Anorectal Malformations/Imperforate Anus :: Nationwide Children's Hospital

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Imperforate Anus or Anorectal Malformation

Imperforate anus, also called anorectal malformation, is a congenital (existing before birth) defect that happens early in pregnancy, while a baby is still developing.

With this defect, the baby’s anal opening (where stool exits), the rectum (the last part of the large intestine), and nerves that tell the body when it’s “time to go” do not develop properly, preventing the child from being able to have normal bowel movements.

In a baby with imperforate anus/anorectal malformation, any of the following can happen:

  • The anal opening may be too small or in the incorrect location – which can cause painful bowel movements or severe constipation.
  • The anal opening may be absent and the small intestine or rectum enters other parts of the pelvic area, like the bladder or vagina, which can lead to chronic infections or bowel obstruction (a dangerous condition where stool becomes trapped inside the body).
  • The anal opening may be absent and the rectum, reproductive system, and urologic system form a single channel called a cloaca, where both urine and stool are passed. This can also lead to chronic infections.

Symptoms and Diagnosis

At birth, doctors will always check to make sure that a newborn baby’s anus is open and in the correct position. Newborns pass their first stool within 48 hours of birth, so internal malformations will usually be detected quickly.  If an issue is found, the doctor will do a number of tests to better understand the problems and to develop a long-term plan for the best outcome. These tests might include:

  • X-rays of the stomach area to show how far the rectum reaches, and to see if there are any problems with the way the lower backbone has developed.
  • Abdominal ultrasound to give the doctor a better look at the urinary tract, and to see if the kidneys are blocked, or if there is other abnormal fluid build-up.  
  • Spinal ultrasound to look at the spine for a tethered cord, which can cause neurological problems, such as incontinence and leg weakness as the child grows.  If this ultrasound shows any abnormalities, usually a spinal MRI is needed.
  • Echocardiogram  to find heart defects.

Treatment

These malformations will always require specialized types of surgical repair, but the exact procedure will depend on the type and severity of the defect, if there are any associated health conditions (see below), and the child's overall health. Even though corrective surgery may restore some function, important nerves and muscles that tell your child when the rectum is full of stool and help keep the contents inside may be missing or damaged, so starting a bowel management program when they reach toilet-training age may help them become clean.

Toilet Training

Toilet training can be started at the usual age, around three years old. Children who have had imperforate anus generally gain bowel control more slowly. Depending on the type of malformation and the operations done to repair it, some children have difficulty maintaining good bowel control, and may need to participate in a bowel management program. Each child’s situation will be slightly different and will be determined with the help of your child’s healthcare team.

Long-Term Outlook

Children who had a malformation called a rectoperineal fistula as well as those with rectobulbar fistula and rectovestibular fistula are usually able to gain good control over their bowel movements after surgical repair, provided they can avoid constipation.

However, those with more difficult types of anorectal malformation, such as rectoprostatic fistula, rectobladderneck fistula, and cloaca may need to participate in a bowel management program to help them achieve control over their bowel movements and remain clean.

Risk Factors

The condition affects one in 5,000 babies, and it is slightly more common in males than in females. No one knows why some babies are born this way, but in some cases, there is a family history.

Associated Disorders

Almost 50 percent of patients with imperforate anus/anorectal malformations have other defects, including:

  • Spinal malformations
  • Kidney and urinary tract malformations
  • Congenital heart defects
  • Defects in the trachea (windpipe): tracheomalacia or esophagus (the tube that connects the mouth to the stomach): Esophageal atresia
  • Missing arm bones, having an extra finger or toe, thumb abnormalities
  • Other defects in the digestive tract
  • Down’s syndrome

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