Hirschsprung's disease in diagnosed by: March 2005

Ans. D: Rectal biopsyHirschsprung's disease/ congenital aganglionic megacolon, involves an enlargement of the colon, caused by bowel obstruction resulting from an aganglionic section of bowel (the normal enteric nerves are absent) that stas at the anus and progresses upwards.The most cited feature is absence of ganglion cells: notably in males, 75% have none in the recto-sigmoid, and 8% with none in the entire colon.The enlarged section of the bowel is found proximally, while the narrowed, aganglionic section is found distally; the absence of ganglion cells results in a persistent over-stimulation of nerves within the affected region, resulting in contraction.Delayed passage of meconium.'abdominal distension.Constipation.Suspect Hirschsprung's in a baby who has not passed meconium within 48 hours of delivery. (Recall that 90% of babies pass their first meconium within 24 hours, and the next 9% within 48 hours.)Definitive diagnosis is made by biopsy of the distally narrowed segment.