This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nephropathy, Subject name: Pediatrics
Most common anomaly of upper urogenital tract is - 
Select and explain. 
A. Uretero pelvic junction stenosis, B. Ectopic uretheral opening, C. Ureterocele, D. Ectopic ureter
A: Uretero pelvic junction stenosis
Answer: A: Uretero pelvic junction stenosis 
Explanation: Ans. is 'a' i.e., Uretero pelvic junction stenosis o UPJ stenosis is most common abnormality in childhood and is more frequent in male children, characterised by narrowing usually on left side.o Overall, position & shape of kidney being most common one.o Horse shoe kidney is the most common and most frequently found renal abnormality among men.