Anorectal Malformation in Children: Causes, Symptoms, and Treatment Options

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What is Anorectal Malformation?

Anorectal malformation is a congenital condition in which the anus and rectum (the lower part of the bowel) do not develop properly. This means that the anal opening where bowel motions (poo) normally exits into the toilet / nappy is blocked, misplaced, or absent altogether. The condition is present from birth and can range from mild to severe, depending on how the malformation affects the structure of the bowel and surrounding tissues.

Anorectal malformation is also known as an imperforate anus. It occurs in approximately 1 in 5,000 births and may be associated with other congenital abnormalities, including issues with the urinary system, spine, and other parts of the body.

Types of Anorectal Malformation

The condition can vary significantly in severity. The most common types include:

Rectourethral fistula: In males, the rectum is joined to the urethra (the pipe for passing urine).
Rectovestibular fistula: In females, the rectum is joined just underneath the vaginal opening.
Perineal fistula: The anus is not in a normal position, and closer to the genital area.
Anal stenosis: The anus is very narrow. Sometimes this is called a “funnel anus”.
No Fistula: Rather than a connection between the rectum and other nearby organs, the rectum is blind ending pouch.
Cloaca: A more complex condition seen in females, where the rectum, vagina, and urinary tract share a single opening.

It is often not possible to determine what type your child has immediately. Your paediatric surgeon will determine the type and severity of the malformation during diagnosis and guide you on the best course of treatment.

What Causes Anorectal Malformation?

The exact cause of anorectal malformation is complex, and occurs during early foetal development, usually within the first 8-12 weeks of pregnancy. In most cases, the condition occurs sporadically, meaning it is not passed down from parents.

Some factors that may increase the likelihood of this condition include:

Genetic predisposition: There is some evidence that genetics may play a role.
Associated syndromes: Anorectal malformations are often linked to other congenital abnormalities, such as VACTERL association, which includes defects in the Vertebrae, (Anorectal), Cardiac (heart), Trachea, oEsophagus, Renal (kidneys), and Limbs.

Symptoms of Anorectal Malformation in Infants

Signs of anorectal malformation are often detected shortly after birth. These include:

No visible anus or abnormal position: There is often a pigmented area where the anus should be. The actual opening may not be visible.
Failure to pass meconium within the first 24-48 hours after birth, or severe constipation in later months.
Abnormal stool patterns: Meconium (the first bowel movement) may pass through the vagina, urethra, or perineum if a perineal fistula is present.

If you notice any of these symptoms in your newborn, seek immediate medical attention.

How is Anorectal Malformation Diagnosed?

Diagnosis typically occurs shortly after birth through a physical examination. Further tests may be performed to assess the severity of the condition and identify any associated abnormalities:

Imaging tests: X-rays, ultrasounds, or MRI scans can help determine the anatomy of the pelvis, spine and kidneys.
Contrast studies: A dye may be used to outline the rectum and nearby organs to check for fistulas.
Echocardiogram: To rule out any associated heart defects.

Treatment Options for Anorectal Malformation

Surgery is the main treatment for anorectal malformation. The goal of surgery is to create a functioning anus and ensure proper bowel function and control.

The specific procedure depends on the type and severity of the malformation:

Colostomy: In many cases, a temporary colostomy may be performed shortly after birth to allow stool to pass into a bag on the abdomen. This lets the baby feed and grow while understanding the anatomy before corrective surgery.
Anorectal Reconstruction: This surgery creates an opening in the expected position and connects it to the rectum. It is called anorectoplasty. It can be performed from below or laparoscopically (keyhole) depending on the anatomy of the child.
After the new anal opening has healed (sometimes it requires examination under anaesthesia after reconstruction), the colostomy can be closed and the child will pass bowel movements through the new opening.

Your paediatric surgeon will discuss the surgical options and the expected outcomes with you in detail. This is a long conversation, and may be over a few visits.

Colostomy

Long-Term Outlook for Children with Anorectal Malformation

With appropriate treatment, most children can achieve good bowel movements and lead healthy, active lives. They will need help with keeping the bowel motions under control, and are often slow to toilet train. They often have issues with constipation, and need help with diet and laxatives.

However, the long-term outlook depends on the severity of the malformation and whether other conditions are present.

Follow-up care is crucial to monitor bowel function and address any complications, such as constipation. Your child may also benefit from:

Bowel management programs to help establish regular bowel movements.
Physiotherapy or pelvic floor training for older children.
Psychology to help deal with the issues around multiple conditions, and bowel control