Changes in Differential Renal Function after Pyeloplasty in Children

Is cortical transit time a parameter to prove relief of obstruction after pyeloplasty in antenatally diagnosed ureteropelvic junction obstruction

PURPOSE

The study aims to determine the possible improvement in cortical transit time (CTT) after surgery in infants with antenatally diagnosed ureteropelvic junction obstruction (UPJO), and investigate the correlation of CTT with preoperative renal function and parenchymal thickness.

PATIENTS AND METHODS

Medical charts of 32 antenatally diagnosed children with UPJO operated on between 2014 and 2021 were reviewed. Patients' demographics, preoperative and postoperative anteroposterior diameter (APD), parenchymal thickness (PT) ratio, differential renal function (DF), drainage patterns and CTT were compared to determine operative benefit. Preoperative CTT of each patient was also grouped as severely delayed (> 6 min) and moderately delayed (3-5 min) and compared. The correlation between the preoperative CTT and preoperative DF and PT ratio was investigated.

RESULTS

The median age of the patients was 8.8 months (1-24 months). The CTT (mean: 6.8 ± 3.0 min) was prolonged before surgery and was significantly improved (mean 4.6 ± 1.0 min) after the operation (p < 0.001). A significant negative correlation was detected between the CTT and preoperative DF and between the CTT and preoperative PT ratio. Preoperative DF was found significantly impaired in patients within the severely prolonged CTT group compared to those within the moderately prolonged CTT group. Significant improvement in DF was detected in patients in the severely prolonged CTT group after surgery.

CONCLUSION

CTT is a parameter to prove relief of obstruction in patients with antenatally diagnosed UPJO after surgery. CTT is negatively correlated with preoperative DF and PT ratio. Severely prolonged CTT may be considered to be an indication of early surgical intervention.

Is Percentage Improvement in Anteroposterior Pelvic Diameter a Valuable Marker for Successful Drainage Postpyeloplasty in Isolated Pediatric Pelvi-ureteric Junction Obstruction

Context

Pelvic-ureteric junction obstruction (PUJO) causes urine stasis in the renal pelvis and progressive kidney damage. Postpyeloplasty improvement of renal function and urinary drainage is assessed by diuretic isotope renogram and ultrasonography. Renograms are expensive and have radiation exposure. This study explores whether ultrasound parameters such as percentage improvement in anteroposterior pelvic diameter (PI-APD) is a valuable markers for successful pediatric pyeloplasties.

Aims

The aim of this study was to identify patients who would benefit from ultrasound monitoring of PI-APD alone instead of diuretic isotope renal scan for postoperative follow-up of pyeloplasty.

Settings and Design

This was a retrospective descriptive study.

Subjects and Methods

We analyzed 127 pediatric pyeloplasties performed and under follow-up between June 2016 and May 2021. We recorded the postoperative ultrasound and isotope renogram parameters. PI-APD (preoperative AP diameter - postoperative AP diameter)/preoperative AP diameter × 100) was compared with improvement in renogram parameters (differential renal function, Tmax, curve pattern, and retention) to look for a correlation between them.

Statistical Analysis Used

SPSS version 20.5, Chi-square and paired t-test were used for statistical analysis.

Results

About 73.2% of patients were males, with most cases detected antenatally (76.4%). The majority was left-sided PUJO (67.7%). The mean age at surgery was 30.8 months. We identified a statistically significant correlation between the ultrasound parameter PI-APD and the renogram parameter Tmax. There is no significant correlation between PI-APD and other renogram parameters.

Conclusions

In patients whose ultrasound parameter PI-APD is >40% and renal parenchymal thickness has increased, isotope renograms can be avoided for follow-up of postpyeloplasty patients.

Factors predicting improvement of differential renal function after pyeloplasty in children of ureteropelvic junction obstruction

INTRODUCTION

To evaluate differential renal function (DRF) in unilateral ureteropelvic junction obstruction (UPJO) patients under 18 years old after pyeloplasty and to identify factors predicting postoperative improvement.

MATERIAL AND METHODS

A total of 95 patients with unilateral UPJO treated by pyeloplasty between March 2019 to March 2020 were prospective enrolled. All patients had preoperative dynamic renal scintigraphy and were required to review after surgery 6 months. We defined DRF improvement as postoperative DRF increased ≥5% (If preoperative DRF less than 55%) or postoperative DRF reduced ≥5% and reached a normal range (45-55%) (preoperative DRF more than 55%) with drainage improvement. Drainage improvement indications were defined as a resolution of symptoms; decrease in hydronephrosis without requiring additional procedures and T_1/2＜20min in dynamic renal scintigraphy. All parameters were statistically compared.

RESULTS

In the study, 28 (29.5%) patients showed improvement in postoperative DRF, and 67 (70.5%) patients maintained stable postoperative DRF. Gender, age, baseline DRF, anteroposterior pelvic diameters (APD), minimum and maximum renal parenchymal thickness (PT), and anterior-posterior diameter/maximum renal parenchymal thickness (APD/PT) were correlated with postoperative DRF improvement in univariable analysis. In the multivariable analyses, maximum PT and APD/PT were predictors of improvement in postoperative DRF.

DISCUSSION

In our study, the maximum PT was associated with the improvement of renal function in patients with UPJO, and when the thickest part of the renal parenchyma was measured, APD/PT can predict the improvement of renal function. We infer that the compression of the thickest part of the renal parenchyma may be the reason for the impaired renal function in some patients, and when the obstruction was relieved, the compressed parenchyma function can be significantly improved.

CONCLUSIONS

Postoperative DRF of UPJO patients can be effectively improved and preserved through pyeloplasty. Maximum PT and APD/PT can predict improvement of renal function in patients with UPJO after pyeloplasty.

Pyeloplasty in children with low differential renal function: Functional recoverability

INTRODUCTION AND OBJECTIVE

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%.

STUDY DESIGN

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.

RESULTS

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 to 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.

DISCUSSION

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.

CONCLUSIONS

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.

Renal Cortical Thickness After Pyeloplasty in Pediatric Ureteropelvic Junction Obstruction

Purpose

The main goal of pyeloplasty is to maintain or improve renal function. Diuretic renography is the gold standard for evaluating renal function after pyeloplasty. Renal ultrasonography (RUS) is commonly used to determine hydronephrosis in pediatric patients. We hypothesized that the change in the renal parenchymal cortex would predict pyeloplasty success. In this study, we aim to measure renal cortical thickness change after pyeloplasty in ureteropelvic junction obstruction patients.

Materials and Methods

We retrospectively reviewed 38 patients who underwent pyeloplasty between 2005 and 2019. We divided patients into three age groups and compared the difference of renal parenchymal thickness change by using generalized estimating equations to identify associated factors for renal cortical thickness change after pyeloplasty.

Results

Thirty-nine kidney units were identified. The median age at the time of surgery was 41.61±40.99 months. Generalized estimating equations showed significant change of renal parenchymal thickness over the period of follow-up (p=0.02). The estimate of thickness change was 0.0373 mm/month. Age at the time of surgery was not associated with significant renal cortical thickness over the period of follow-up. The positive predictive factors for renal cortical thickness were creatinine clearance, pre-operative anteroposterior diameter and pre-operative renal differential function. The negative factors for decrease of renal cortical thickness were body weight, presentation with abdominal mass, and history of infection.

Conclusion

Renal cortical thickness after pyeloplasty was improved over the period of follow-up. Age at surgery was not associated with improvement of renal parenchymal thickness.

Pyeloplasty is a safe and effective surgical approach for low functioning kidneys with ureteropelvic junction obstruction

INTRODUCTION

Indications for treatment of ureteropelvic junction obstruction (UPJO) include symptomatic obstruction, urinary tract infections, presence of an obstructive pattern on functional renal scan and/or worsening differential renal function (DRF). This paper aims to determine the relationship between preoperative DRF and surgical outcomes after pyeloplasty. We hypothesized that low preoperative DRF is not an independent predictor of pyeloplasty failure.

METHODS

A retrospective chart review was performed to identify all patients undergoing pyeloplasty for UPJO between 2008 and 2019. Patients were included only if they had at least one preoperative functional scan and a minimum of one renal ultrasound post-operatively. Patients were divided into three groups based on DRF for analysis: Group 1- 0-10%, Group 2 - >10-≤20%, Group 3 - >20%. Baseline, intraoperative and postoperative characteristics, including success and complications were compared. Additional sensitivity analyses were performed comparing patients with ≤20%, and >20% function, ≤30%, and >30% function as well as an analysis of patients undergoing only minimally invasive reconstruction.

RESULTS

Three hundred and sixty-four patients met inclusion criteria. We identified 8 patients in Group 1, 24 patients in Group 2 and 332 patients in Group 3. Mean procedure time was longest for the ≤10% function group (237.9 vs 206.4 vs 189.1; p = 0.01). We found no difference in 30-day post-operative complications, overall success rate or the need for additional procedures among the three groups. For patients in Group 1, we noted variation in the post-procedure DRF with a range of -2.8 to +47% change. In this group, none of patients with low DRF underwent nephrectomy. Multivariate logistic regression did not identify renal function as a predictor of operative success OR 1.00 (95% CI: 0.97-1.03) (p-value: 0.88).

DISCUSSION

The results of the present study suggest that low DRF alone is not associated with worse outcomes and shows no difference in the failure rate. The incidence and type of complications were not increased for the lower functioning groups. The main limitation of this study would be its retrospective nature and single-institution experience. Furthermore, post-operative functional studies were not available for all patients, limiting the ability to draw conclusions on the change in DRF after surgery.

CONCLUSIONS

In a large cohort, preoperative DRF was not predictive of pyeloplasty success rate. DRF ≤10% was not associated with higher incidence of complications or failure rate. The DRF alone should not dictate the management options available for patients with UPJO.

Does relative renal function improve after intervention for chronic ureteric obstruction?

Introduction

Unilateral renal function often deteriorates with chronic ureteric obstruction. Our objectives were to determine the change in relative renal function (RRF) by MAG3 renography after intervention for ureteric obstruction, and to identify clinical/epidemiological factors which influence long-term outcomes.

Material and methods

We identified 228 patients from 2006 to 2017 who underwent MAG3 renography before and after intervention for unilateral ureteric obstruction. Patients were grouped into categories preoperatively - with normal RRF (43–57%) through mild (29–42%), moderate (15–28%) and severe (<15%) impairment of RRF. Patient demographics, types of obstructive uropathy and intervention employed were analysed. Each group was assessed for the absolute change in RRF and change in RRF category postoperatively.

Results

The mean patient age was 50.4 years (SD 16.7), and 62.3% were female. Overall, the mean pre- and post-intervention RRF of the obstructed kidney did not differ significantly (32.30% vs. 32.20%, P = 0.835). Most patients remained in their preoperative RRF group: 85.9% of normal, 67.4% of mild, 64.4% of moderate and 73.3% of patients with severe RRF impairment did not change category.

Patients with mildly impaired preoperative RRF showed a significant worsening postoperatively (36.37% vs. 34.58%, P = 0.024). The other three groups showed no significant change in RRF following intervention.

Multivariate logistic regression analysis showed no statistically significant association between type of intervention, age, gender or diagnosis and improvement in postoperative RRF category.

Conclusions

Our results show that RRF does not improve significantly after intervention for ureteric obstruction. The aim should therefore be to maintain existing renal function and relieve symptoms.

A comparison between short- and long-term D-J stent in Anderson-Hynes pyeloplasty for pelvi-ureteric junction obstruction

PURPOSE

A double-J (D-J) stent is usually kept in situ during Anderson-Hynes (A-H) pyeloplasty for pelvi-ureteric junction (PUJ) obstruction. The aim of the study is to determine whether early removal of D-J stent is better than long-term stenting.

METHODS

In this prospective comparative study, conducted from January 2018 to April 2019 in Chittagong Medical College Hospital, patients with PUJ obstruction, age less than 12 years, were divided into group A (long-term stenting) and group B (short-term stenting) by simple randomization. Main outcome variables were urinary tract infection (UTI), stent colonization, encrustation, renal cortical thickness, differential renal function (DRF), glomerular filtration rate (GFR), and flow rate in DTPA renogram.

RESULTS

There were 31 patients in each group. Median age was 5 years (IQR: 2.3 to 7 years) and male to female ratio was 2.1:1. Frequency of post-operative UTI and stent colonization were significantly higher in group A than group B (p < 0.001). All the patients of both groups had similar improvement in renal cortical thickness, DRF, GFR, and flow rate. The study was potentially limited by its small sample size and high median age (5 years).

CONCLUSION

Early removal of D-J stent had lower incidence of UTI, stent colonization, encrustation, and stent migration.

Changes in differential renal function after pyeloplasty in infants and children

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 outcomes between patients with antenatal hydronephrosis and those diagnosed later was evaluated.

STUDY DESIGN

A total of 85 children (63 boys and 22 girls) aged 0-16 years, treated for UPJO with dismembered pyeloplasty, were followed up as per a structured protocol including ultrasounds and renal scans (MAG-3) pre-operatively 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 as per prenatal (group 1, n = 23) or postnatal (group 2, n = 57) diagnosis. Univariable 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 glomerular filtration rate, pre-operative DRF, anteroposterior diameter (APD), APD/renal parenchymal thickness, and grade of hydronephrosis as per the Onen alternative grading system (grade 1-4).

RESULTS

Pre-operative DRF on the obstructed side was a mean of 42% (standard deviation, 12), with no difference between the groups. The median age at surgery was 0.9 (0.2-10) and 8.1 (0.6-16) years in groups 1 and 2, respectively (P < 0.001). The majority had unchanged DRF 18 months postoperatively, 19 (27%) patients improved by >5%, and one deteriorated. The proportion of patients with improved DRF was higher in group 1 (n = 10; 45%, P = 0.026). Anteroposterior diameter, APD/parenchymal thickness, pre-operative DRF, and antenatal diagnosis were predictors in the univariable analyses, and high APD (odds ratio [OR] = 1.1, P = 0.0023), antenatal diagnosis (OR = 0.23, P = 0.048), and low pre-operative 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 it is retrospective, but it has the advantage of a 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 pre-operative DRF were independent predictive factors of an improvement in renal function after pyeloplasty.

Predictors of Renal Functional Improvement After Pyeloplasty in Ureteropelvic Junction Obstruction: Clinical Value of Visually Assessed Renal Tissue Tracer Transit in 99mTc-mercaptoacetyltriglycine Renography

OBJECTIVE

To determine the clinical value of visually assessed renal tissue transit time (TTT) in ^99mTc-mercaptoacetyltriglycine (^99mTc-MAG3) renography for patients undergoing pyeloplasty.

MATERIALS AND METHODS

Medical records of 164 patients who underwent dismembered pyeloplasty were retrospectively reviewed. Baseline and postoperative renal ultrasonography and ^99mTc-MAG3 renography were performed. Two urologists blinded to clinical data evaluated the renography and classified TTT as timely or delayed based on visualization of the tracer in the kidney pelvis between 2 and 10 minutes. Renal functional change after pyeloplasty was compared between patients in the timely and delayed groups.

RESULTS

A total of 126 patients (median age, 9 months) were evaluated after excluding patients with bilateral ureteropelvic junction obstruction, a single functioning kidney, duplicated ureter, or <3 months of follow-up. There were no differences between 89 patients with timely TTT and 37 patients with delayed TTT in mean preoperative hydronephrosis grade (3.7 vs 3.8) and pelvic diameter (3.1 cm vs 3.4 cm). Although the pre- and postoperative mean values of differential renal function (DRF) were significantly higher in the timely group than in the delayed group (47.2% vs 38.3% and 47.9% vs 44.6%), DRF change was greater in the delayed group (6.3% vs 0.6%). In multivariate analysis, delayed TTT was the only significant predictor of >5% improvement in renal function after pyeloplasty.

CONCLUSION

Delayed TTT in ^99mTc-MAG3 renography was a significant predictor of renal functional improvement after pyeloplasty in ureteropelvic junction obstruction. Because substantial improvement of renal function is anticipated, we recommend immediate pyeloplasty in patients with delayed TTT and decreased DRF.

Percent improvement in renal pelvis antero-posterior diameter (PI-APD): Prospective validation and further exploration of cut-off values that predict success after pediatric pyeloplasty supporting safe monitoring with ultrasound alone

INTRODUCTION

Renograms are frequently obtained post-pyeloplasty in patients with residual hydronephrosis to confirm adequate drainage. Recent evidence suggests that percent improvement in antero-posterior diameter (PI-APD) ≥38 is predictive of success. We sought to further explore PI-APD ranges that would allow identification of patients who would benefit from ultrasound (US) monitoring alone vs. post-operative renal scan, and those more likely to develop recurrent ureteropelvic junction obstruction (rUPJO).

METHODS

A single-center prospectively-collected pyeloplasty database (2008-2015) was queried (n = 151). Only patients with both pre- and post-operative APD measurements were included (n = 138). PI-APD was divided into 3 categories: <20%; 20-39%; ≥40%. The following variables were collected post-operatively: patients monitored with US alone, renogram and US, rUPJO and minimal or resolved hydronephrosis (SFU ≤2; UTD ≤1; APD ≤15 mm).

RESULTS

Mean age at first and last follow-up were 4.8 (median 4.0; range 0-60) months and 26.6 (median 20.5; range 1-77) months, respectively. Of 138 patients, 84 (61%) had US alone, 54 (39%) had a renogram and US post-operatively, and 6 (4%) developed rUPJO. Of 84 patients who had US alone, 71 (84%; p < 0.01) demonstrated ≥40% PI-APD. Of 54 patients with renogram and US 46 (85%; p < 0.01) had ≥40 PI-APD. Of the 6 patients who developed rUPJO, all were in the <20 PI-APD group (100%; p < 0.01). Resolution of hydronephrosis according to SFU, UTD and APD occurred in 96/138 (70%), 89/138 (64%) and 113/138 (82%) patients respectively. Of these, 87 (91%), 81 (91%), and 108 (95%) occurred in >40% PI-APD group.

CONCLUSION

≥40% PI-APD at the first post-operative visit strongly predicts pyeloplasty success, as up to 82% of these patients showed resolved hydronephrosis and 61% underwent non-invasive monitoring by US alone. Our data suggests that up to 85% of renograms may have been unnecessary. Finally, <20% PI-APD permitted identification of all rUPJO cases. Stratification of patients based in PI-APD is a promising strategy for further minimizing radiation exposure while safely detecting children at risk for rUPJO.

Comparative Outcome Analysis of Children Who Underwent Pyeloplasty for Ureteropelvic Junction Obstruction Associated With or Without Supranormal Differential Renal Function

OBJECTIVE

To compare pyeloplasty outcomes in children with and without "supra-normal" differential renal function (SNDRF) defined as >55% differential renal function (DRF) in children with ureteropelvic junction obstruction.

METHODS

Our prospectively collected pyeloplasty database (2008-2015) was reviewed (n = 151). A total of 140/151 (93%) patients had preoperative renograms and 26/140 (19%) were found to have SNDRF (DRF ≥ 55%). Of 151 patients, 51 (34%) had pre- and postoperative renograms allowing determination of change ≥5% in function. After excluding 2 patients with solitary kidneys, a total of 49 patients defined the study group.

RESULTS

Of 49 patients, 12 had SNDRF and 37 did not. Baseline characteristics were similar including mean age at surgery (47.3 months vs 45.4 months) and time to surgery (8.7 months vs 9.8 months). Mean preoperative anteroposterior diameter was significantly different between groups (23.2 mm vs 31.0 mm; P = .04), but postoperative was similar (9.0 mm vs 12.1 mm; P = .14). Mean preoperative DRF was 60.2% in the SNDRF group vs 44.3% in the non-SNDRF. Mean postoperative DRF was 52.4% and 45.3%, respectively (P = .04). There were 9/12 (75%) SNDRF patients who experienced ≥5% loss in function compared to 2/37 (5%) in the non-SNDRF group (P < .01).

CONCLUSION

Three-quarters of SNDRF patients demonstrated a decline of ≥5%DRF postoperatively when compared to non-SNDRF. This finding may not reflect true elevated renal function, but rather hyperfiltration in the setting of obstruction, which-if unrecognized as such-could result in postponing an otherwise beneficial surgical intervention.

Objective improvement in renal function post-Dietl's crisis: Documented on renal dynamic scintigraphy

Dietl's crisis is one of the treatable causes of intermittent abdominal pain. The pain is due to acute hydronephrosis that leads to stretching of the pelvis. The most common cause of this intermittent hydronephrosis is aberrant renal vessel at lower pole that causes pelvi-ureteric junction obstruction.(PUJO). High insertion of the ureter is one of the other rare causes. We present a case of 5-year-old boy with intermittent abdominal pain and distension with ultrasonography features of gross left hydronephrosis. Renal dynamic scan.(RDS) with ethylene dicysteine showed negligible functioning left kidney. On third follow-up day, the patient passed a lot of urine with decrease in abdominal pain and distension. Then, again the patient was sent to us 8.days after the first study for repeat RDS, which showed significant improvement in function and decreased in the size of left kidney though with persistent PUJO. On exploration high insertion of the ureter at pelvis was found to be the cause and was treated.

Delayed redo pyeloplasty fails to recover lost renal function after failed pyeloplasty: early sonographic changes that correlate with a loss of differential renal function

Purpose

To evaluate changes in differential renal function (DRF), as a functional outcome, in children who underwent redo pyeloplasty for management of failed pyeloplasty and to examine the factors that affect functional outcomes.

Materials and Methods

Between January 2002 and November 2010, a total of 18 patients who underwent redo pyeloplasty for persistent ureteropelvic junction obstruction after failed pyeloplasty were enrolled in this study. We assessed perioperative factors and evaluated changes in renal cortical thickness (RCT), renal function, and hydronephrosis by use of serial ultrasound and diuretic renography.

Results

The mean follow-up period was 44.83±28.86 months. After redo pyeloplasty, prevention of further functional deterioration was observed in only 12 of the 18 patients. After dividing the patients according to this observation, we discovered significant differences in both change in DRF (dDRF) and change in RCT (dRCT) (difference between before and after initial pyeloplasty) between the two groups (p<0.001). Additionally, we noted a significant positive correlation between dRCT and dDRF. All patients showed improvements in hydronephrosis grade and relief of symptoms compared with before redo pyeloplasty.

Conclusions

Redo pyeloplasty should be considered in cases of failed pyeloplasty to preserve renal function and obtain relief from symptoms. If patients show severe deterioration of DRF or a decrease in RCT after initial pyeloplasty, preservation of DRF in these patients after redo pyeloplasty could be difficult. Therefore, redo pyeloplasty should be performed before severe deterioration of DRF or decrease in RCT.