To compare percutaneous nephrostomy ( PCN ) tube vs JJ ureteric stenting as the initial urinary drainage method in children with obstructive calcular anuria ( OCA ) and post-renal acute renal failure ( ARF ) due to bilateral ureteric calculi , to identify the selection criteria for the initial urinary drainage method that will improve urinary drainage , decrease complications and facilitate the subsequent definitive clearance of stones , as this comparison is lacking in the literature .