What is the underlying abnormality in Hirschsprung disease?
Hirschsprung disease is characterised by aganglionosis (absence of ganglion cells) in the distal colon and rectum.
How does one assess the length of aganglionic segment? Is this a reliable marker of histological abnormality?
A transition point in calibre from small distal to larger proximal. It should be noted however that the depicted transition zone on the contrast enema is not accurate at determining the transition between absent and present ganglion cells.
Barium enema demonstrates a reduced calibre rectum and sigmoid (the rectum is smaller than the descending colon) with a saw-tooth appearance to the wall. A transition point is seen at the junction between sigmoid and descending colon.