Imperforate Anus

An imperforate anus is a defect (something which is abnormal) that happens to an unborn baby while it is still growing inside its mother. The baby develops this defect or abnormality during the fifth to seventh weeks of the mother’s pregnancy.

With these defects, the anus (opening at the end of the large intestine where stool passes) and the rectum (area of the large intestine just above the anus) do not develop properly.

Imperforate anus affects one in 5,000 babies and is a little more common in males.

No one knows the exact reason some baby’s have imperforate anus. The exact cause of imperforate anus is unknown. In some cases, environmental factors or drug use during pregnancy may play a role, but no one is completely sure.

During a bowel movement, stool passes from the large intestine to the rectum and then to the anus. Nerves in the anus help us feel the need for a bowel movement and start muscle activity. Muscles in this area help control when we have a bowel movement.

With an imperforate anus, any of the following can happen:

  • The anal opening may be narrow or misplaced in front of where it should be located.
  • A membrane (covering) may be present over the anal opening.
  • The rectum may not connect to the anus.
  • The rectum may connect to part of the urinary tract or the reproductive system through an opening called a fistula, and an anal opening is not present.

A number of problems can happen depending on the type and how severe the imperforate anus is.

  • When the anal opening is narrow or misplaced in front of the correct location, a child may have a hard time passing a bowel movement, causing constipation and discomfort.
  • If there is a membrane covering the anal opening, the baby may be unable to have a bowel movement until the membrane is opened with surgery.
  • If the rectum is not connected to the anus and no fistula (abnormal connection between the rectum and urinary tract or vagina) is present, there is no way for stool to leave the intestine. The baby will be unable to have a bowel movement. This will cause a bowel obstruction (stool becomes trapped inside the baby).
  • When the rectum is not connected to the anus but a fistula is present, stool may pass through the fistula instead of the anus. This can cause urinary tract infection.

Although most babies who have imperforate anus are the only ones in their family to have it, there are some cases where other family members have had it as well.

Almost 50 percent of babies with imperforate anus have other abnormal defects along with the imperforate anus. These commonly include:

When a baby is born, the doctor will check the baby for any problems. While the doctor is checking the baby, he or she will check to make sure the baby’s anus is open and in the correct position. If an imperforate anus is found, a number of tests may be done to better understand the problem and to see if any other problems are present.

  • X-rays of the stomach will give the doctor a picture showing the general location of the imperforate anus. X-rays also let doctors know if there are problems with the spine and sacrum (a triangle-shaped bone just below the lumbar vertebrae).
  • Abdominal ultrasound and spinal ultrasound -- These tests are used to look at the urinary tract and spinal column. They also help doctors decide if a tethered spinal cord (an abnormality where the end of the spinal cord is abnormally anchored) is present. A tethered spinal cord may cause neurological problems, such as incontinence (toileting without control) and leg weakness as the child grows.
  • Echocardiogram -- This test is done to find heart defects.
  • Magnetic resonance imaging / MRI -- In some cases, this test is needed to make a definite diagnosis of tethered cord or other spinal problems.

Treatment recommendations will depend on the type of imperforate anus, the presence and type of associated abnormalities and the child's overall health. However, most infants with an imperforate anus will need surgery.

Rectoperineal Malformation

Infants with a rectoperineal malformation will need an operation called an anoplasty, which involves moving the anus to an appropriate place within the muscles that control continence (controlled toileting, in this case bowel movements).

Colostomy for Infants with Imperforate Anus Without a Fistula

Newborn boys and girls who have an imperforate anus without a fistula will need one or more operations to correct it. An operation to make a colostomy is usually done early.

With a colostomy, the large intestine is divided into two sections, and the ends of intestine are brought through small openings in the abdominal wall (small opening will be on your child’s belly).

The upper section allows stool to pass through the opening, called a stoma, and into a collection bag. Mucus from the intestine exits through the opening of the lower section of intestine.

By performing this surgery, digestion will not be harmed and growth can continue to happen before the next operation is needed. By changing the original route of the stool, the risk of infection will be smaller when the next operation is done.

Nurses and other healthcare workers who work with your child's doctor will help you learn how to take care of the colostomy, and they will help you as you prepare to take care of your child at home. Local and national support groups may also be very helpful during this time.

The next operation creates a connection between the rectum and the newly created anal opening. This procedure is usually performed from the child’s bottom.

In some cases where the rectum ends within the abdomen (high lesions), laparoscopic surgery (surgery through small holes, usually without an incision) or traditional open surgery (surgery with an incision or cut opening) can be used to bring the rectum down to the anal opening.

After the rectum is brought down to the anal opening the colostomy will stay in place for six to eight weeks. Stool will continue to leave the body through the colostomy until it is closed with surgery. The colostomy will have to stay in place to let the new anal opening heal without being infected by stool and let the child undergo the dilation process (schedule that includes slowly stretching the anus to the correct size for the child’s age).

A few weeks after surgery, parents are taught to perform anal dilatations to make sure the anal opening is large enough to allow normal passage of stool.

The colostomy is closed in another operation at least six to eight weeks later. Several days after surgery, the child will begin passing stools through the rectum (anal opening). Shortly after surgery, stools may be loose and happen more often than usual. Diaper rash and skin irritation can also be a problem. Your doctor and nurse will help you with the care needed to keep the diaper area healthy.

Within a few weeks after surgery, stools will happen less often and become firmer. Anal dilatations should continue for several weeks or months.

Some infants may become constipated. To avoid this, we encourage following a high-fiber diet. Laxatives may be required prior to the age of potty training.

In cases of severe constipation, a bowel management program may be developed according to the specific needs of the child. The program may include child and parent education in the use of laxatives, stool softeners, enemas, bowel training technique.

Toilet training should be started at the usual age, usually when the child is around 3 years old. Children who have had imperforate anus generally gain bowel control more slowly, and depending on the type of malformation and the operations done to repair it, some children may not be able to gain good bowel control. Each child’s situation will be slightly different and will be determined with the help of your doctor.

Children who have had an imperforate anus that have a rectoperineal fistula are usually able to gain good control over their bowel movements after surgical repair.

However, those with more difficult types of anorectal malformation may need to participate in a bowel management program to help them achieve control over their bowel movements and prevent constipation.

Nurses and other healthcare professionals who work with your child's doctors can outline a program made for your child's individual needs.


Last Updated 12/2013