Ureteropelvic junction obstruction (UPJO) is a common pathology in pediatric urology practice. Indications for intervention are well established while the ideal management of children with UPJO in poorly functioning kidneys is still debatable. We aimed in this study to evaluate the outcome of pyeloplasty in patients with UPJO and low DRF ≤ 20%.

We retrospectively evaluated 218 children with congenital UPJO from two tertiary hospitals between 2008 and 2018. We included only those with primary unilateral UPJO and DRF ≤ 20% on diuretic renography. Open dismembered pyeloplasty with stenting was carried out in all. Patients with bilateral UPJO, solitary kidney, DRF above 20%, association with other urinary anomalies and patients who underwent previous renal or ureteric surgeries and patients with missed follow-up were excluded. Clinical and radiological outcomes of this subgroup of patients were assessed.

A total of 21 patients (12 boys, 9 girls) with a median age at surgery of 2 years were included. Preoperative DRF ranged from 8-20% with a mean of 15% ± 3.5%. The median follow-up period was 2.5 years. Renal ultrasound showed improved HN in 16 patients (4 had a complete resolution) and stable in the remaining 5. Most of the improvement was noted in the first postoperative ultrasonography 16/21 (76%). Diuretic renography showed improved DRF by 10-15% in 8 patients (38%) while the remaining patients showed stable DRF with a non-obstructive curve with a mean improvement in DRF of 8 ± 5%. No postoperative complications were encountered and none of our patients required reintervention during follow-up.

The ideal management of children with UPJO and poorly functioning kidneys is still arguable. In our study we evaluated the outcome of pyeloplasty in patients with a low DRF ≤ 20% aiming to test the patients’ variables that can affect the improvement of DRF and HN grade after surgical intervention, however, none of these preoperative variables seemed to be a significant predictor.

Children with unilateral UPJO and DRF ≤ 20% have a favorable outcome after pyeloplasty. Improvement of HN in the first postoperative renal ultrasound is a good indicator for success.