<prompt> The most common anomaly of the upper urogenital tract isUreteropelvic junction stenosisEctopic uretheral openingUreteroceleEctopic ureter  <response>: 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 Ghais Textbook of Pediatrics, 8th edition, pg no. 470 