Severe Pediatric Constipation

Updated: Nov 29, 2017
  • Author: Marc A Levitt, MD; Chief Editor: Harsh Grewal, MD, FACS, FAAP  more...
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Overview

Background

Constipation is an extremely common problem in the pediatric population. Most constipated pediatric patients can be treated with simple measures (eg, dietary changes and laxatives), but a significant number have severe constipation and require more aggressive treatments, and some even need surgery. Most have functional (idiopathic) constipation, which has a wide spectrum of severity. A small number of patients have very severe bowel dysmotility and overlap with the group of patients considered to have intestinal pseudo-obstruction.

In addition to patients with functional constipation, patients who have undergone surgery for anorectal malformations, as well as those with Hirschsprung disease, [1, 2] can suffer from severe constipation and incontinence. Management of patients with these surgical problems has greatly informed the care of patients with idiopathic constipation.

If the patient is not toilet-trained by age 3 years and the family wishes the child to be rendered clean, the clinician can offer an artificial way to keep the patient clean and socially continent. This regimen essentially involves teaching the family and patient how to clean the colon once a day with an enema and how to manipulate the colonic motility with diet, medications, or both when necessary to ensure that the patient does not pass stool between enemas.

Understanding the difference between fecal incontinence and the phenomenon known as overflow pseudoincontinence or encopresis (which is a sequela of a severe inertia of the rectosigmoid) is vital because management approaches to these two types of patients differ significantly.

For patients who lack the capacity for voluntary bowel movements and thus cannot voluntarily empty their colons, fecal incontinence requires a mechanical bowel management regimen that involves daily enemas. Patients with incontinence due to severe constipation may have overflow pseudoincontinence; once their constipation is managed, they may be able to have voluntary bowel movements. Such patients require a bowel management regimen that involves laxatives, which help them regularly and voluntarily empty their colon.

Medical treatment with enemas, laxatives, and medications has traditionally been used for patients with soiling, with varying degrees of success. [3, 4] These treatments are often used without a specific rationale in an indiscriminate manner that often reflects a lack of understanding of the difference between patients with overflow pseudoincontinence and those with real fecal incontinence.

Bowel management with an organized protocol that is implemented by a thoughtful team of physicians and nurses can have a dramatic impact on a patient with fecal incontinence. Likewise, bowel management in a patient with overflow pseudoincontinence can treat the impaction, avoid constipation, and promote the conditions needed for fecal continence.

The process of bowel management in patients with fecal incontinence is one of trial and error. With the described protocol, the vast majority of patients have success and can live reasonably normally with a good quality of life.

Better understanding of the causes of poor colonic motility will dramatically improve its treatment. The ideal management for these patients would be pharmacologic agents that can induce a single colonic contraction with complete emptying of the colon and then keep the colon quiescent for the next 24 hours. If such a regimen existed, incontinence would be cured.

Most likely, there are histologic abnormalities that explain slow colonic motility but remain undetected with current histologic techniques. Motility studies of the colon are able to show which segments of the colon are responsive to stimulants (eg, bisacodyl and glycerin). Such studies can be used to guide medical and surgical treatment, though their interpretation is still being refined. In time, these studies could clearly show whether laxative antegrade enemas or resection of a part of the colon should be part of the treatment plan.

Eventually, an understanding of genetics will play a role in the prevention of this condition. Future developments in these areas will dramatically affect the quality of life for many children.

For more information on these topics, see Constipation and Pediatric Constipation.

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Pathophysiology

Bowel motility is one of the most complex and sophisticated functions in the human body. The colon absorbs water and functions as a reservoir. Liquid waste delivered by the small bowel into the cecum becomes solid stool in the descending and sigmoid colon.

The colon has relatively slow motility; peristalsis seems to be less active in its distal portions. Normally, the rectosigmoid remains quiet for periods of 24-48 hours. Active peristaltic waves then develop, indicating that the rectosigmoid must be emptied. This development is perceived by the individual, who then has the capacity to voluntarily retain the stool up to a point or to empty it, depending on social circumstances.

To achieve fecal continence, the following three components are necessary:

  • Sensation within the rectum
  • Reliable motility of the colon
  • Good voluntary muscle or sphincter control

Children who have anorectal malformations lack some or all of these essential components. Children who have undergone pelvic surgery for Hirschsprung disease may have injury or loss of some of these components as a consequence of their surgical treatment (most importantly, their sphincters and anal canal up to the dentate line).

All patients born with anorectal malformations (except those with pure rectal atresia, which is rare) are missing the anal canal; thus, they do not experience the exquisite sensation in this area that is very important for continence. They lack the intrinsic sensation associated with stool or gas passing through the rectum. Therefore, they may soil themselves unknowingly.

In a child with an anorectal malformation whose rectum has been correctly placed within the sphincter mechanism, distention of the rectum stretches the voluntary muscles that surround the rectum and gives the child proprioception, which is another vital component of continence. The sphincter mechanism in children with imperforate anus varies across a broad spectrum, ranging from a mechanism similar to that observed in a child with bowel continence to a near-total absence of muscles in the perineum.

In patients with anorectal malformations, the presence of a preserved rectal reservoir plays a pivotal role. Poorly developed muscles, which are often associated with a hypodeveloped sacrum or spine and vertebral problems (eg, hemivertebrae, tethered cord, or myelomeningocele), clearly contribute to the potential for fecal and urinary incontinence.

Patients with anorectal malformations and Hirschsprung disease may have abnormal peristaltic waves in the colon, which result either in stagnant stool or in an overactive colon. The child then develops constipation or overflow pseudoincontinence (encopresis). Alternatively, a very active colon may provoke a constant passing of stool, which may significantly interfere with bowel continence.

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Etiology

Functional constipation is an inability to pass stool or difficulty with passing stool regularly and efficiently. The etiology of this condition is unknown. It is by far the most common defecation disorder and the most common colonic motility disorder in children. Constipation affects an enormous pediatric population and represents a very common cause for surgical consultation.

Constipation is relevant not only because it affects millions of patients but also because it is extremely incapacitating in its most serious form. It can produce overflow pseudoincontinence, or encopresis (with soiling), which must be distinguished from true fecal incontinence. Also, the most serious type of constipation overlaps with intestinal pseudo-obstruction, a very serious motility disorder that also involves the stomach and small bowel and that carries a significant morbidity.

Even though the cause of this condition is unknown, the literature presents many potential causes for the disease, most of which have no solid scientific basis.

Many publications discuss dietary disorders as a cause of constipation. Different types of food have either a laxative or constipating effect on the body, and diet is certainly important for regulating colonic motility; however, the therapeutic value of diet is negligible in the most serious forms of constipation. Thousands of patients with mild forms of constipation are successfully managed with dietary measures alone. However, patients in whom surgery is indicated have a much more serious form of this condition that does not respond to dietary treatment alone.

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