This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pediatric Surgery, Subject name: Surgery
[{'content': 'A 7-day old infant presents with bilious vomiting and gross abdominal distention with absent bowel sounds. X ray abdomen shows multiple gas filled loops. Diagnosis is? \nSelect and explain. \nA. Hirschsprung disease, B. Congenital Hyperophic pyloric stenosis, C. Duodenal atresia, D. Malrotation of gut', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Hirschsprung disease: No passage of meconium within 24 hours Abdominal distension Involvement rectum > sigmoid No vomiting Congenital Hyperophic pyloric stenosis: Misnomer (hyperophic pyloric stenosis is acquired) Therefore, known as infantile hyperophic pyloric stenosis Age of presentation is 4th to 6th week after bih Non bilious vomiting Duodenal atresia: Symptomatic just after bih Bilious vomiting Double bubble sign (therefore multiple gas filled loops are not seen) Malrotation of gut: Bilious vomiting Abdominal distention Multiple gas filled loops', 'role': 'assistant'}]