Changes in differential renal function after pyeloplasty in infants and children

Summary Introduction Ureteropelvic junction obstruction (UPJO) is one of the most common causes of hydronephrosis in pediatric populations. Many need surgical intervention. The aim of surgery is preserving renal function and reducing symptoms such as urinary tract infections and pain. Objectives The objectives were to evaluate differential renal function (DRF) in infants and children after surgery for UPJO and to identify factors predicting postoperative improvement. The difference in outcome between patients with antenatal hydronephrosis and those diagnosed later was evaluated. Study design 85 children (63 boys, 22 girls) aged 0-16 years, treated for UPJO with dismembered pyeloplasty, were followed according to a structured protocol including ultrasounds and renal scans (MAG-3) preoperatively and three and 18 months postoperatively. Five children with bilateral or single kidney UPJO were excluded. Patient records were retrospectively reviewed and the patients were grouped according to pre (group 1,n=23) or postnatal (group 2,n=57) diagnosis. Uni and multivariable logistic regression analyses searching for factors predicting >5% postoperative improvement in DRF on the obstructed side were performed. Factors included in analyses were age at diagnosis and surgery, sex, type of presentation, cause of obstruction, estimated gfr (e-gfr), preoperative DRF, anterio-posterior diameter (APD), APD/renal parenchymal thickness and grade of hydronephrosis according to Onen (grade 1-4). Results Preoperative DRF on the obstructed side was mean (SD) 42(12)% with no difference between groups. Median age at surgery was 0.9 (0.2-10) and 8.1 (0.6-16) years in groups 1 and 2 respectively (p 5% and one deteriorated. The proportion of patients with improved DRF was higher in group 1 (n=10; 45%, p=0.026). APD, APD/parenchymal thickness, preoperative DRF and antenatal diagnosis were predictors in the univariable analyses and high APD (OR1.1, p=0.0023), antenatal diagnosis (OR 0.23, p=0.048) and low preoperative DRF (OR 0.90, p=0.0045) built the best model of independent factors predicting improvement in DRF in multivariable analyses. (Summary Figure) Discussion The limitation of the study is that of being retrospective, but having the advantage of an uniform follow-up protocol including patients from a five year period with few lost to follow-up. The results can be of interest in evaluating factors of importance for predicting recovery of function in obstructive uropathies in children. Conclusion The majority of children had preserved or improved function after surgery for UPJO. Those with an antenatal diagnosis displayed a greater ability to catch up in DRF and high APD, antenatal diagnosis and low preoperative DRF were independent predictive factors of an improvement in renal function after pyeloplasty.