Hirschsprung's disease

Definition

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

Description

Hirschsprung's disease is caused when cells in the wall of the colon (parasympathetic ganglion cells) do not develop before birth. The affected segment of the intestine lacks the ability to relax and move bowel contents along. As a result of this area of constriction, the bowel proximal (or above the stricture) dilates, producing megacolon (dilation of the colon). The disease affects varying lengths of bowel segment, most often involving the region around the rectum. In 10% of children, the entire colon and part of the small intestine are involved.

The disease occurs once in every 5,000 births, and it is about four times more common in males than females.

Causes & symptoms

Hirschsprung's disease develops in the fetus early in pregnancy when, for unknown reasons, nerve cells fail to develop in a segment of bowel. The absence of these nerve fibers, which help control the movement of bowel contents, results in intestinal obstruction and other symptoms. There may be a genetic basis to Hirschsprung's disease, since 4-50% of siblings are also afflicted 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 may fail to pass meconium (the first stool) within 24 hours of birth, may repeatedly vomit yellow or green colored bile, and may have a distended (swollen, uncomfortable) abdomen. Occasionally, infants may have only mild or intermittent constipation, often with 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 diagnosed with a variation of the disease. In older infants, symptoms and signs may include anorexia (lack of appetite or inability to eat), lack of the urge to move the bowels, empty rectum on physical examination, distended abdomen, and a mass in the colon that can be felt by the physician during examination. It should be suspected in older children with abnormal bowel habits, especially a history of constipation dating back to infancy and ribbon-like stools.

Occasionally, the presenting symptom may be 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. There is a great need to diagnose the condition 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.

Diagnosis

Hirschsprung's disease in the newborn must be distinguished from other causes of intestinal obstruction. The diagnosis is suspected by the child's medical history and physical examination, especially the rectal exam. The diagnosis is confirmed by a barium enema x ray, which yields a picture of the bowel. The x ray will indicate if a segment of bowel is constricted, causing dilation and obstruction. A biopsy of rectal tissue will reveal the absence of the nerve fibers. Adults may also undergo manometry, a balloon study of internal anal sphincter pressure and relaxation.

Treatment

Hirschsprung's disease must be treated surgically. The goal is to remove the diseased, 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 an opening in the abdomen (stoma) 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 repairs the colon by connecting functional bowel to the anus. This usually establishes fairly normal bowel function.

Prognosis

Overall, prognosis is very good. 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 overgrowth of bacteria in the intestines, including subsequent episodes of enterocolitis, and should be closely followed by a physician.

Prevention

Hirschsprung's disease is a congenital abnormality that has no known means of prevention. It is important to diagnose the condition early in order to prevent the development of enterocolitis.

Key Terms

Anus

The opening into the rectum, through which feces pass.

Barium enema x ray

A procedure that involves the administration of barium into the intestines by a tube inserted into the rectum. Barium is a chalky substance that enhances the visualization of the gastrointestinal tract on x ray.

Colostomy

The creation of an artificial opening into the colon through the skin for the purpose of removing bodily waste. Colostomies are usually required because key portions of the intestine have been removed.

Enterocolitis

Severe inflammation of the intestines that affects the intestinal lining, muscle, nerves, and blood vessels.

Manometry

A balloon study of internal anal sphincter pressure and relaxation.

Meconium

The first waste products to be discharged from the body in a newborn infant, usually greenish in color and consisting of mucus, bile, and so forth.

Megacolon

Dilation of the colon.

Parasympathetic ganglion cell

Type of nerve cell that is normally found in the wall of the colon.

Further Reading

For Your Information

Books

• Phillips, Sidney F., and John H. Pemberton. "Megacolon: Congenital and Acquired." In Sleisenger & Fordtran's Gastrointestinal and Liver Disease, edited by Mark Feldman, et al. Philadelphia: W.B. Saunders Co., 1998.

  Periodicals

• Fortuna, Randall S., et al. "Critical Analysis of the Operative Treatment of Hirschsprung's Disease." Archives of Surgery 131 (May 1996): 520.
• Swenson, Orvar. "Early History of the Therapy of Hirschsprung's Disease: Facts and Personal Observations Over 50 Years." Pediatric Surgery 31 (1997): 1003.

  Organizations

• American Pseudo-Obstruction & Hirschsprung's Society. 158 Pleasant St., North Andover, MA 01845. (978)685-4477.

Gale Encyclopedia of Medicine. Gale Research, 1999.