Imperforate Anus

Overview

Imperforate Anus is an abnormality of the anus and rectum that is present at birth. The infant is born without a normal rectal opening. Another name for imperforate anus is "anorectal anomaly." In most cases the imperforate anus is obvious on the first day of life as the infant has no anal opening or, the rectal opening is abnormally placed. Occasionally infants are not diagnosed until several months of age. There is variation in the degree of abnormality of the rectum. It may vary from a low imperforte anus where the rectum may be in the normal location but is too tight to allow the infant to have a bowel movement; to an intermediate imperforate anus where the opening is too close to the urethra; to a high imperforate anus where the rectal opening is completely absent.

Occurrence

Anorectal malformations occur in one in 5,000 live births. There is no known cause. Anorectal malformations occur slightly more commonly in males. Males are twice as likely to have a high or intermediate anorectal abnormality.

Diagnosis

A thorough history and physical examination are necessary for the surgeon to make a diagnosis and develop a treatment plan. It may be necessary to obtain additional diagnostic testing. Each type of anorectal malformation requires a different operation and medical management.

History

The surgeon will ask questions regarding frequency of stools, passage of meconium and, straining with stooling.

Physical examination

The Pediatric Surgeon examines the abdomen and visually locating the rectal opening. If the rectal opening is identified, it may be probed with a finger or a surgical instrument. With a low imperforate anus, the physician will usually see an anal opening which varies in location on the perineum and size. However, a child with a high imperforate anus may have a perineum with a flat, or "rocker bottom" appearance.

Radiological Tests

May be needed to identify the child's anatomy. These tests include abdominal x-ray, a barium enema or, a "fistula-gram."

Exam under anesthesia

Children with intermediate or high imperforate anus may require an exam under anesthesia to complete the diagnosis.

Associated Anomalies

About one half of the children with an imperforate anus have other associated medical problems. Once the diagnosis of imperforate anus is made, other tests are done to look for these problems. They often use the term "VACTERL work up" to identify some of the medical problems they are looking for. "A" is for "anus" and the child has "imperforate anus"

Upon completion of these tests the physician will make the diagnosis. The anatomy may be very complex in children with imperforate anus. For more technical medical information about this condition and related procedures, visit our information on Imperforate Anus for referring physicians.

This information is provided by the University of Michigan Department of Surgery, Section of Pediatric Surgery and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact your health care provider or our offices.