Anorectal Malformations / Imperforate Anus


What is an anorectal malformation or an imperforate anus?

Anorectal malformation, also known as imperforate anus, is a condition where children are born with an abnormal anal opening. This condition affects 1 in 2,500 children. The causes of this condition are not known for sure, but are likely due to a problems with prenatal development of the digestive tract.

There are different types of anorectal malformation or imperforate anus. Your child can have an anus that’s missing, very narrow, or blocked by a thin membrane. In some cases, your child’s rectum (the lowest part of the intestine) may not connect to the anus. In other cases, your child’s rectum may connect to the urinary tract or genitals instead. This is called a fistula. In girls, the rectum may connect to both the urinary tract and the vagina. This type of anorectal malformation is called a cloacal malformation or cloaca.

What causes anorectal malformations?

Experts aren’t sure what causes this condition, but a problem likely occurs during pregnancy when your child’s digestive tract is developing. Genetics and environmental factors may play a role, but no one cause has been identified.

Sometimes imperforate anus occurs as a part of a syndrome. These syndromes may include problems with other body parts or organ systems. They can include:

  • VACTERL syndrome
  • CHARGE syndrome
  • Currarino syndrome
  • Townes-Brocks syndrome

Your doctors will work together to create a comprehensive care plan customized to address any problems that your child may face.

What are the symptoms of anorectal malformations?

Most anorectal malformations are diagnosed at birth. In some cases, an anus that is too narrow (anal stenosis) or slightly displaced may not be diagnosed until the child is older.

Symptoms may include:

  • Difficulty passing bowel movements
  • Swelling or bloating of the abdomen
  • Constipation
  • Vomiting

How is an anorectal malformation diagnosed?

Your doctor will perform a physical exam, including an anorectal exam, to determine the location of the anus relative to the anal sphincter muscles. This exam may be done in the office or in the operating room. Your doctor may also order additional tests to check for other issues that may be associated with anorectal malformation. These can include:

  • X-ray of the abdomen and pelvis
  • X-ray of the spine and sacrum
  • Ultrasound or MRI of the spine and spinal cord
  • Colostogram, to check bowel anatomy
  • Cystourethrogram, to look at the urinary tract
  • Echocardiography, to look for heart problems

Your child’s healthcare provider will give your child a very detailed checkup. Other issues may be more urgent than the imperforate anus. These problems may need to be treated first.

How are anorectal malformations treated?

Treatment for an anorectal malformation depends on the type of malformation.

In most cases, treatment will begin with an exam under anesthesia. In this procedure, doctors will examine the position of the anus relative to the anal sphincter muscles. Doctors may also examine the urinary tract and/or the genital tract. After this exam, doctors will work with you to customize the best treatment plan based on your child’s unique anatomy.

The type of surgery will depend on your child’s condition. Some children with anorectal malformations may need only one operation, whereas others may need more than one. Some children may need an ostomy to divert the flow of stool until the anus can be safely repaired. Sometimes, other medical issues may need to be addressed before surgery. In each case, the goal of surgery is to place the anal opening in its normal anatomic position within the anal sphincter muscles and to address any urogenital anomalies for the best future function.

What is the long-term care for children with anorectal malformations?

Long-term outcomes may vary depending on the type of anorectal malformation. In most cases, children with anorectal malformations learn how to control their bowel movements at the same age as other children, but some children may have trouble controlling their bowel movements. Bowel management programs can be helpful to achieve continence. Whether the initial surgery was done at Texas Children’s Hospital or elsewhere, we can work with you to find a regimen that works for you and your child.

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