About Anorectal Malformations

Anorectal Malformations in Children

Patient and family education is important to us. Here you can learn more about anorectal malformations in children (such as imperforate anus or cloacal abnormalities) and view trusted insights from KidsHealth.org, the No. 1 most viewed health site for children, created by the experts at Nemours. We've also provided information from the most respected non-profit organizations.

How Anorectal Malformations Affect Children

To better understand anorectal malformations, it’s helpful to know how the body develops and the processes impacted by this condition.

In normal development, babies are born with separate tubes that open to the outside of the body, with each serving its own function.

  • the rectum and anus allow the passage of stool
  • the urethra allows the passage of urine
  • the vagina (in girls) allows sexual intercourse and childbirth

This region in both boys and girls is collectively called the “perineum.”

An anorectal malformation is a defect in the development of the anus and rectum (“ano” refers to the anus, and “rectal” the rectum), that impact the bowel movement process, or how waste (feces, stool or poop) is naturally eliminated from the body.

During a bowel movement:
  • Stool passes through the small and large intestines and the rectum, or the portion of the tract just above the anus (the opening of the large intestine).
  • When stool reaches the anus, nerves in the anal canal sense the need to eliminate the waste.
  • The nerves send messages to activate the muscles that control when the bowels will move.

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When the digestive system isn’t working properly because of an anorectal malformation, it may cause:

  • constipation and discomfort
  • inability to control bowels (fecal incontinence)
  • inability to have a bowel movement
  • chronic infections
  • nutritional issues
Types of Anorectal Malformations
Anorectal malformations refer to a spectrum of defects caused by a:
  • narrow or misplaced anal passage (anal stenosis)
  • membrane, or layer of skin, covering the anus (membranous anal atresia)
  • missing connection between the anus and the rectum (imperforate anus)
  • narrow passage (or fistula) that improperly connects the anus and urogenital tract (urinary tract/reproductive system) without an anal opening (anorectal agenesis)
More specifically, anorectal malformations may include:

Rectoperineal fistula: This is a mild type of anorectal malformation in which the anus is positioned slightly closer to the scrotum in boys, and the vagina in girls. Sometimes the anus is covered with a membrane, or thin layer of skin.

Rectourethral fistula: The most common anorectal malformation in boys, this occurs when the rectum ends in a fistula connected to the urethra instead of the anus.

Rectovesical fistula: This is a rare anorectal malformation that occurs in boys when the rectum ends in a fistula that connects to the bladder (where urine is stored before elimination), instead of the anus.

Rectovestibular fistula: This occurs in girls when the anus is in the improper position and stool passes through a narrow vestibule (or cavity) near the vagina. This is the most common anorectal malformation in girls.

Rectovaginal fistula: This condition occurs in girls when the bowel opens directly into the vagina. This is a very rare anorectal malformation.

Cloaca: This severe anorectal malformation occurs in girls when the three tubes (the vagina, urethra and rectum) are joined together and there is only one opening in the perineum.

Prognosis and Long-Term Outlook

The Impact of Anorectal Malformations

Most children with mild anorectal malformations (like rectoperineal fistulas) regain good control over their bowel movements after repair. Children with more complex anorectal malformations may require ongoing (sometimes lifelong) bowel management and follow-up care to prevent fecal incontinence (lack of control over bowel movements).

In addition to the physical component of this condition, kids with anorectal malformations often have emotional problems that affect self-esteem, social development and the family relationship. A comprehensive treatment plan must address both the physical and mental effects of living with a chronic condition.

Toilet Teaching Your Child

Toilet teaching should begin at the normal age, which is considered anywhere between 18 to 24 months, or later, depending on the child. It may take a little longer for your child to gain control over bowel movements — and, depending on the type of malformation and the repair, there may be chronic constipation or other ongoing bowel issues.

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