Anorectal Malformation Symptoms & Causes

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What causes an anorectal malformation?

As a fetus is growing in its mother's uterus, all organ systems are developing and maturing at different rates. Certain steps have to take place in the seventh to tenth weeks of gestation for the rectum and anus to separate from the urinary tract and form properly.

  • Sometimes, these steps do not occur as they should, and the rectum and/or anus may not develop normally.

  • Most of the time, the cause for an anorectal malformation is unknown, but in rare cases, a genetic pattern has been seen.

  • Nothing that the mother did during pregnancy can be shown to have caused the malformation.

Are they associated with other problems?

Up to one third of babies who have genetic syndromes, chromosomal abnormalities, or other congenital defects also have anorectal malformations.

Anorectal malformation may be seen with some of these genetic syndromes or other congenital problems:

  • VACTERL association (a syndrome in which there are Vertebral, Anal, Cardiac, Tracheal, Esophageal, Renal, and Limb abnormalities)
  • digestive system abnormalities
  • urinary tract abnormalities
  • abnormalities of the spine

How often do they occur?

Anorectal malformations occur in about 1 in 5,000 babies. Boys are at a slightly higher risk for this abnormality than girls.

What does it mean if my baby has an anorectal malformation?

Anorectal malformations cause abnormalities in the way a baby has a bowel movement.

These problems will vary depending on the type of malformation.

  • If the anal passage is narrow, your baby may have a difficult time passing a stool, causing constipation and possibly discomfort.

  • If there is a membrane over the anal opening, your baby may be unable to have a bowel movement.

  • If the rectum is not connected to the anus but there is a fistula present, stool will leave your baby's body through the fistula and enter the urinary tract instead of the anus. This can cause urinary infection.

  • If the rectum is not connected to the anus and there is not a fistula present, there is no way for the stool to leave the intestine.

    • Then, your baby will be unable to have a bowel movement and will have a blockage of the intestine as a newborn.
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