This prospective study, Randomized Trial of Indwelling Double-J Ureteral Stent Versus Externalized Modified-Salle Stent for Pyeloplasty will consist of four steps: 1.) Enrolling subjects in the study and signing the consent form 2.) Randomly divide subjects into 2 groups, group 1 will have internal stent and group 2 will have external stent 3.) At the time of stent removal in the clinic or in the OR subjects parents/ subjects will fill a questionnaire about pain after the procedure, stent care and stent tolerance and 4) Data from the questionnaires and procedure cost will be collected and all the data will be analyzed