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Anorectal Malformation

What is an anorectal malformation?

Anorectal malformations are birth defects, or problems that happen as an unborn baby is developing during pregnancy. With this defect, the anus and rectum don’t develop properly. They are the lower part of the digestive tract.

  • Ano means the anus. This is the opening at the end of the large intestine. Stool passes through here when there is a bowel movement.
  • Rectal means the rectum. This is the part of the large intestine just above the anus.

Normally during a bowel movement, stool passes from the large intestine to the rectum and then to the anus. Muscles in the anal area help to control when you have a bowel movement. Nerves in the area help the muscles sense the need for a bowel movement. The nerves also stimulate muscle activity.

With an anorectal malformation, several problems can occur. These include:

  • The anal passage may be narrow
  • The anal opening may be covered with a tissue or membrane
  • The rectum may not connect to the anus
  • The rectum may connect to part of the urinary tract or the reproductive system. This happens through a passage called a fistula.

Anorectal malformations cause problems with how a child has a bowel movement. Treatment depends on which type of problem your baby has.

What causes an anorectal malformation?

As an unborn baby is growing in its mother's womb or uterus, different organ systems are developing and maturing. The lower end of the intestinal tract forms fairly early in pregnancy.

In an unborn baby, the lower part of the large intestine and the urinary tract start off as one large mass of cells. Certain steps must happen in the first 3 months of pregnancy or gestation. These steps are needed for the rectum and anus to break away from the urinary tract and form properly. Sometimes these steps don’t happen as they should. Then the rectum or anus may not develop normally. In most cases, it’s not known what causes this to happen.

Who is at risk for an anorectal malformation?

Anorectal malformation may be seen with some genetic syndromes or congenital problems that are present at birth. These include:

  • VACTERL association. This disorder includes problems with the spine, anus, heart, trachea, esophagus, kidneys, and arms and legs.
  • Digestive system problems
  • Urinary tract problems
  • Spinal problems
  • Down syndrome
  • Townes-Brocks syndrome. This syndrome includes problems with the anus, kidneys, ears, and arms and legs.

What are the symptoms of an anorectal malformation?

Anorectal malformations cause problems with how a child has a bowel movement. Most anorectal malformations are found before a newborn leaves the hospital. If the problem is not found in the hospital, symptoms may include:

  • Lack of stool
  • Stool coming from the vagina
  • Urine coming from the anus
  • Trouble having a bowel movement, or constipation

How is an anorectal malformation diagnosed?

Your child's healthcare provider will do a physical exam when your baby is born. The provider will look at your child’s anus to see if it is open. Your child may also have imaging tests such as:

  • Abdominal X-rays. This test makes images of internal tissues, bones, and organs.
  • Abdominal ultrasound. This test uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to see internal organs and to check blood flow through different vessels.
  • CT scan. This test uses X-rays and a computer to make images of any part of the body. This includes the bones, muscles, fat, and organs. A CT scan is more detailed than a general X-ray. Older children may have a general X-ray.
  • MRI. This test uses a magnetic field and radio waves to make detailed images of organs and structures in the body. Older children may have this test.
  • Lower GI or gastrointestinal series, also called a barium enema. This test checks the rectum, the large intestine, and the lower part of the small intestine. A metallic, chalky fluid called barium is put into the rectum as an enema. It coats the inside of organs so that they will show up on an X-ray. An X-ray of the belly or abdomen shows narrowed areas called strictures, blockages, and other problems.
  • Upper GI or gastrointestinal series, also called barium swallow. This test checks the organs of the upper part of the digestive system. That includes the food pipe or esophagus, the stomach, and the first section of the small intestine, called the duodenum. A metallic, chalky fluid called barium is swallowed. It coats the inside of organs so that they will show up on an X-ray. Then X-rays are taken to check the digestive organs.

How is an anorectal malformation treated?

Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how severe the condition is.

Most babies with anorectal malformation will need to have surgery to correct the problem. The type and number of surgeries your child needs will vary. It depends on the type of problem your child has. These problems include the following:

Narrow anal passage

Surgery may not be needed. A procedure known as anal dilation may be done from time to time. This helps to stretch the anal muscles so stool can pass through.

Anal membrane

Surgery is done to remove the membrane. Anal dilations may need to be done to help with any narrowing of the anal passage.

Lack of rectal or anal connection, with or without a fistula

A series of surgeries is done to repair the problem. These surgeries include:

  • Colostomy. With a colostomy, the large intestine is divided into 2 sections. The ends of the intestine are brought through openings in the stomach. The upper section lets stool pass through the opening (stoma) and into a collection bag. The lower section lets mucus made by the intestine pass into a collection bag. A colostomy does not damage your child's digestion. Your child can also grow before the next surgery is needed. And when the next surgery is done on the lower section of the intestine, there won’t be any stool there to infect the area. The nursing staff and other healthcare professionals that work with your child's surgeon can help you learn to take care of the colostomy. Local and national support groups may also be helpful.
  • Attaching the rectum to the anus. This surgery is often done in the first few months of life. The colostomies stay in place for a few months after this surgery. This is so the area can heal without being infected by stool. The rectum and anus are now joined. But stool will leave the body through the colostomies until they are closed with surgery. A few weeks after surgery, you may be doing anal dilations to help your child get ready for the next phase.
  • Closing the colostomies.  This surgery is done about 2 to 3 months later. Your child will not be able to eat anything for a few days after surgery. This lets the intestine heal. Several days after surgery, your child will start passing stools through the rectum. At first, stools will pass often and they will be loose. Diaper rash and skin irritation can be a problem at this stage. A few weeks after surgery, the stools happen less often and are more solid. This often causes constipation. Your child's healthcare provider may recommend a high-fiber diet to help with constipation. This includes fruits, vegetables, juices, whole-wheat grains and cereals, and beans.

You can start toilet training at the usual age, when your child is between 2 and 3 years old. But a child who has had an anorectal malformation repaired may be slower than others to gain bowel control. Your child may not have good control over bowel movements. Or your child may have long-term (chronic) constipation. This depends on the type of malformation and its repair. Your child's healthcare provider can explain the outlook for your child.

What are the complications of an anorectal malformation?

An anorectal malformation can cause problems in the way your child has a bowel movement. These problems will vary depending on the type of malformation your child has. These include:

  • Narrow anal passage. Your child may have trouble passing a bowel movement. This causes constipation and possibly mild pain.
  • Membrane over the anal opening. Your baby may be unable to have a bowel movement.
  • Rectum is not connected to the anus, but there is a fistula. Stool will leave your baby's body through the fistula instead of the anus. This can cause infections.
  • Rectum is not connected to the anus, and there is no fistula. There is no way for stool to leave the intestine. Your baby will be unable to have a bowel movement. If this is not treated, it can be fatal.

Living with an anorectal malformation

Sometimes children are able to gain good control over their bowel movements after the problem is repaired. This is often the case for children with an anal membrane or a narrow anal passage.

If your child has a more complex type of anorectal malformation, he or she may need to take part in a bowel management program. This can help your child have control bowel movements and prevent constipation. The nurses and other healthcare professionals who work with your child's provider can help create a program for your child.

When should I call my child's healthcare provider?

Call your child’s healthcare provider right away if an anorectal malformation was not found in the hospital but your child:

  • Passes stool from her vagina
  • Passes urine from the anus
  • Has constipation

If your baby does not pass stool, it is a medical emergency. You should seek medical care right away.

Key points about anorectal malformations

  • Anorectal malformations are birth defects. The anus and rectum do not develop properly.
  • An anorectal malformation causes problems with how a child has a bowel movement.  
  • Most babies with this problem will need surgery to correct it.
  • Depending on the type of malformation, your child may have good control of bowel movements after the problem is repaired.
  • If your child can’t control his or her bowel movements, a bowel management program can be very helpful.

Next steps

Tips to help you get the most from a visit to your child’s healthcare provider:

  • Know the reason for the visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
  • Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
  • Ask if your child’s condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if your child does not take the medicine or have the test or procedure.
  • If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.
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