This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, 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: The most common obstructed lateral fusion defects is unilateral obstruction and is most commonly seen in women with complete duplication of the reproductive tract(double uterus, cervix and vagina) . Unilateral UPJ obstruction is the most common prenatally detected obstructive disease, often picked up on maternal ultrasounds during pregnancy. Reference: GHAI Essential pediatrics, 8th edition