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Anorectal malformations are defects that occur during the fifth to seventh week of fetal development. With these defects, the anus (opening at the end of the large intestine through which stool passes) and the rectum (area of the large intestine just above the anus) do not develop properly. The exact cause is unknown.
Normally, during a bowel movement stool passes from the large intestine to the rectum and then to the anus. Nerves in the anal canal help us sense the need for a bowel movement and also stimulate muscle activity. Muscles in this area help control when we have a bowel movement.
With an anorectal malformation, any of the following abnormalities can occur:
Approximately 1 in 5,000 children are born with anorectal malformation. It occurs slightly more often in males than in females. The best outcomes are achieved when immediate and correct diagnosis and treatment of the disorder are made at the time of birth.
Depending on the type and severity of the anorectal malformation, a number of problems can occur:
Approximately 50 percent of babies with anorectal malformations have other abnormalities. These commonly include:
When a baby is born, the physician performs a thorough physical examination that includes seeing if the anus is open and in the proper position. A number of diagnostic tests might also be done to further evaluate a problem and to determine whether other abnormalities are present:
Treatment recommendations will depend on the type of anorectal malformation, the presence and type of associated abnormalities, and the child’s overall health. However, most infants with an anorectal malformation will require surgery.
Newborn boys and girls diagnosed with anorectal malformations without a fistula will require one or more operations to correct the malformation. An operation to create a colostomy is usually performed initially. This surgical procedure creates a stoma, an opening on the abdomen through which the waste passes.
With a colostomy, the large intestine is divided into two sections, and the ends of the intestine are brought through small openings on the abdominal wall.
The upper section allows stool to pass through the stoma in to a collection bag. The second, smaller stoma is called a mucus fistula. The purpose of the mucus fistula is to drain bowel secretions from the bottom portion of the stoma.
By creating a colostomy, digestion will not be impaired and the baby can grow before the next required operation.
Nursing staff and Colorectal program staff who work with the baby’s surgeon will help parents learn how to take care of the colostomy, and will help them make the transition from the hospital to home. Local and national support groups may also be very helpful at this time. Ask the surgeon or nurse for resources available.
Surgery - Pediatric
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