Digested matter normally passes through the intestine as a result of the rhythmic contraction of the muscles that line the gut (peristalsis). These muscles are stimulated to contract by nerve bundles, called ganglia, located between the muscle layers. In Hirschsprung's disease, the ganglia are missing, usually from only a few centimeters of bowel, but sometimes from long segments of bowel. Segments in which there is no peristalsis will not pass any digested matter beyond that point. The result is that the bowel cannot push material through and is effectively obstructed.
Intestinal contents accumulate behind the obstruction, causing the bowel and abdomen to become distended. If the condition is severe, the newborn may fail to pass meconium or stool, and the newborn may vomit. Milder cases may not be diagnosed until a later age. In older children, the disease may be characterized by chronic constipation, abdominal distention, and decreased growth rate.
Hirschsprung's disease causes one fourth of all newborn intestinal obstruction, but the condition may not be detected until later in infancy or childhood. It occurs 5 times more frequently in males than in females. Hirschsprung's disease is sometimes associated with other inherited or congenital conditions such as Down syndrome.
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