Anorectal Malformation

April 27, 2023 By Dr. Ashish Prasad

Anorectal Malformation

Anorectal Malformation/Imperforate Anus/Absent Anal Opening

Imperforate anus or absent anal opening, also called Anorectal malformation, is a birth defect that happens during the development of baby in early in pregnancy, when the baby is still developing. In this defect, the baby’s anal opening (where stool exits) and the rectum (the last part of the large intestine), do not develop properly, preventing the child from to pass stool.


The condition affects one in 5,000 babies, and it is slightly more common in males than in females. In a baby with anorectal malformation, any of the following can happen:

  • The anal opening is too small or in the incorrect location
  • The anal opening is absent and the rectum enters other parts like urethra, the bladder, vestibule or vagina, which can lead to infections and bowel obstruction.
  • The anal opening may be absent and the rectum, reproductive system, and urologic system form a single common opening called a cloaca, where both urine and stool are passed.

At birth, doctors check the position and size of anal opening.New-borns pass their first stool within 48 hours of birth, so internal malformations are detected quickly. If an issue is found, we do a number of tests to better understand the problems and develop a long-term plan for the best outcome. This problem can be associated with other malformations. Various tests which are performed include:

  • X-rays of the abdomen to show how far the rectal gas reaches, and to see if there are any problems with the way the lower backbone has developed.
  • Abdominal ultrasound to find any problems in kidney.
  • Spinal ultrasound or MRI to look at the spine for a tethered spinal cord, which can cause neurological problems, such as incontinence and leg weakness as the child grows.
  • Echocardiogram to find heart defects.

These malformations will always require surgical repairby a Paediatric surgeon in single or multiple stage.

  • The exact procedure will depend on:
  • the type and severity of the defect,
  • any associated health conditions, and the child's overall health.

Depending on the type and severity these babies may require a stoma formation (a temporary diversion of stools from abdominal wall). The definitive surgery is usually performed at the age of 3-6 months.

Some of these patients can have continence related issues and might require long term bowel management programme.