Carol D. Berkowitz, MD, FAAP
A 7-year-old boy is seen with a report of soiling his underpants. His mother states that he has never been completely toilet trained and that stool-related accidents occur at least 2 to 3 times a week, mainly during the day. The boy rarely has a spontaneous bowel movement without assistance. He sits on the toilet for just a few minutes and passes small, pellet-like stools. His mother has not previously sought medical care for this problem.
The boy is quite fidgety during the physical examination. His vital signs are normal, and his height and weight are at the 25th percentile. His abdomen is soft but distended, with palpable loops of stool-filled bowel. A small amount of stool is present around the anus and in the boy’s underpants. Digital examination of the rectum reveals hard stool. The rectal tone is normal, as is the rest of the physical examination.
1. What is the definition of encopresis?
2. What is the difference between retentive and nonretentive encopresis?
3. What are some physiologic conditions that contribute to encopresis?
4. What conditions may be mistaken for encopresis?
Encopresis is the voluntary or involuntary repeated passage of stool into inappropriate places (eg, clothing) in children who, based on their age, should be toilet trained (usually at least 4 years of age, the age at which 95% of children have achieved stool continence) and who exhibit a normal developmental level and who have no primary organic pathology. One such encopretic event occurs each month for at least 3 months. The term encopresis, which was coined in 1926 by Weissenberg and originally was used for children with psychogenic soiling, is similar to enuresis (ie, urinary incontinence). Unlike enuresis, however, encopresis rarely occurs at night. Currently, “encopresis” is used in a broader sense to refer to all types of fecal incontinence. “Functional fecal incontinence” is the currently preferred term as recommended by the Multinational Working Teams to Develop Diagnostic Criteria for Functional Gastrointestinal Disorders.
Retentive encopresis, also referred to as functional fecal retention with encopresis or retentive fecal incontinence, occurs in the setting of functional constipation (ie, obstipation), in which chronic rectal distention results in the seepage of liquid stool around hard, retained feces. Sometimes this is called “overflow,” “fecal soiling,” or “pseu-doincontinence,” because the individual has the potential for bowel control. Onset of symptoms is usually approximately 4 years of age. Between 80% and 95% of cases of fecal incontinence are retentive. Nonretentive fecal incontinence is characterized by the passage of soft stool without colonic distention or retention of stool. Fecal incontinence in the absence of constipation is reported in up to 20% of children with encopresis. There are 2 categories of children with nonretentive fecal incontinence: those who can control defecation but who pass stool in inappropriate places and those who have true failure to achieve bowel control. Primary encopresis occurs when a child has never been completely toilet trained. Secondary encopresis occurs in a child who has had a period of complete continence of stool. Most children with encopresis have the secondary form.
Encopresis is reported in approximately 1.5% of school-age children, and boys are affected 2 to 6 times more often than girls. This sex ratio reverses in the elderly, in which the prevalence of fecal incontinence is twice as high in females as in males. An association between encopresis, enuresis, attention-deficit/hyperactivity disorder, and autism spectrum disorder is sometimes present. Approximately 15% of children with enuresis also have encopresis. Family history for encopresis may also be positive; 16% of affected children have 1 affected parent (usually the father). An association between encopresis and child sexual abuse has been reported in a small number of children. No reported relationship exists between socioeconomic status, parental age, child’s birth order, or family size.
Children with encopresis have a history of staining of the underpants, which may be hidden in drawers or under beds by embarrassed children. Occasionally, parents are unaware of the problem. Stool incontinence occurs more frequently at home than in school. Some children have a history of constipation. Other children may be initially misdiagnosed as having diarrhea and are inappropriately placed on antidiarrheal medications, which exacerbate their problem. Parents may complain that their child exudes a fecal odor, but children are unaware they are malodorous (Box 56.1). Approximately one-half of children with encopresis report abdominal pain, which may be vague and nonspecific or severe and crampy. Approximately 30% to 35% experience urinary incontinence or have a history of urinary tract infections (UTIs).
The 3 identified milestones at which a child may be at risk for the development of functional constipation are the introduction of dietary solids into an infant’s diet, toilet training, and the start of school. Other factors that may precipitate secondary encopresis include change in schedule (eg, overnight school trips with use of communal bathrooms) and parental separation. Constipation, if associated with painful defecation, may contribute to the manifestation of retentive fecal incontinence. With time, the colon dis-tends and liquid feces seeps around impacted stool (Figure 56.1). In 30% to 50% of children anal spasm (ie, anismus) occurs, and contraction rather than relaxation occurs during evacuation of feces. In another 40% of children, rectal hyposensitivity is apparent, resulting in unawareness of the presence of stool. Some children have an evacuation release disorder in which the presence of stool does not result in relaxation and stool evacuation. In such cases, the rectum is chronically distended by stool, water is absorbed, and stool becomes harder and drier. The distended rectum cannot sense the presence of the stool. When evacuation is attempted, the process is painful, resulting in further retention (see Chapter 124).
Box 56.1. Diagnosis of Encopresis
•Incontinence of stool
•Stool-filled loops of bowel
•Lax rectal tone
•Soiled clothing or bedding
Encopresis has been associated with a short attention span and a high level of motor activity. Affected children are unable to sit on a toilet for more than a few minutes and do not adequately attend to the task of stool evacuation. As a result, they get off the toilet after the incomplete evacuation of only small amounts of stool. In some toddlers, constipation is related to the struggle of toilet training and an unwillingness to sit on the toilet (see Chapter 48).
Figure 56.1. Diagram of the rectum, anal canal, and sigmoid colon distended with stool.
The etiology of nonretentive encopresis is unclear; however, 40% of children with nonretentive encopresis have never been adequately toilet trained. Comorbid psychiatric disorders as well as a history of sexual abuse have also been reported. Some children who have been chronically sexually abused have lax anal tone, which may contribute to fecal incontinence. A small proportion of children with nonretentive encopresis have a history of prior surgery in the rec-tosigmoid colon for the management of conditions such as congenital megacolon (ie, Hirschsprung disease) and imperforate anus. The child with acute proctitis secondary to cow milk protein allergy or inflammatory bowel disease may experience fecal incontinence; in this setting often the stool is also blood-tinged.
The differential diagnosis of encopresis focuses on organic conditions associated with chronic constipation. Organic conditions, which account for 5% to 10% of fecal incontinence, include congenital megacolon (ie, Hirschsprung disease), disorders of intestinal motility (eg, pseudo-obstruction), disorders of anal tone and anal anatomy (eg, imperforate anus with fistula), disorders of the lumbosacral spine (eg, meningomyelocele), previous surgeries (eg, repair of imperforate anus) and neurologic disorders (eg, intellectual and developmental disabilities, hypotonia). Neurofibromatosis, lead poisoning, and hypothyroidism are also associated with constipation. Congenital anorectal anomalies, which occur in 1 in 5,000 live births, are rare.
Most of these conditions can be ruled out on the basis of a careful history and physical examination. In some cases, specific testing, such as anal manometry or rectal biopsy, may be necessary to exclude a particular disorder.
The physician should determine the age of onset of fecal incontinence as well as the age of initiation of toilet training. Generally, affected children are 4 years of age or older. A detailed history of the stool pattern should be obtained as well as a dietary history (Box 56.2). The frequency, consistency, and quantity of stools should also be noted. Additionally, the presence of nocturnal episodes of fecal incontinence should be determined. In cases of secondary encopresis, the duration of prior fecal continence and the occurrence of any events (eg, birth of a sibling, start of school) that may have precipitated the episodes of encopresis should be noted. Some children experience the onset of encopresis when they start school. Because of “toilet phobia,” they are unwilling to use the public toilet in the school setting. It is important to note that not all children who experience constipation develop encopresis.
A comprehensive physical examination is necessary, paying particular attention to the abdomen to check for the presence of distended, stool-filled loops of bowel. Fifty percent of children with retentive encopresis have a palpable fecal mass. The rectal area should be assessed for rectal tone, anal wink, and the presence of hard stool (which may be noted in up to 90% of children with encopresis). To elicit an anal wink, the skin adjacent to the anus should be stroked using a cotton swab. Some children with retentive encopresis may forcibly tighten their anal sphincter and their buttocks in response to a digital examination or because they are frequently contracting their external anal sphincter to prevent the seepage of liquid stool.
Box 56.2. What to Ask
•At what age was the child toilet trained?
•Does the child have spontaneous bowel movements (without enemas or suppositories)? If so, how frequently?
•Does the child have large, dry, hard stools that clog the toilet?
•Does the child pass blood with the stool?
•Did the child pass meconium within the first 24 hours after birth?
•Has the child had any surgery in the anogenital area, spine, or bowel?
•Is the child taking any medication that can promote constipation, such as aspirin, iron, methylphenidate hydrochloride, imipramine, calcium channel blocking agent, or an anticholinergic agent?
•Does the child seem to resist the urge to defecate (eg, squeezes legs together and rocks back and forth)?
•Does the child have a history of enuresis or attention-deficit/hyperactivity disorder?
•What is the pattern of encopresis (ie, is the encopresis primary or secondary)?
•When and where does the child soil (eg, nocturnal, at home)?
•Have changes or stresses occurred in the home or family?
•What happens to the child’s stained underwear?
•What has the family done to manage the problem?
•What is the child’s diet? How much milk does the child drink? Does the child eat fruits and vegetables?