Soiling in post-op Hirschsprung's

Objective

The purpose of this guideline developed by the American Pediatric Surgical Association (APSA) Hirschsprung Disease Interest Group is to present a rational and step-wise approach to the management of post-operative soiling in children with Hirschsprung disease.

Definition

• Fecal continence = the ability to have voluntary bowel movements without soiling in the absence of an enema program.

• Fecal incontinence = (1) the inability to feel distention of the distal pull-through segment or to perceive stool contact with the anal canal , (2) inadequate anal sphincter tone, or (3) inappropriate colonic motility

• True fecal incontinence = the patients with anatomic or physiologic disruption of their continence mechanisms

• Pseudo-incontinence = the patients who have intact physiological mechanisms needed for continence, but exhibit persistent soiling after a pull-through operation

  • May be secondary to (1) obstruction/fecal impaction or (2) hypermotility of colon/neo-rectum

Causes of soiling after pull-through

1. Abnormalities in sensation

   • Inability to sense distension of the neo-rectum

   • Loss of transitional epithelium/dentate line

2. Inadequate sphincter control

   • Over stretch of sphincter mechanism during pull-through

   • Previous myectomy or sphincterotomy

3. Pseudo-incontinence

   • Obstruction/fecal impaction

   • Hypermotility

Management

• Initially requires a complete history and physical examination

  • Evaluation of the integrity of the dentate line and anal canal is mandatory through a formal examination (usually under anesthesia

  • Evaluation of anal sphincter function and sensation of the neo-rectum, may requires anorectal manometry

• Neither sphincter weakness nor poor sensation usually manages with using a bowel management program that encourages the maintenance of solid stools and promotes proper rectal emptying.

  • dietary modifcation

  • bulking agents

  • stimulant laxatives : senna or bisacodyl

  • an enema program : retrograde or antegrade via appendicostomy or cecostomy

• In severe cases, and in those where bowel management is not successful, the child may be best served by a diverting ostomy.

• If sensation and sphincter function are intact, it is useful to distinguish between soiling due to fecal impaction and soiling due to hypermotility.

• Radiographic imaging with a contrast enema may demonstrate a dilated colon and retention of contrast on a subsequent follow-up film in children with hypomotility. If the colon is non-dilated, then the problem may be hypermotility.

• If the etiology of soiling is still unclear after the contrast study, colonic manometry may be helpful.

• Children with soiling due to fecal impaction are best managed long-term with dietary modifcation including a highfber diet and stimulant laxatives.

• A complete workup for causes of constipation after a pull-through should be done to rule out mechanical obstruction, transition zone pull-through, internal sphincter achalasia, and colonic dysmotility

• Stool holding behavior may be the primary cause of soiling or may exacerbate fecal impaction in many children. Patients with Hirschsprung disease are especially prone to developing this problem because of persistent internal sphincter nonrelaxation. The anal discomfort associated with repeated use of retrograde enemas and dilations can also contribute to the development of stool holding behavior, and, if possible, the use of these techniques should be limited

• If soiling persists despite medical therapy, a large volume antegrade enema program may be needed to achieve long-term continence.

• Patients with a very dilated colon from longstanding impaction may be especially difcult to manage initially with laxatives, thus a treatment option in this group is to initiate large volume enemas for 6–12 months and then perform a laxative trial once the colon has been adequately decompressed.

• Intrasphincteric botulinum toxin injection is a useful alternative to myectomy since it reversibly relaxes the sphincter and can be repeated if successful in relieving constipation.

• If imaging or colonic manometry suggests hypermotility, the child should initially be managed with a constipating diet and bulking agents such as fber. If anti-motility agents are needed, anti-diarrheals such as loperamide or atropine/ diphenoxylate can be added. Amitryptyline may also be useful as it reduces the frequency of high amplitude contractions

Summary

A clear understanding of the underlying etiology and a stepwise, logical approach to the diagnosis and management of patients experiencing soiling following pull-through for Hirschsprung disease will facilitate efective treatment and render the majority of such patients clean and socially continent.