Anorectal Malformations

The term anorectal malformations (ARM) encompasses a wide range of congenital anomalies resulting in the abnormal position of the anus, and potentially other associated conditions. These areas include the anus, rectum, lower spinal cord, and the genitourinary tract. There are many variations that can occur with ARM. 

Types of Anorectal Malformations

One type of ARM is known as cloaca. This type of ARM occurs in girls who have one common channel for the urethra, anus and vagina, which are normally three separate channels.

Another type of ARM is known as cloacal exstrophy, which occurs in boys and girls. It is always associated with an omphalocele and the two halves of the bladder and intestines are open on the outside of the lower abdomen.

ARM can also be referred to as imperforate anus, which 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. 

For some children, ARM is a part of a condition known as VACTERL or VATER. These are syndromes in which the child has three or more body systems that are affected. The areas of the body that can be included in this diagnosis are the Vertebrae/Spine, the Anus/rectum, Cardiac, TracheoEsophageal fistula-Esophageal Atresia, Renal (kidneys), and Limbs.

Occurrence Rate & Risks of Anorectal Malformations

Approximately 1 in 5,000 children are born with an anorectal malformation. These conditions affect boys more than girls. During the seventh to tenth week of gestation, the rectum and anus separate from the urinary tract. Sometimes, these steps do not occur as they should, and the rectum, anus and/or genitourinary structures may not develop normally. There are no known causes. The type of malformation is unique to each child.

There are no prenatal tests to discover most ARM. In the case of cloacal extrophy, the condition can be discovered with a level II ultrasound. Mothers and babies with associated spinal cord abnormalities may also have an abnormally elevated AFP. In some babies with a cloaca, the diagnosis can be suspected on a prenatal ultrasound.

Autosomal recessive inheritance has been observed rarely in some studies. This means that each parent unknowingly carries a gene for the condition, and the child receives both copies of the gene. Couples who are gene carriers have a 25% chance for the malformation to reoccur in a future pregnancy. About one-third of children who have genetic syndromes, chromosomal abnormalities, or other congenital defects also have ARM.

Diagnosis of Anorectal Malformations

A physical exam by the physician is performed to evaluate the anal opening. Some physical findings of ARM include:

  • Membrane covering the anal opening
  • The anal opening is not in the correct area
  • There is no anal opening and stool may be discovered in the urine or noted to be coming from the vaginal opening

An exam under anesthesia may need to be performed to determine if the anal opening is in the correct spot. Based on the findings, diagnostic imaging may be done to further evaluate the patient. The tests are done to determine if there are any additional conditions that may be found in children with ARM.

Listed below are some of the tests that may be done as part of their evaluation:

  • Ultrasound of the kidneys
  • VCUG
  • Ultrasound of the spine
  • MRI of the spine
  • Upper GI
  • Echocardiogram

Treatment of Anorectal Malformations

The treatment for ARM depends on the type of abnormality. Some factors that are considered when making a plan include:

  • The age and size of the child
  • The type of the condition
  • The overall health of the child and his/her medical history
  • The opinion of the physicians involved in your child's care
  • Other organs that may be involved

Surgery for Anorectal Malformations

Patients found to have ARM will need surgery to create an anal opening in the correct place. The most common procedure used to correct imperforate anus is called a posterior sagittal anorectoplasty (PSARP). A series of surgeries may need to be for the best outcome.

In some babies, a temporary colostomy may be necessary. Our team is staffed with specialized advance practice nurses (APN) who will teach the parent how to take care of the stoma at home during this time period. Once the stoma is no longer needed, another surgery will be done to remove the stoma and reconnect the intestines. After this procedure, the stool will then flow from the mouth to the newly created anal opening.

Postoperative Course

After surgery, your child will remain in the hospital for a few days (length of stay varies on the child) 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, pass stool on their own, and have no fevers, the I.V. will be removed and they can go home with you.

If your child has an ostomy, one of the APNs 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 postoperatively, expect that your child will have 8-12 stools per day initially. Over time, the number of stools per day will lessen to 3-4 times per day.

Home Care

Your child will still be recovering even after they’ve been taken 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 you 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.

Your child will have a follow-up appointment with your surgeon and APN one to two weeks after discharge. At this visit, 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 will 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 APN group to ensure adequate weight gain and optimal outcome.

Post Recovery

Most children with ARM will have good long-term outcomes. They should continue to grow and develop normally, however children with ARM may have loose stools or hard stools that are difficult to pass. A good daily bowel management plan will help your child manage these issues. The surgeon and APN group will continue to monitor their growth at their routine follow-up appointments. Our team is committed to following and monitoring these patients through childhood to provide the best care and outcome.

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