Investigators conducted a previous retrospective study to evaluate other possible findings on ultrasound that may better predict reflux. Investigators found that if a postnatal ultrasound showed any of the three findings of hydroureter, duplication or dysmorphic kidney, then the odds ratio of detecting reflux was 8.07 (95%CI 3.86, 16.87). The purpose of this study is to perform a randomized prospective study to validate this retrospective study. Investigators hypothesis is that patients with hydronephrosis alone will be more likely to have negative VCUG studies; hence obtaining a VCUG for this indication may not be warranted.