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.

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...