Imperforate anus

When your baby is born with an imperforate anus, it means their anus is missing or blocked, or their rectum opens into the wrong place in their body. Imperforate anus – also known as an anorectal malformation – is a congenital condition, which means it forms during pregnancy.

The anus is a ring of muscle that lets you hold stool (poop) inside your body and release it during a bowel movement. The rectum is the last section of the gastrointestinal tract, and it normally connects to the anus.

Our experts in fetal and newborn care will guide you through the necessary care your baby will need for this potentially life-threatening condition.

What causes imperforate anus?

The cause of imperforate anus is unknown. It’s thought to occur in the early weeks of fetal development.

What happens if a baby has an imperforate anus?

If your baby has an imperforate anus, there may be no way for stool to exit their body, or their stool may exit through their urethra, vagina or an abnormal opening near where the anus usually forms.

Types of anal malformation

There are several types of imperforate anus, including:

• Anal atresia: Occurs when there is no anal opening and the rectum ends within the abdomen. Stool gets trapped in your baby’s body.
• Rectoperineal fistula: Abnormal opening (fistula) forms between the rectum and the area of skin behind the genitals (perineum). Stool exits through this opening.
• Rectovaginal fistula: In girls, an abnormal opening forms between the rectum and the vagina. Stool exits through the vagina.
• Cloacal malformation: In girls, a single abnormal opening (cloaca) forms that connects the rectum, vagina and urethra (tube that allows urine to leave the body). Both urine and stool exit through the cloaca. This condition creates a large risk of infection.
• Rectourethral fistula: In boys, an abnormal opening forms between the rectum and the urethra. Both urine and stool exit through the urethra’s opening.

Symptoms of imperforate anus

Some symptoms of imperforate anus are:

• Anal opening that’s missing, narrowed or in an abnormal place
• Visible swelling of the abdomen
• First stool isn’t passed within 24 to 48 hours
• Stool exits through the vagina, penis or urethra
• Vomiting

Complications from imperforate anus

Identifying imperforate anus as soon as possible helps prevent complications such as an intestinal obstruction which can lead to a perforation (hole) in the colon or serious infections.

Some people who’ve had imperforate anus corrected surgically may have later complications such as:

• Constipation
• Bowel or bladder control problems, particularly when there are missing or damaged nerves
• Sexual function problems

Diagnosis of imperforate anus

Imperforate anus may be diagnosed during an ultrasound exam performed during pregnancy, because it’s one of the things your doctor monitors.

Diagnosis of imperforate anus at birth starts when newborns are evaluated soon after birth. Your baby’s doctor examines the anus during their first physical exam. Babies are also monitored to make sure they have normal bowel movements during the first 24 to 48 hours after birth.

When an imperforate anus is suspected, your baby may have one or more of these imaging tests:

• X-ray to check rectum size and how the lower backbone is formed
• Ultrasound to check for excess fluids in the kidneys and urinary tract
• Ultrasound to check the spinal cord and its nerves
• Echocardiogram to look for heart defects

Your baby will also be evaluated for other congenital defects. About half of babies born with congenital imperforate anus have other birth defects that may affect the spine, heart, trachea, esophagus, kidneys, urethra, limbs or reproductive organs. If other congenital defects are found, your child’s care team will prioritize treatment for the most important conditions.

Imperforate anus treatment

When your baby is diagnosed with an imperforate anus, they’ll likely have surgery soon after birth to install a colostomy. A colostomy involves making an opening in your baby’s abdomen (belly) that’s connected to their colon. Stool is then allowed to flow into a bag, which is emptied regularly for hygiene and comfort.

Other treatments that may happen soon after birth are:

• Using a tube through your baby’s nose to keep their stomach empty
• Giving your baby intravenous (IV) fluid

Most babies will need to have surgery to correct their anorectal malformation. Your baby’s doctor will rely on the results of their physical exam and imaging tests to decide what kind of surgery to perform.

For some cases, a single surgery will correct the defect. Most often, multiple surgeries are needed to gradually attach the rectum to the anus. The surgeon will also repair any abnormal openings between the intestinal tract and other body parts such as the vagina, penis or urethra.

When multiple surgeries are needed, your child will need a colostomy bag until all the surgeries have healed.

Long-term consequences of imperforate anus treatment

Although some children end up with normal bowel function, your child may need a bowel management program for the rest of their life. If they have malformations of their urinary tract, they may also have trouble with urination. They’ll need to be careful about diet and may need medications to help manage constipation or incontinence.

Your child’s care team, including their primary care doctor, gastroenterologist and other specialists, will work with you to manage follow-up care to maintain good quality of life.