This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney & Ureturs, Subject name: Surgery
[{'content': '"adder head" appearance on excretory urography is seen in \nSelect and explain. \nA. Hydronephrosis, B. Infantile polycystic kidney, C. Ureterocele, D. Horseshoe kidney', 'role': 'user'}, {'content': 'Answer: C \nExplanation: (Ureterocele) (1310-LB) (1290-B & L 25th)Ureterocele is a cystic enlargement of the intramural portion of the ureter thought to result from congenital atresia of the ureteric orifice.* The "adder-head\' on excretory urography is typical* Usually the cyst wall is composed of urothelium only and the diagnosis is confirmed by the cystoscopic appearance of a translucent cyst enlarging and collapsing as urine flows in from the upper ureter.', 'role': 'assistant'}]