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': 'Indications of percutaneous nephrostomya) Stone removalb)  Ureteral obstructionc) Renal tumor resectiond) Ischemic renal failuree) Antegrade renography \nSelect and explain. \nA. bcde, B. abce, C. acde, D. abde', 'role': 'user'}, {'content': 'Answer: B \nExplanation: • For HDN, DJ stenting and percutaneous nephrostomy, both are having same results but DJ stenting is less invasive.\n• For pyonephrosis, percutaneous nephrostomy is better than DJ stenting.\n• Percutaneous nephrostomy is occasionally essential, if not life saving, in the treatment of acute or chronic upper urinary tract obstruction.\n• It is the first step in obtaining antegrade access to the kidney\xa0for various procedures.', 'role': 'assistant'}]