matter that leaks out is usually small and, most of the time, just stain the underwear. There are different reasons why a child may withhold stool or avoid defecation.

Stool withholding may be an intentional behavior to avoid unpleasant sensations and associations with defecation. It may be due to a painful bowel movement that is caused by a stool that was larger or harder than normal, an anal fissure, or a perianal infection. The child may be reluctant to use the toilet at school due to limited time, lack of privacy, or concern about restroom cleanliness, choosing instead to withhold stool until coming home. A child may not want to have an interruption in an enjoyable activity to have a bowel movement. Finally, stool withholding may be a learned avoidance behavior that is less intentional or even unconscious due to repeated painful bowel movements.[11]

Incontinence of feces can occur during the day as well as at night time. Nocturnal incontinence is considered an indicator of severe fecal impaction in the rectum. On the other hand, children with non-retentive encopresis pass stools into inappropriate places without evidence of stool retention. The majority of them have a complete evacuation of bowel, not just staining of the underwear as in retentive incontinence. In research studies, colonic transit time appears within normal limits; however, it has been shown that there is some limitation of the relaxation on external sphincter during the defecation.[12][13] The overall pathophysiology of this pattern of encopresis is still unclear.[14] 

Risk factors for functional encopresis 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. Psychological and behavioral problems such as aggressive behavior, depression, social withdrawal, anxiety, disruptive and oppositional behavior, and poor school and social performances were noted in one-third of children with functional encopresis.[4]

History and Physical

History

The general symptoms of encopresis have been shown variably in children. The providers should always keep in mind the possibility of underlying organic causes as well. In general, encopresis is a clinical diagnosis that is primarily based on symptoms in the absence of red flag symptoms, and most patients do not need further testing.

The provider should perform a comprehensive assessment with an extensive medical history, including the history of rectal or anal surgery due to possible malformation or congenital disabilities. The age of onset, the characteristic features of stool, including size, frequency, consistency, and presence of blood or defecation problems, are the essential part of the assessment. The consistency and amount of stool, in addition to the frequency of the episodes either during day time or night time, should be assessed. Watery encopresis may be perceived as enuresis by parents at times. Clinical providers should determine the possible local or systemic symptoms such as poor appetite, stomachache, increased temperature, nausea, weight gain problem, and other psychiatric presentations.[15][16][17] 

The patient may present with diurnal or nocturnal enuresis and other urinary infections in children with chronic constipation and soiling problem.[18] The detailed history of current and previous diets and attempted successful or unsuccessful treatment strategies for soiling or constipation should be gathered. Providers should evaluate for a history of psychological trauma or new-onset life stressors such as bullying, losing close family members, or parental separation.[19]

Physical Examination

A detailed physical examination is one of the essential steps in the assessment. During the abdominal examination, the provider would be able to obtain vital information about the severity of the fecal impaction and gas accumulation.[20] Perianal area inspection can provide useful clues such as skin color changes, irritation, anal malformation, or fissures with or without hemorrhoids. Digital rectal assessment should be done to assess the sensory changes in the perianal area along with the position and the caliber of the rectum. Anal sphincter anatomy and functionality should also be evaluated. Lastly, the examination should be finalized with an inspection of the lumbosacral area. Finding a sacral dimple that is accompanied by hair may be seen in the spinal cord defects such as spina bifida occulta.[21]

Evaluation

Encopresis is mainly a clinical diagnosis, and the majority of patients do not need any further testing. North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) included in their recommendations that routine laboratory testing to screen for hypothyroidism, celiac disease, and hypercalcemia in the absence of alarm symptoms is not recommended for constipation, which leads to the majority of encopresis cases in children.[22] Radiography is helpful only for determining the presence of a fecal mass in rectum 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.[23][24] De Lorijn et al. suggested that a bowel diary is sufficient to diagnose constipation and encopresis.[25] 

A recent study involving children with defecation disorders 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.[26]

Anorectal manometry can be used as a beneficial tool for patients with chronic constipation. Fundamentally, anorectal manometry assesses the anal pressure and rectal sensation. In clinical practice, sphincter muscles may need assessment when there is a spinal cord injury or local injuries in sphincter muscles. The internal anal sphincter may lose the ability to relax in a patient with Hirschsprung disease during the rectal balloon distention test.[27]

A barium enema should not be done in patients with mild constipation. It should be used in the assessment of the caliber of small or large intestines, which may provide beneficial clinical findings in the suspicion of  Hirschsprung disease or evaluation of anal atresia after the surgical intervention.[28]

Treatment / Management

Due to the majority of the children having a diagnosis of retentive fecal incontinence, the treatment for encopresis relies on treating the root cause, which is chronic constipation. Management of constipation is covered in a different section in Statpearls, Pediatric Functional Constipation.[29] The recently published NASPGHAN guidelines include four important phases in the treatment of chronic constipation: (1) education, (2) disimpaction, (3) prevention of reaccumulation of feces, and (4) follow-up.[22]

Providers must explain that constipation often leads to a vicious cycle that results in stool withholding, fecal retention, and eventually encopresis. It is essential to clarify to the family that fecal incontinence is caused by rectal impaction and is beyond the child's control. It should also be stressed that maintenance therapy usually takes 6 to 24 months. In most cases, a detailed plan eliminates the frustration of parents and children and improves compliance necessary for the prolonged treatment.

Disimpaction, or removal of the fecal impaction, is recommended before maintenance therapy.[22] Fecal disimpaction can be accomplished with oral, or rectal agents. Oral administration of laxatives is less invasive and is more cost-effective than enemas or manual disimpaction.[30] The use of orally administered polyethylene glycol (PEG) for fecal disimpaction is effective and safe.[31](A1)

The next step of treatment focuses on the prevention of recurrence, which can be achieved through a combination of dietary changes, behavioral interventions, and medication. Although diet modification is very popular, the data is lacking to support supplementation with fiber, extra fluids, prebiotics, or probiotics.[22] Therefore, providers should recommend a healthy and balanced diet in general. Behavioral interventions include positive feedback and reinforcement from parents, addressing coexisting behavioral problems and psychological referrals if needed. Biofeedback training is a technique that can be used to teach children how to control their perianal muscles to pass bowel movement more efficiently.[32](A1)

Oral daily laxative therapy should be initiated immediately after disimpaction. The laxative dose should be adjusted as needed to reach the desired stool consistency and frequency. These medications include mineral oil, osmotic laxatives (such as lactulose, magnesium hydroxide, and PEG) and stimulant laxatives (such as senna and bisacodyl).

Although conventional therapy usually successfully treats children with constipation induced encopresis, a small group continues to have intractable symptoms. Surgical interventions may benefit this minority, including intrasphincteric injection of botulinum toxin (Botox), antegrade enemas, and rectosigmoid resection.

The treatment of non-retentive encopresis has not been well defined. The treatment consists of education, keeping a bowel diary, and toilet training four times a day following meals and immediately after arriving home from school.[9] Sometimes antidiarrheal drugs, such as loperamide, are prescribed for children with fecal incontinence to reduce the fecal output.[33] Behavioral therapy of toilet training, in combination with a reward system, is the most critical step in the management of non-retentive encopresis.[34] Currently, surgical interventions have no place in the treatment of children with non-retentive encopresis.(B3)

Differential Diagnosis

The differential diagnosis for encopresis includes organic non-functional causes such as:

• Repaired anorectal malformation
• Postsurgical Hirschsprung disease
• Spinal dysraphism
• Spinal cord trauma
• Spinal cord tumor
• Cerebral palsy
• Myopathies affecting the pelvic floor and external anal sphincter[4]

Pertinent Studies and Ongoing Trials

The criteria for diagnosing functional gastrointestinal disorders was recently updated (Rome 4 criteria).[35] Severe encopresis remains a disabling condition for patients and a major therapeutic challenge for providers. A recent prospective, randomized, controlled clinical trial of placement of the artificial bowel sphincter (Acticon Neosphincter) for the control of fecal incontinence in adults revealed that the intervention is safe and effective when compared with supportive care alone.[36]

Another randomized controlled trial was conducted to evaluate the contribution of the anal plug to the management of fecal incontinence in children and adults, and it has been found that anal plug is of benefit to the majority of patients.[37] These surgical interventions, although still in a very early stage, might provide more effective treatment, especially for non-retentive encopresis.

Prognosis

Most children treated for retentive encopresis are eventually cured, although the time required for treatment varies, and relapses are frequent. A systematic review found that only half of all children with constipation followed for 6 to 12 months after therapy did well without laxatives. Treatment needs to resume if constipation or fecal incontinence recurs. Early age of onset of constipation and family history were predictive of the persistence of symptoms.[34] 

On the other hand, there is little evidence about the long-term outcome in children with non-retentive encopresis. In one study where children with non-retentive encopresis were followed for ten years, only 29% of children were having less than one episode of fecal incontinence in two weeks after two years of medical and behavioral therapy. At the age of 18 years, 15% of children progressed to adulthood with fecal incontinence. No prognostic factors for success were found in this study.[34]