HIRSCHSPRUNG DISEASE Hirschsprung Disease (HD), also known as congenital aganglionic megacolon , is a birth defect characterized by the absence of ganglion cells in the distal portion of the large intestine. Ganglion cells are part of the enteric nervous system, and they help regulate peristalsis—the muscle contractions that move food and stool through the intestines. Without these nerve cells, the affected segment of the colon cannot relax, leading to intestinal obstruction and difficulty in passing stool. PATHOPHYSIOLOGY: During fetal development, neural crest cells migrate to form the enteric nervous system along the gastrointestinal tract. In HD, this migration is incomplete, resulting in a section of the bowel that lacks ganglion cells. The aganglionic segment remains in a constant state of contraction (spasm), causing a functional obstruction. The proximal bowel dilates from the accumulation of feces and gas, leading to megacolon. CAUSES AND RISK FACTORS: Congenital de...
