Clearance While Upright on Initial Diuretic Renography Predicts the Need for Surgery in Children With Congenital Hydronephrosis

Objective: To improve the predictive ability of diuretic renography (DR) for surgical intervention in children with congenital hydronephrosis (CH) and concern for ureteropelvic junction obstruction. Methods: Children with CH born between 2007 and 2021 who underwent initial DR prior to 6 months of life, had both clearance while upright (CUP) and T ½ reported, and did not have immediate surgical intervention after the first DR were retrospectively evaluated for surgical intervention during the period of clinical observation. Once the optimal cut-points were identified for CUP and T ½, they were used to calculate the sensitivity, specificity, positive predictive value, and negative predictive value. Results: In total 65 patients were included in the final analysis with 33 (50.8%) undergoing surgical intervention (pyeloplasty) and 32 (49.2%) still on observation at last follow-up. The optimal cut-points for predicting surgical intervention were 28.1 minutes for T ½ and 22.4% for CUP. Applying the CUP cut-point of 22.4% we achieved a sensitivity of 60.6% (95% CI: 43.9-77.3), specificity of 96.9% (95% CI: 90.1-100.0), positive predictive value of 95.2% (95% CI: 86.1-100.0), and negative predictive value of 70.5% (95% CI: 57.0-83.9). Conclusion: A low CUP accurately predicts surgical intervention in children with CH who are initially observed. Although there is no singular measure on DR that can with absolute certainty predict future clinical course, our data do suggest there is utility in incorporating CUP (if <22.4%) into the decision process. Further research is necessary to help guide the management of children with intermediate CUP values.