Aganglionic segment is encountered in which pa of colon in case of Hirschsprung disease ?: (A) Distal to dilated segment, (B) In Whole colon, (C) Proximal to dilated segment, (D) In the dilated segment
Answer is A. Ans. is 'a' i.e., Distal to dilated segment Congenital aganglionic megcolon (Hirschsprung disease) o Hirshsprung disease a congenital disorder characterized by aganglionosis of a poion of the intestinal tract. o An intestinal segment lacks both Meissner submucosal and Auerbach myenteric plexuses. This leads to functional obstruction and intestinal dilation Proximal to the affected segment. o Histological findings are :- (i) Absence of ganglion cells and ganglia in the muscle wall and submucosa of the affected segment. (ii) Thickening and hyperophy of nerve trunk. o Rectum is always affected with involvement of more proximal colon to variable extent --> most cases involve the rectum and sigmoid only. o Proximal to the aganglionic segment, the colon undergoes progressive dilation and hyperophy. o With time, the proximal innervated colon may become massively distended --> megacolon.