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Imperforate anus

translations available: Spanish

What is imperforate anus?

Imperforate anus occurs when the anal opening is absent or not in a normal position. It is a birth defect caused by the failure of normal development of the anal area. Sometimes a fistula (abnormal passage) is present between the bowel and the vagina in girls, or between the bowel and the urinary tract in boys. There are three types of imperforate anus:

  • High type - no anal opening is present and the rectum ends above the muscles at the bottom of the pelvis (hip bones). These children may have a fistula.
  • Intermediate type - the end of the rectum and anal canal extend through the muscle at the bottom of the pelvis. These children may have a fistula.
  • Low type - the rectum ends below the muscles at the bottom of the pelvis. There is often an anal opening present, but it is in an abnormal position or is covered by a membrane.

What causes an imperforate anus?

There is no known cause for the condition, which occurs in 1 out of every 5,000 infants.

What are the symptoms?

  • no anal opening
  • misplaced anal opening 
  • anal opening very near the vaginal opening in a female
  • no bowel movement within 24 to 48 hours after birth
  • stool passed through the vagina or urethra
  • abdominal distension (bloating)

How is it diagnosed?

Diagnosis is made at birth when the anal opening is checked during the newborn's physical examination.

What is the treatment?

The low type may be corrected by one or more of the following:

  • opening the membrane in surgery
  • repeated dilating (stretching) of the opening
  • surgical reconstruction
  • The high type is corrected with surgeries over a period of time.
  • A temporary colostomy (re-routing the bowel out through the abdominal wall) is created. The baby then has bowel movements into a pouch (ostomy bag).
  • At about 3 to 9 months of age, surgical reconstruction of an anal opening is performed, and any possible fistula is closed.
  • The colostomy is reconnected 6 to 8 weeks later.

If your child needs a colostomy, a WOCN (Wound Ostomy Continence Nurse) will teach you how to take care of the colostomy and how to apply the pouch. See the education sheet, "Pouch change". You will be able to practice taking care of the stoma before your baby goes home from the hospital.

What else do I need to know?

  • The outcome is good with treatment. Children with imperforate anus are often constipated, even after surgical repair. In these children, a bowel management program may be needed to treat constipation.
  • Stool incontinence is by far the most troublesome complication.
  • Children with the low type usually gain bowel control. Only a few with the high type have normal bowel control by school age,
    but it usually improves by adolescence (the teenage years).
  • When your child's specific needs are determined, the health care team will work with you and your child through the steps of a successful bowel management program.


This sheet is not specific to your child but provides general information. If you have any questions, please call the doctor.

Children's Hospitals and Clinics of Minnesota
Patient/Family Education
2525 Chicago Avenue South
Minneapolis, MN 55404

Last reviewed 7/2015 © Copyright

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This page is not specific to your child, but provides general information on the topic above. If you have any questions, please call your clinic. For more reading material about this and other health topics, please call or visit Children's Minnesota Family Resource Center library, or visit

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