This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Benign Gastric Disease, Subject name: Surgery
[{'content': 'Investigation of choice in pyloric stenosis- \nSelect and explain. \nA. USG, B. UGI series, C. CT, D. MRI', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e., USG o "The diagnosis of HP S is made by ultrasound scan or UGI series " - Sabistono "When olive cannot be palpated, ultrasonsgaraphy can diagnose the condition accurately in 95% of patients. Criteria for USG diagnosis include a channel length of> 16 mm and pylonic thickness of > 4 mm " - Schwartz', 'role': 'assistant'}]