This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pediatrics
The most common anomaly of the upper urogenital tract is 
Select and explain. 
A. Ureteropelvic junction stenosis, B. Ectopic uretheral opening, C. Ureterocele, D. Ectopic ureter
A: Ureteropelvic junction stenosis
Answer: A: Ureteropelvic junction stenosis 
Explanation: UPJ stenosis is the most common abnormality in childhood and is more frequent in male children, characterized by narrowing usually on the left sideOverall, position & shape of the kidney being most common oneHorseshoe kidney is the most common and most frequently found renal abnormality among men.(Refer: OP Ghai's Textbook of Pediatrics, 8th edition, pg no. 470)