Hypothesis / aims of study
Pyeloplasty is the gold standard surgical intervention for ureteropelvic junction obstruction which entails removal of this obstruction. However, hydronephrosis (HN) may persist despite adequate surgical techniques, such as patent, water-tight and tension-free anastomosis. Resolution of HN is still not well understood and time to HN resolution varies greatly among individuals. As a result, postoperative follow-up protocols are different worldwide.
Study design, materials and methods
In a retrospective study, data of children who are younger than 15 years and underwent pyeloplasty at a tertiary center between January 2015 and October 2019 were reviewed. Patients who underwent redo pyeloplasty and those with missing data were excluded from the study. Resolution of HN was defined as decrease of the antero-posterior diameter (APD) to less than 10 mm or >50% reduction of the preoperative APD. Analysis of survival using Kaplan Meier`s curve was performed with adjustment to perioperative and clinical data.
Results
A total of 256 children were included in the study. Resolution of HN rate was 74.6%, 87.3%, 93.7% and 97% at 1, 2, 3 and 4 years of follow-up, respectively (Figure 1). Univariate analysis showed no difference in resolution neither between patients with preoperative APD <2, 2-4 and >4 cm (p= 0.15) nor between different HN grades (p=0.38). No difference was found among patient age groups <1, 1-5, 5-10 and >10 years old (Log rank 0.21). Bilateral cases and those with poorly functioning kidneys (<20% split renal function) did not show any difference in resolution of HN (Log rank 0.2 and 0.7 respectively). However, patients with solitary kidneys had less resolution rates (Log rank 0.03). On the other hand, cases with percent of improvement of APD (PIAPD) more than 10% within the initial visit showed significantly better resolution rates (Log rank 0.0001) (Figure 2). Both were significant in cox regression analysis.
Interpretation of results
Resolution of HN rate was more than 90% within 3 years of follow-up after pyeloplasty. There was no significant difference in resolution neither between patients with different preoperative APD nor between different grades of HN. No significant difference was also found among patient with different age groups. Bilateral cases and those with poorly functioning kidneys did not show any significant difference in resolution of HN. However, patients with solitary kidneys had less resolution rates. On the other hand, cases with PIAPD more than 10% within the initial visit showed significantly better resolution rates.