This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Congenital pyloric stenosis causes: 1. Bilious vomiting 2. Non- bilious vomiting 3. Projectile vomiting 4. Non projectile vomiting 5. Forceful \nSelect and explain. \nA. 1,2 & 4, B. 2,3,4 & 5, C. 1,3 & 4, D. All are seen', 'role': 'user'}, {'content': "Answer: B \nExplanation: The vomiting in pyloric stenosis may or may not be projectile, however non bilious vomiting after feed is the characteristic feature. In about 10-15% of infants vomiting may contain blood. This bleeding is due to reflux esophagitis, a common association with hyperophic pyloric stenosis. Also know: Associated anomalies occur in 6-20% of patients. These includes esophageal atresia, Hirschsprung's disease, anorectal anomalies, and intestinal malformation. Ref: Nelson 17/e, Page 1229.", 'role': 'assistant'}]