What Is Dyssynergic Defecation?

Formerly Known as Anismus

doctor with female patient
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Dyssynergic defecation, previously known as anismus, is a health condition that can result in the experience of chronic constipation. Dyssynergic defecation is considered to be the result of pelvic floor dysfunction, in that the muscles and nerves within the pelvic floor are not functioning as they should.

In specialized tertiary care treatment centers, dyssynergic defecation is diagnosed in approximately half of the patients seeking treatment for chronic constipation.

Dyssynergic defecation has been found to result in negative quality of life, affecting the work and social lives of those diagnosed with the disorder.

Symptoms of Dyssynergic Defecation

As you will see, the symptoms of dyssynergic defecation parallel those of chronic constipation.

A Small Biology Lesson

It helps to better understand the problem of dyssynergic defecation if you can visualize what the lower end of your digestive system looks like. As you can see in the image above, your rectum lies at the bottom of your long intestine. The rectum stores stool and is the passageway for stool to make its way out through your anal canal, where it ultimately exits through your anus.

Muscles within the pelvic floor, including those of your abdomen, rectum and anus, must all work together for the coordinated passage of stool.

The muscles of your anal canal include the levator ani muscles and the puborectalis muscle. The anal canal also has two sphincters, an internal sphincter and an external sphincter, which help us maintain continence.

What's Going Wrong?

In dyssynergic defecation, it appears that the coordination between the muscles that make up the pelvic floor is impaired.

In attempting to understand what is going wrong in dyssynergic defecation, specific attention is given to the puborectalis muscle and the internal and external sphincters of the anus. Improper contraction and/or relaxation of these muscles during bowel movements appear to be major contributors to the problem.

To complicate things further, there is some evidence that some individuals who suffer from dyssynergic defecation have an impairment in their perception of stool within the rectum. This may lead to missing cues about the need to initiate a bowel movement, thus exacerbating the constipation problem.

To sum it up, dyssynergic defecation is the result of the following problems:

  • Impaired awareness of the need to defecate
  • Impaired pushing
  • Rectal contraction is inadequate
  • Contraction of the puborectalis muscle when it should be relaxing
  • Contraction of the internal and external sphincters when they should be relaxing
  • A combination of any of the above factors

Possible Causes of Dyssynergic Defecation

In many cases, no specific factor can be identified as causing dyssynergic defecation.

For some people, the problem begins in childhood. Other causes have been noted:

  • Childbirth
  • Pregnancy
  • Rectal injury
  • Repeated passage of hard stool
  • Sexual abuse

What To Do If You Suspect You Have Dyssynergic Defecation

Speak with your doctor if you suspect that your constipation problem may be the result of dyssynergic defecation. Your doctor may recommend some diagnostic procedures and then will work with you to devise a treatment plan.

Alternate Names

The condition of dyssynergic defecation has been called by a wide variety of names over the years, including:

  • Anal sphincter dyssynergia
  • Anismus
  • Obstructive defecation
  • Paradoxical puborectal contraction
  • Pelvic floor dyssynergia
  • Pelvic outlet obstruction
  • Spastic pelvic floor syndrome


Cheung, O. & Wald, A. "The management of pelvic floor disorders" Alimentary Pharmacology and Therapeutics 2004 19:481-495.

Rao, S. "Pelvic Floor Dysfunction" Revista de Gastroenterologia de Mexico 2010 75:72-82.

Shim, L., et.al. "Predictors of outcome of anorectal biofeedback therapy in patients with constipation" Alimentary Pharmacology and Therapeutics 2011 33: 1245-1251.

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