This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intestinal obstruction, Subject name: Surgery
[{'content': 'A new born child has not passed meconium for 48 hours. What is the diagnostic procedure of choice? \nSelect and explain. \nA. USG, B. Contrast enema, C. CT, D. MRI', 'role': 'user'}, {'content': "Answer: B \nExplanation: Failure to pass meconium in the first 2 days of life (48 hours) is typically suggestive of a lower GI tract obstruction such as Hirschsprung's diseases, meconium plug syndrome or anorectal malformation. A contrast enema is the most suitable primary investigation to make the diagnosis, amongst the options provided.", 'role': 'assistant'}]