Health Library

Anorectal Malformations / Imperforate Anus

How Often Do Anorectal Malformations Occur?

Anorectal malformations affect about one in every 4,000 babies and happen slightly more often in boys. The exact cause is unknown, and there are no known risk factors that parents can control. Most babies with an ARM do not have a family history of the condition. But there may be a small genetic component. Families who already have one child with an ARM have about a 1% chance of having another child with an ARM, which is higher than the risk in the general population.

What Types of Anorectal Malformations Are There?

Each type of anorectal malformation has its own characteristics, and ARMs affect every child differently. The issues a child may have depend largely on the specific type of ARM and the outcome of surgical treatment.

Below are the most common types of ARMs in children.

Boys

• ARM with recto-perineal fistula: In boys, the perineum is the small area between the scrotum and the anal sphincter. This type of ARM happens when a baby does not have a properly formed anus, and the rectum ends in a tiny opening in the perineum.


• ARM with urinary fistula: This is a category of malformations in which the rectum ends somewhere in the urinary tract. The poop can leak into the urine and may show up as poop staining in the urine, or by finding feces in the urine through a lab test (urinalysis). There are several variations of urinary fistula that are commonly seen:


• ARM with recto-bulbar fistula: In this type of ARM, the rectum connects to the urethra at the level of the lower urethra.


• ARM with recto-prostatic fistula: In this type of ARM, the rectum connects to the urethra at the level of the prostate (upper urethra).


• ARM with recto-bladder neck fistula: In this type of ARM, the rectum and bladder connect in a way that is not normal. The poop can leak into the urinary tract and may be detected by urinalysis. Usually, this opening is not large enough for the poop to fully exit, and the baby’s colon becomes blocked.


• ARM without fistula: In this type of ARM, the rectum ends in a “blind pouch.” The rectum does not connect to anything.

Girls

• ARM with recto-perineal fistula: In girls, the perineum is the small area between the anal sphincter and the labia (female external genitalia). In this type of ARM, the anus does not form in the normal way, and the rectum ends in a tiny opening in the perineum.


• ARM with recto-vestibular fistula: In females, there is a small area between the exterior genital (labia) and the vaginal opening. This is called the vestibule. In this type of ARM, the anus does not form in the normal way, and the rectum ends in a small opening in the vestibule. This type of ARM is often misdiagnosed as a recto-vaginal fistula.


• ARM with recto-vaginal fistula: In this type of ARM, there is a passageway between the rectum and vagina that is not normal. As a result, gas and poop can leak into the vagina. This is a very rare type of ARM. Patients often receive this diagnosis as a mis-label for a recto-vestibular fistula.


• ARM without fistula: In this type of ARM, the rectum ends in a “blind pouch.” The rectum does not connect to anything.


• Cloaca: In this complex type of ARM, the rectum, vagina and urethra join into one common passageway and exit through one opening. Instead of having three passageways in the anorectal area (anus, vagina and urethra) the child has only one.

What Conditions Are Associated with Anorectal Malformations?

Approximately 50% of babies with anorectal malformations also have “associated defects,” sometimes described as “VACTERL association.” This condition is sometimes called VACTERL / VATER syndrome.

VACTERL is an acronym. It stands for vertebral defects, anorectal malformation, cardiac defects, trachea-esophageal fistula, renal anomalies, and limb abnormalities.

• Vertebral defects. These affect the bones of the spinal column and can include spinal abnormalities, such as hemivertebra, absent vertebra, sacral abnormalities and / or tethered spinal cord.


• Anorectal malformation. In girls, this can involve problems with the reproductive system that can affect the vagina, uterus and ovaries. In boys, this can involve problems with the bladder.


• Cardiac defects (congenital heart defects)


• Tracheal-esophageal fistula and disorders. This is a connection between the trachea (the windpipe) and the esophagus (the feeding tube).


• Renal anomalies (kidney malformations, bladder abnormalities and dysfunction, and / or duplication of parts of the urinary tract)


• Limb abnormalities, most commonly affecting the forearm, hand, fingers and toes

Children who have been diagnosed with VACTERL association usually have at least three or more of these anomalies.

Because of these associated defects, it is important for children to receive care from a multidisciplinary team of experts that can evaluate and treat these conditions in a coordinated way.

How Are Anorectal Malformations Diagnosed?

Anorectal malformations are most often diagnosed just after birth during the first exam. Often the doctor notices that the child’s anus is not present or is in the wrong place. Some children are diagnosed during a prenatal ultrasound. When this happens, the doctor may refer families to a maternal-fetal medicine center.

After the diagnosis, more tests are needed to understand the type of anorectal malformation a child has and what type of care is needed.

• Abdominal X-rays show the location of the malformation. They may help determine if the ARM is high or low in the anorectal area. These X-rays also can show associated defects of the spine and sacrum (tailbone).


• Renal ultrasound can show if there is something about the kidney, bladder and urinary tract that is not normal.


• Pelvic ultrasound is used to see how the ARM may affect the reproductive organs in girls.


• Spinal ultrasound can show signs of a tethered spinal cord, where the end of the spinal cord is not attached in the normal way. A tethered spinal cord may cause neurological problems, urinary and fecal incontinence, and leg weakness as the child grows. This test also is used to find any mass in the presacral space (the area between the rectum and the lowest part of the spine). These masses are usually not cancerous.


• Magnetic resonance imaging (MRI) sometimes is needed to make a definite diagnosis of tethered cord or other spinal abnormalities. MRI also is used to view the pelvic muscles and reproductive organs.


• Echocardiogram detects any heart defects.

How Are Anorectal Malformations Treated?

Each child with an anorectal malformation has unique needs. The care team will create a treatment plan based on your child’s type of ARM, the presence and type of associated conditions, and their overall health. Working together, these experts can help your child have the best quality of life possible. Common treatments include:

Posterior Sagittal Anorectoplasty (PSARP)

Children who have an ARM will need surgery called a PSARP to correct the problem. This procedure is often called an anorectoplasty. It involves moving the anus to the location within the muscles (anal sphincter) that control the bowels. This surgery allows gas and poop to leave the body. It may be done soon after birth or later. Timing depends on the child’s needs.

When possible, the surgeon can use laparoscopic or robot-assisted surgical techniques. This can mean less pain, less blood loss and faster healing. There is often a shorter hospital stay. Patients who have an “open” or traditional surgery may have a longer hospital stay.

Colostomy Surgery

Before the PSARP procedure, some children have a colostomy. This surgery involves creating an opening (stoma) in the abdominal wall and bringing a part of the large intestine out through the opening. This creates a way for poop and gas to pass through the body until the PSARP procedure can take place. The surgeon also creates a second opening called a mucous fistula. This helps the team do diagnostic testing before the PSARP. The surgeon will close the colostomy a few months after the PSARP, since it will no longer be needed.

Post-Surgery Care

When recovering from a PSARP, patients have minimal pain. The care team keeps the child comfortable, watches them closely and looks for any signs of infection. Parents can hold and bond with their child during the hospital stay. The surgeon uses stitches that dissolve, so no procedure is needed to remove them.

After surgery, the child may have frequent loose bowel movements / diarrhea. This can cause diaper rash and irritate the skin. Within a few weeks, poops happen less often and are firmer. Even after surgical repair, some children continue to have constipation. The care team will work with you closely to minimize any symptoms. The child may need to follow a high-fiber diet and take laxatives. A few weeks after the PSARP procedure, a post-op clinic visit is scheduled. At this visit, the surgeon will check your child’s progress and talk with you about any concerns.

What is Toilet Training Like for a Child with an Anorectal Malformation?

Children who have an anorectal malformation may gain bowel control more slowly than children who do not have a malformation. Their type of malformation may make them unable to have good bowel control. It is important to talk about this with the care team. They can explain your child’s individual situation.

Toilet training for a child with an ARM should start at the usual age. This is often around 3 to 4 years old. If your child is not in normal underwear when other children their age are, the care team may suggest a bowel management program like the one offered through the Colorectal Center at Cincinnati Children’s. The goal of these programs is to help children gain control of their bowels and bladder by using laxatives and / or enemas and, in some cases, eating a special diet.

What is the Long-Term Outlook for a Child with an Anorectal Malformation?

Children with a less complex anorectal malformation are often able to gain good control over their bowel movements after surgical repair. Those with more complex types of ARMs may need to take part in a bowel management program to prevent constipation and gain control of their bowel movements.

Long-term follow-up care for children with an ARM may include seeing a:

• pediatric urologist
• gynecologist
• gastroenterologist
• dietitian
• physical therapist
• behavioral medicine specialist

Your child’s care team will create a treatment plan tailored to your child's situation. They will adjust this as your child grows.