This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small & Large Intestine, Subject name: Surgery
Investigation of choice in Hirschsprung's disease is: 
Select and explain. 
A. Rectal manometry, B. Rectal examination, C. Rectal biopsy, D. Ba enema
C: Rectal biopsy
Answer: C: Rectal biopsy 
Explanation: Ans. (c) Rectal biopsyRef: Schwartz 10th edition, Page 1625* Rectal biopsy must be taken 1,2 and 3cm above the dentate line in children under IV sedation.* In newborn no anesthesia is needed as biopsy is taken from pain insensitive area and hence done bedside.