Anorectal Malformations

Anorectal malformations are birth defects where the anus (the opening that your stool passes through) and the rectum (the end of the large intestine that leads to the anus) do not develop properly.

Contact our multi-disciplinary clinic at 832-822-3135 for an appointment .

Patients can be seen by Texas Children's experts in Pediatric and Adolescent Gynecology and Pediatric Surgery and Pediatric Urology.

Causes & Risk Factors

Anorectal malformations are congenital disorders, meaning they are present at birth. These malformations occur when the fetus doesn’t develop properly in the womb. In most cases the cause of this abnormal fetal development is not known.

Many babies who have anorectal malformations also have other congenital defects.

Symptoms & Types

With an anorectal malformation, several abnormalities can occur which cause problems when a child has a bowel movement, including:

• The anal passage is too narrow – the baby may have difficulty passing a stool, causing constipation and discomfort
• A membrane (thin layer of tissue) covers the anal opening – the baby may be unable to have a bowel movement
• The rectum is not connected to the anus (this is called an imperforate anus) – stool is unable to leave the intestine, therefore the child is not able to have a bowel movement, causing a blockage in their intestine
• The rectum connects to part of the urinary tract or reproductive system through an abnormal passage called a fistula – stool will leave the baby's body through the fistula instead of the anus, which can lead to infections 

Diagnosis & Tests

When a baby is born a physician performs a physical exam and looks to see if the anus is open or if there are any other signs of malformation.  

Imaging tests may also be done to view the internal organs, including:

• Abdominal x-ray
• Abdominal ultrasound
• CT or CAT scan (computed tomography scan)
• MRI (magnetic resonance imaging)
• Lower GI (gastrointestinal) series (or barium enema) – uses a fluid (barium) to coat the inside of the rectum before an x-ray is taken, to show areas that are narrow or blocked, or other abnormalities
• Upper GI series – a fluid (barium) is swallowed to coat the upper organs of the digestive system before taking an x-ray, for more detailed images

Treatment & Care

Treatment depends on the individual patient and her symptoms; however the majority of infants with an anorectal malformation will need to have surgery to correct the problem.

Treatment strategies include:

• Anal dilatation – to stretch the anal muscles if the anal passage is too narrow, allowing stool to pass through more easily
• Surgery to remove an anal membrane
• Surgery to connect the rectum and anus – typically involves a series of operations performed within the first several months of a baby’s life

Children with complex cases may be slower than others to learn toilet training and may find it difficult to control their bowel movements, requiring special help and care.