IRCT20141224020419N4 IRCT 2020-06-10 Mazandaran University of Medical Sciences UPJO treatment Comparison between surgical and conservative treatment for severe Ureteropelvic junction obstruction in pediatrics 2020-04-20 anticipated 30 Complete https://irct.ir/trial/41456 interventional Randomization: Not randomized, Blinding: Double blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Blinding description: Improvement status is the main variable that should be blinded. Therefore radiologist and scintigraphic reporters will be blinded. The scintigraphy reporter will be blinded in all times. But the sonographist will be blinded before operation. It is impossible to blind sonographist after surgery because of scar. N/A Condition 1: Urinary Tract Obstruction. Condition 2: congenital Hydronephrosis. Intervention 1: Intervention group: Hydronephrotic children (less than 18 years) with severe obstruction that are treated with surgical intervention (pyeloplasty). Intervention 2: Control group: Hydronephrotic children (less than 18 years) with severe obstruction that are not treated with surgical intervention (pyeloplasty). Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is There is no further information