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': 'Not true about PUJ obstruction is - \nSelect and explain. \nA. Retrograde pyelography is useful to locate the site of obstruction, B. Endoscopic pylotomy is contraindicated, C. Whittakar test is of clinical significance, D. Dismembered pyloplasty is the procedure of choice', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Endoscopic approaches (such as endoscopic pyelotomy or ballon dilatation) are used for the repair of PUJ obstruction.', 'role': 'assistant'}]