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Imperforate anus repair

Alternative names

Anorectal malformation repair; Perineal anoplasty


Imperforate anus repair is surgery to correct birth defects involving malformation of the rectum and anus.

Normally, the large intestine (colon) empties into a pouch-like portion of bowel (rectum). Through complex nerve and muscle structures, the rectum releases stool through the anus out of the body.

Infants with imperforate anus defect, however, have malformations of the rectum and anus, in which abnormal development of these structures leads to growth of skin over the anus, and incomplete development of the rectum.

As a result, these infants have either no anal opening through which stool can pass or a very small opening with fistulas (channels that connects skin to bowel) that allows only a small amount of stool to pass out of the rectum.

Variations of the defect include:

  • Complete absence of an anal opening
  • A small tube-like opening ( fistula ) from the bowel to the skin, vagina, or urethra
  • Rectum ends above the pelvic nerve and muscle structures ("high type" imperforate anus)
  • Rectum extends completely or partially through the pelvic nerve and muscle structures ("low type" imperforate anus)


Surgical repair involves creating an opening for the passage of stool. Complete absence of an anal opening requires emergency surgery for the newborn.

Surgical repairs are performed while the baby is under general anesthesia.

Surgery for a high type imperforate anus defect usually involves creation of a temporary opening of the large intestine (colon) onto the abdomen to allow passage of stool. This is called a colostomy . The baby is allowed to grow for several months before attempting the more complex anal repair.

The anal repair involves an abdominal incision, which loosens the colon from its attachments in the abdomen to allow it to be repositioned. Through an anal incision, the rectal pouch is pulled down into place, and the anal opening is completed. The colostomy may be closed during this stage or may be left in place for a few more months while the tissues heal, and closed at a later stage.

Surgery for the low type imperforate anus (which frequently includes a fistula ) involves closure of the fistula, creation of an anal opening, and repositioning the rectal pouch into the anal opening.

A major challenge for either type of defect and repair is finding, using, or creating adequate nerve and muscle structures around the rectum and anus to provide the child with the capacity to move his or her bowels normally.


This surgery is recommended to repair cases of imperforate anus and other anorectal malformations .


Risks for any anesthesia include the following:
  • Reactions to medications
  • Problems breathing
Risks for any surgery include the following:
  • Bleeding
  • Infection
Other risks include the following:
  • Damage to the supporting muscles in the pelvis
  • Damage to the urethra
  • Temporary postoperative paralysis of the bowel ( paralytic ileus )

Expectations after surgery

Most anorectal malformations can be corrected successfully with surgery. Normal bowel function can be established in most cases. The long-term expectations are excellent if no other pelvic abnormalities are found.


The child may spend several days in the hospital. Dilatation of the new anus (to improve muscle tone and to prevent narrowing) will be performed in the hospital and will need to be continued for some months. Use of stool softeners and a high-residue diet will need to continue throughout childhood.

Update Date: 2/10/2003

James P. Dolan, M.D., Department of Surgery, University of California, San Francisco, San Francisco, CA. Review provided by VeriMed Healthcare Network.

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Last updated: Tue, 06 Jan 2009 00:20:03 GMT