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Imperforate anus



Imperforate anus is congenital (present from birth) defect in which the opening to the anus is missing or blocked. The anus is the opening to the rectum through which stools leave the body.

Alternative Names

Anorectal malformation; Anal atresia


Imperforate anus may occur in several forms. The rectum may end in a blind pouch that does not connect with the colon. Or, it may have openings to the urethra, bladder, base of penis or scrotum in boys, or vagina in girls. A condition of stenosis (narrowing) of the anus or absence of the anus may be present.

The problem is caused by abnormal development of the fetus, and many forms of imperforate anus are associated with other birth defects. It is a relatively common condition that occurs in about 1 out of 5,000 infants.

  • Anal opening very near the vaginal opening in girls
  • Missing or misplaced opening to the anus
  • No passage of first stool within 24 - 48 hours after birth
  • Stool passes out of the vagina, base of penis, scrotum, or urethra
  • Swollen belly area
Signs and tests

A doctor can diagnose this condition during a physical exam. Imaging tests may be recommended.

Support Groups

Expectations (prognosis)

With treatment, the outcome is usually good. However, it depends on the exact problem. Some infants may never develop adequate bowel control.

Calling your health care provider

This disorder is usually discovered when the newborn infant is first examined. Call your health care provider if a child that was treated for imperforate anus has abdominal pain or fails to develop any bowel control by the age of 3.

  • Bowel incontinence
  • Constipation
  • Intestinal blockage

The infant should be checked for other problems, especially those affecting the genitals, urinary tract, and spine.

Surgical reconstruction of the anus is needed. If the rectum connects with other organs, repair of these organs will also be necessary. A temporary colostomy is often required.


As with most birth defects, there is no known prevention.


Klein MD, Thomas RP. Surgical conditions of the rectum, anus, and colon. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 341.

Review Date: 5/12/2009
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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