Imperforate Anus

An imperforate anus, also known as an anorectal malformation, is a birth anomaly caused by improper development of the fetal rectum and anus during pregnancy. The opening at the end of the rectum, or anus, is abnormal or absent so the baby cannot stool normally. This malformation typically develops between the fifth and seventh week of gestation. There are several different types of anorectal malformation, and the variant will determine management.


The cause for an imperforate anus remains unknown.


Fetal imperforate anus can sometimes be diagnosed before birth by ultrasound if there is significant dilation of the distal colon. There are no prenatal tests that can be done to definitively determine if a baby has an anorectal malformation. Once a baby is born, they can be diagnosed by a doctor’s physical examination.

As there are often associated anomalies in children with an anorectal malformation, there are several tests done to determine if there are any other conditions exist.

 Some of those tests include:

  • Ultrasound of the kidneys
  • Voiding Cystourethrogram (VCUG)
  • Ultrasound of the spine
  • MRI of the spine
  • Echocardiogram


When a baby has an anorectal malformation, they will have trouble passing bowel movements or may not pass a bowel movement at all within the first 48 hours of their life. This can cause abdominal distension and/or vomiting. In some cases, the baby may stop eating.


A surgical repair is required for a child born with an imperforate anus. The timing of surgery depends on the type of malformation the baby has.

In general, a temporary colostomy procedure is done first. A surgeon will make an incision in the abdomen and then make two openings in the baby’s large intestine. These openings, otherwise known as a colostomy and mucous fistula, are sutured to the skin. Stool comes out of the stoma and into a bag that is attached to the outside of the baby. Our team is staffed with specialized advance practice registered nurses (APRN) who will teach the parent how to take care of the stoma at home during this time period.

Once the baby has grown to a certain size and weight, surgery will be done to create a new anus.  This is considered a “pull-through” operation or sometimes referred to as a “PSARP”. A surgeon pulls the rectum down to connect it to the new “neo-anus”. After this procedure, the neo-anus will require dilations at home and in the office to help it heal and be ready to start to accommodate stool. Once the neo-anus has healed and is deemed large enough, the colostomy will be closed and stool will now come through the neo-anus.   

Postoperative Course

After each surgery, your child will remain in the hospital for a few days (length of stay varies on the child and the procedure performed) to allow time to recover and heal properly. Your child will receive pain management and hydration through an I.V. (special thin, plastic tube that stays in the blood vessel). They may also have a small tube in their nose that ends in their stomach.

Once the child’s intestines resume normal function (they are able to pass gas and stool on their own), the tube will be removed from their nose and they will be allowed to eat. When they are able to tolerate their feedings by mouth, the I.V. will be removed and they can go home.

If your child has an ostomy, one of the APRNs from the wound/ostomy team will meet with you in the hospital to develop a plan for at-home care.

If your child does not have an ostomy, then you will be given a skin care regimen to assist with their diaper rash. In the first few weeks after the colostomy is closed and stool comes through the neo-anus, expect that your child may have 8-12 stools per day initially. Over time, the number of stools will likely decrease although the exact number of stools depends on the child.

Home Care

Your child will still be recovering even after they are home. You will monitor the amount of food or formula that they are taking; keeping your child hydrated will be essential in recovery. Also, they may still need to take some medications. You will need to maintain good skin care in the diaper area or around the ostomy to prevent skin breakdown. If your child has an ostomy, you will be provided with appropriate supplies to care for this area. Once you are home, supplies will be ordered through a homecare company and delivered to your house.

After each operation, your child will have a follow-up appointment with your surgeon and APRN one to two weeks after discharge. At these visits, the stoma will be examined, incisions checked and weight monitored. When appropriate, the parent may learn how to perform dilations of the new anus. Dilations are done with a simple instrument (similar to a rectal thermometer) that will prevent the site from narrowing during the healing process. This procedure may need to be done at home two times a day by the parents.

Once your child has fully recovered from surgery, they will be followed on a routine basis by your surgeon and the APRN group to ensure adequate weight gain and optimal outcome.

Long-term Care

Your child will need to learn proper bowel management skills to ensure they live a healthy, normal lifestyle. 

Children with anorectal malformations are followed in our Colorectal Center. This multidisciplinary clinic uses various approaches to help children who have colorectal conditions (including anorectal malformations) that have required surgical interventions to manage constipation and achieve continence. Our goal is for our patients to participate in all social activities, with the confidence of being accident-free.

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