Hirschsprung's disease / Congenital megacolon

Hirschsprung's disease, also known as congenital megacolon, is an abnormalityin which certain nerve fibers are absent in segments of the bowel, resultingin severe bowel obstruction.

The disease occurs approximately once in every 5,000 births, and is about four times more common in males than females. Hirschsprung's disease affects varying lengths of bowel segment, most often involving the region near the rectum. In 10% of affected children, the entire colon and part of the small intestine are involved.

Hirschsprung's disease is caused when cells in the wall of the colon (parasympathetic ganglion cells, which help control the movement of bowel contents) do not develop before birth. The affected segment of the intestine is prevented from relaxing and moving the bowel contents. As a result of this constriction, portions of the bowel above the affected segment are enlarged.

Hirschsprung's disease develops in the fetus early in pregnancy. There may bea genetic basis to the disease, since 4-50% of brothers and sisters are alsoafflicted and about 10% of children with the disease have a genetic condition, such as Down's syndrome.

The initial symptom is usually severe, continuous constipation. A newborn mayfail to pass the first stool within 24 hours of birth, may repeatedly vomityellow or green colored bile, and may have a swollen, uncomfortable abdomen.Occasionally, infants may have only mild or intermittent constipation, oftenwith diarrhea.

While two thirds of cases are diagnosed in the first three months of life, Hirschsprung's disease may also be diagnosed later in infancy or childhood. Occasionally, even adults are found to have a variation of the disease. In olderinfants, symptoms and signs may include anorexia (lack of appetite or inability to eat), lack of the urge to move the bowels, empty rectum during a doctor's physical examination, swollen abdomen, and a lump in the colon that can be felt by the doctor. It should be suspected in older children with abnormalbowel habits, especially a history of constipation dating back to infancy andribbon-like stools.

Occasionally, a child may have a severe intestinal infection called enterocolitis, which is life threatening. The symptoms are usually explosive, watery stools and fever in a very ill-appearing infant. It is very important to get medical attention before the intestinal obstruction causes an overgrowth of bacteria that evolves into a medical emergency. Enterocolitis can lead to severe diarrhea and massive fluid loss, which can cause death from dehydration unless surgery is done immediately to relieve the obstruction.

Hirschsprung's disease must be treated surgically. The goal is to remove thediseased, nonfunctioning segment of the bowel and restore bowel function. This is often done in two stages. The first stage relieves the intestinal obstruction by performing a colostomy. This is the creation of a stoma, an openingin the abdomen, through which bowel contents can be discharged into a waste bag. When the child's weight, age, or condition is deemed appropriate, surgeons close the stoma, remove the diseased portion of bowel, and perform a "pull-through" procedure, which connects the working part of the bowel to the anus.This usually establishes fairly normal bowel function.

Most infants with Hirschsprung's disease achieve good bowel control after surgery, but a small percentage of children may have lingering problems with soilage or constipation. These infants are also at higher risk for an overgrowthof bacteria in the intestines, including subsequent episodes of enterocolitis, and should be closely followed by a doctor.

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