Pediatric Anorectal Malformation (Imperforate Anus)

Anorectal malformations (imperforate anus) are birth defects that result in abnormal development of the anus and rectum. In these defects, the anus can be absent, narrowed and/or abnormally connected to the urinary tract.


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What is a Pediatric Anorectal Malformation (Imperforate Anus)?

A pediatric anorectal malformation (ARM) or imperforate anus occurs when a baby’s anus and rectum do not form correctly. These malformations occur while a baby is still developing in the mother’s womb and can affect both boys and girls. However, male infants are more likely to be affected.

Anorectal malformations are discovered during physical exams of the baby. Various imaging tests, including X-rays of the abdomen and spine and ultrasounds, can help the doctor understand what problems exist. These types of birth defects can be difficult to diagnose with precision because some problems occur deep inside the pelvis and are hard to see even with technology. Some children also have other disorders that complicate matters. These disorders can include problems in the formation of the spine and congenital heart defects.

What are the different types of a Pediatric Anorectal Malformation (Imperforate Anus)?

There are several types of anorectal malformations, including:

  • Narrow anal passages
  • The rectum does not connect to the anus
  • Imperforate anus
  • Cloacal Anomaly

What are the signs and symptoms of a Pediatric Anorectal Malformation (Imperforate Anus)?

In newborns, anorectal malformations cause an infant to have difficulty having a bowel movement. In older toddlers, symptoms may include bloating, difficulty or inability to have a bowel movement, and fever. 

How is Pediatric Anorectal Malformation (Imperforate Anus) diagnosed?

Some infants who have anorectal malformations have other birth defects such as congenital heart defects, spinal abnormalities or kidney and urinary tract malformations. Females with an imperforate anus often have an anal opening near their vaginal opening.

If an infant fails to pass a stool within 48 hours of birth, has a distended abdomen or you notice a missing or malformed anus upon an infant’s initial physical examination, the infant should be evaluated immediately to determine the diagnosis. The type and severity of anorectal malformation also determines treatment. In abnormal connections and blockages, the infant will not be able to pass stool.

Because an imperforate anus often is associated with other congenital abnormalities, a specialist in pediatric critical care should evaluate all infants with suspected anorectal malformations for possible co-morbidities such as congenital heart defects or malformations of the spine and urogenital organs.

What are the causes of a Pediatric Anorectal Malformation (Imperforate Anus)?

In a fetus, certain steps have to take place in the 7th to 10th weeks of gestation for the rectum and anus to develop and separate properly from the urinary tract. Anorectal malformations occur in about 1 in 5000 live births.

Abnormal fetal development causes imperforate anus and often occurs along with other birth defects.

How is a Pediatric Anorectal Malformation (Imperforate Anus) treated?

Anorectal malformations require surgery. Surgeons will decide exactly which type of procedures to perform; often more than one surgery is needed to repair every existing problem completely. The first step for newborns who have an imperforate anus and no fistula is a colostomy. Once our experienced surgeons have created a way for the infant’s stool to collect and leave the child’s body through a temporary stoma, they will develop a more permanent plan for creating an anal opening.

Pediatric Anorectal Malformation (Imperforate Anus) Doctors and Providers