Factors Predicting Improvement Of Renal Function After Pyeloplasty In Children With Hydronephrosis And The Indication For Nephrectomy Based On Differential Renal Function

Objective:Previous series showed controversial differential renal function outcomes after pyeloplasty in children with hydronephrosis. However, they were limited by study power, methodology and lack of comparable end points. We assessed the specific preoperative renal scintigraphic, ultrasonographic and other factors that may be important in predicting renal function outcomes after pyeloplasty.Materials and Methods:After excluding children with renal anomalies, solitary kidney or bilateral hydronephrosis from our study, we retrospectively identified 213 children who were treated with pyeloplasty in our hospital between March 2008 and August 2012 and had preoperative renal scintigraphy and ultrasonography and postoperative scintigraphy available. Primary outcome measures were greater than 5% improvement in baseline differential renal function and baseline weighted differential renal function at the follow-ups. Clinical variables such as gender, lateral, age at the time of surgery, baseline differential renal function, preoperative renogram and the degree of hydronephrosis, predicting outcome measures were determined using multivariable analyses.Results:During a median followup of 7.5 months, mean±SD differential renal function improved from 32.61%±14.09% to-40.43%± 11.32%(p<0.001), the paired sample T test showed that postoperative differential renal function improved in all baseline DRF groups. In the poor group(DRF<40%) baseline differential renal function improved, while in the good group(DRF>40) function was static postoperatively. In the Logistic regression model baseline differential renal function, age at the time of surgery and the degree of hydronephrosis were the only predictors of a greater than 5% improvement in postoperative differential renal function.Conclusions:Differential renal function improves after pyeloplasty in children with hydronephrosis. Baseline differential renal function, age at the time of surgery and the degree of hydronephrosis predict improvement after surgery.Objective:The indication for pyeloplasty versus nephrectomy is mainly based on the results of DRF. Nephrectomy is usually recommended if DRF is less than 10%. However, recent studies indicate that even with an initial DRF of< 10%, a significant improvement of DRF may be seen when pyeloplasty is performed. The objective of the study is to confirm the indication for nephrectomy based on DRF in children.Materials and Methods:We retrospectively identified 128 children who were treated with pyeloplasty in our hospital between March 2008 and August 2012 and had preoperative and postoperative scintigraphy available. Patients were divided into 3 groups according to the initial DRF: group Ⅰ, DRF between 10-40%; group Ⅱ, DRF between 5-10%; group Ⅲ, SF of< 5%. The paired sample T test was used to analyse the changes of DRF after pyeloplasty in the 3 groups.Results:A total of 128 patients were included in the study, Group Ⅰ contained 102, group Ⅱ 20 and group Ⅲ 6 patients. The mean postoperative function increased 11.78% in group Ⅰ and 17.84% in group Ⅱ, decreased 0.26% in group Ⅲ. The paired sample T test showed that postoperative DRF improved in group Ⅰ and group Ⅱ, no improvement in group Ⅲ.Conclusions:Contrary to common practice we do not recommend nephrectomy for serious hydronephrotic kidneys which show less than 10% of DRF on renal scintigraphy. The renal functional status improves significantly after pyeloplasty, thus avoiding the need for nephrectomy for kidneys which show less than 10% of DRF. While, when DRF is less than 5%, nephrectomy may be justified.