About Continence :: Nationwide Children's Hospital

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How does continence work?

When it comes to eliminating feces (solid waste), the body goes through a series of complicated processes which depend on voluntary muscle control, sensation and involuntary movements of the colon (motility) that push stool along.  Toilet training and bowel control are only able to happen when these three things are working together properly.  An issue with just one part of the process can lead to bowel problems like constipation or fecal incontinence.

Voluntary Muscles
Once the large intestine has pushed the stool to the anorectal area, sphincter muscles that control feces leaving the body are used. Children are able to voluntarily control those muscles to hold stool, or relax the muscles to go to the bathroom. Sometimes these sphincter muscles can be weak in children born with an anorectal malformation/imperforate anus or spinal problems. If a child chooses to hold stool too often, it can lead to chronic constipation.

Sensation
In order to know when to use sphincter muscles the child must first feel something in the area, a sensation provided by the anal canal.  This part of the body provides detailed sensory information to the brain to let it know when it’s “time to go.”

Surgery to correct anorectal malformations or Hirschsprung disease, or certain types of spinal problems can reduce sensation in the anal canal, so the brain does not get the message when the rectum is full of stool.

Motility (Slow or Fast)
Bowel issues can also be triggered by how fast the colon pushes feces through to the rectum (the last segment of the large intestine) before it reaches the sphincter muscles.

  • Hypomotility: In patients where the colon pushes stool slowly (hypomotility), feces tends to gather in the rectum – which is larger than normal in most such patients. These children may not be able to feel the fullness, developing severe constipation and then soiling due to overflow. The issue can also develop in children who don’t have any malformations and have never had surgery. In this case, the soiling due to idiopathic (unknown cause) constipation is called encopresis. Treatment for these patients with slow motility can involve diet changes, medication, treatments and bowel management programs that help prevent constipation.
  • Hypermotility: Patients who may have had surgery that removed parts of their colon have the opposite problem from those with hypomotility, and stool moves through too fast (hypermotility). This can result in loose, watery stools that can leak out of the anus. Treatment for this may involve diet modifications and medication.
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