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': 'After a single episode of painless gross hematuria in a boy. Doctor performed an excretory urogram showing a filling defect towards the lower renal infundibulum 1.5 cm. in size. What will be the next investigation to be done ? \nSelect and explain. \nA. Cystoscopy, B. Urine cytology, C. USG, D. Retrograde pyelography', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' ie USG There can be various reason for a filling defect on IVP - stones, mass, cyst etc. They can be very well be diagnosed by USG.", 'role': 'assistant'}]