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Question

You are consulted to see a 2-day old baby boy for failure to pass the first meconium stool and an episode of bilious emesis. He was 37-weeks gestation at the time of a normal spontaneous vaginal delivery without any complications. Physical examination reveals a distended abdomen and digital rectal exam results in an explosive expulsion of stool and gas. A contrast enema was ordered and is attached. What is the specific cause (not the diagnosis) of this infant’s condition and what is the next diagnostic step?

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Answer

This infant has congenital aganglionic megacolon, or Hirschprung Disease. It is caused by the failure of the neural crest cells (precursors to enteric ganglion cells) to migrate completely during intestinal development in utero. This results in the failure of the colon to be able to relax and causes a functional obstruction.

Diagnosis is made with bedside suction rectal biopsy 2cm above the level of the dentate line. Confirmatory findings on histology are abnormal acetylcholine esterase-positive nerve fibers in the mucosa.