Factors Predicting Improvement of Renal Function After Pyeloplasty in Pediatric Patients: A Prospective Study

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.

Sonographic follow-up after pyeloplasty: a large, retrospective cohort analysis

PURPOSE

Routine scintigraphy after surgery for uretero-pelvic junction obstruction (UPJO) is discouraged, making ultrasound the preferred option for follow up. Yet, interpretation of sonographic parameters is rarely straightforward.

METHODS

We reviewed 111 cases including 97 pyeloplasty (52 open, 45 laparoscopic) and 14 pyelopexy during a 7-year period. Pre- and postoperative pelvic antero-posterior diameter (APD), cortical thickness (CT) and pelvis/cortex ratio (PCR) was measured serially.

RESULTS

85% were free of symptoms by 1 year. Only 11% had complete resolution of hydronephrosis. Eleven (10.4%) needed a redo procedure. Mean reduction in APD was 32.6%, 45.8%, and 51.7% at 6 weeks, 3 and 6 months respectively. CT increased by an average 55.9%, 75.6% and 107.6% while PCR reduced by 6.9, 8.0 and 8.8 at given intervals. Comparison of open and laparoscopic procedures showed no significant difference. Review of failed pyeloplasty showed failure of reduction in APD (APD > 3 cm or < 25% reduction) and PCR (PCR > 4) as early indicators for failure.

CONCLUSION

Both APD and PCR are reliable indicators of success and failure following pyeloplasty while CT alone is not as useful. Laparoscopic procedures are non-inferior to standard open surgery.

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.

The impact of post-procedural ureteric stent duration on the outcome of retrograde endopyelotomy for management of failed open pyeloplasty in children: a preliminary report

Background: To evaluate the outcome of retrograde endopyelotomy as a minimally invasive option for management of failed open pyeloplasty in children and assess how the duration of post-procedural stenting may affect the endopyelotomy outcome.

Methods: A total of 15 patients with secondary UPJO (Ureteropelvic junction obstruction) underwent retrograde endopyelotomy. The procedure was done using low-energy monopolar electrocautery hook under direct vision of pediatric ureteroscope and control of fluoroscopy. Double J stent was placed after the operation in all cases. Stent was removed in another session, 8 weeks (Group A, n=7) vs. 12 weeks (Group B, n=8) after endopyelotomy. Patients in both Groups were followed one, six and twelve months after the stent removal, and the anteroposterior renal pelvis diameter (APD), renal cortical thickness (CT) and degree of hydronephrosis (HDN) were recorded using the repeated measure test. P-value less than 0.05 were significant. We analyzed the data using SPSS software, version 20.

Results: The median interquartile range (IQR) age at time of surgery for group A and B were 24 (62) months and 12 (50) months respectively. Median (IQR) times between previous pyeloplasty and endopyelotomy were 6 (6) months and 12 (8.5) months in groups A and B, respectively. The success rate of endopyelotomy after 12 months was 57.1% in group A and 87.5% in group B. The resolution of HDN was more prominent in the 12 week stenting group compared to the 8 week group during the 12 months follow-up period (p=0.030). The APD and CT in group B compared to group A was improved during follow-up period.

Conclusion: A higher one-year success rate of retrograde endopyelotomy in terms of improvements in the degree of HDN, APD and CT was observed when the double j stent was remained for 12-weeks rather than 8-weeks. This observation need to be validated in a large cohort study with a long term post procedural follow up.

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.

Is it Always Necessary to Treat an Asymptomatic Hydronephrosis Due to Ureteropelvic Junction Obstruction?

The postnatal treatment of asymptomatic unilateral hydronephrosis due to ureteropelvic junction obstruction remains controversial, and the timing of and indications for surgical intervention are continuously debated. There is no consensus on the best follow-up during expectant management. The various modalities and parameters have been discussed along with their pros and cons and an attempt has been made to clear up the controversies.

Radiation-free monitoring in the long-term follow-up of pyeloplasty: Are ultrasound new parameters good enough to evaluate a successful procedure?

INTRODUCTION

Long-term evolution of residual hydronephrosis after successful pyeloplasty is not common. In this report, we have studied new ultrasound parameters, and have investigated the frequency of residual hydronephrosis. We highlight alternative radiation-free monitoring of pediatric pyeloplasties with ultrasound alone.

PATIENTS AND METHODS

Children who had undergone successful open Anderson-Hynes pyeloplasties in the period 2001-2010 were followed up. Exclusion criteria included non-clearly obstructed renography scans (tracer clearance half-time < 20 min), crossing vessels, failed pyeloplasty, bilateral disease, other renal concomitant anomaly, absence of ultrasound measurements, and loss to follow up (<1 year). Postoperative (postoperative) ultrasound parameters were anteroposterior (AP) diameter, pelvis-cortex (P/C) ratio, a proportion that takes in account these two values, enhancing sensitivity to evaluate minimal evolutive changes), and percentage of improvement (PI) in AP diameter (which reflects in relative means the evolution of each AP diameter, being 0% no change, and 100% absence of hydronephrosis) (Figure). Echographic checks were made at 3 and 6 months postoperatively and then yearly afterwards. SPSS software (v. 17.0 IBM, College Station, TX, USA) was used.

RESULTS

Out of 80 pyeloplasties performed in the above-mentioned period, 44 patients (i.e., 44 renal units) fulfilled the inclusion criteria for the main study. The median age at time of operation was 15 months (range 2 months-10.3 years). The median follow-up was 4.5 years (range 1-12 years). The mean preoperative anteroposterior diameter was 26 mm (range 16-54 mm). At the third postoperative check, the mean the PI was 29%, and rose to 53% at 6 months (p=0.027). Posterior controls showed a stable yearly PI during follow-up, without statistically significant variations (40-59% in subsequent years, p>0.5). The P/C ratio had already downgraded significantly at the third postoperative check (4.6 preoperative vs. 1.8 postoperative; p=0.03). A subgroup analysis of failed pyeloplasty (4 renal units) showed all PI < 15% at the third postoperative month (sensitivity 100%, specificity 86%). Complete resolution of hydronephrosis occurred in nine patients (20%).

DISCUSSION

The P/C ratio and PI are new feasible ultrasound parameters in pyeloplasty follow-up. Early improvement in the P/C ratio can be expected and might avoid repeated ionizing scans. A PI>15% in subsequent postoperative checks might be enough for safe monitoring with ultrasound alone. Thus, renograms may be solicited only in these cases where ultrasound parameters do not improve in the first 6 postoperative months. Afterwards, ultrasound parameters often remain stable in the long term. Absence of hydronephrosis could only be documented in the long term in one out of every five patients.

Delayed renal tissue tracer transit in Tc-99m-DTPA renography correlates with postoperative renal function improvement in UPJO patients

OBJECTIVE

The aim of the study was to explore the potential parameters for evaluating the improvement in relative renal function (RRF) in patients with unilateral ureteropelvic junction obstruction (UPJO) who underwent surgery. In this regard we observed the RRF expressed as the obstructed kidney's percentage contribution to overall renal function in technetium-99m diethylenetriaminepentaacetic acid (Tc-99m-DTPA) diuretic renography.

MATERIALS AND METHODS

Data on 47 patients, who underwent Anderson-Hynes pyeloplasty for diagnosed unilateral UPJO during the period of February 2003 to October 2014, were retrospectively collected. Tc-99m-DTPA diuretic renography was performed on all patients before and after surgery, and no morphological or functional abnormalities were detected on the contralateral kidney. Several parameters, especially renal tissue tracer transit (TTT), the response to furosemide stimulation, and RRF, were evaluated. All data were analyzed with the statistical software SPSS, 17.0, and a value of P less than 0.05 was considered statistically significant.

RESULTS

Data on 42 patients were eventually retained for further analysis; five patients were excluded because of indeterminate TTT. All patients showed obstructive response to furosemide stimulation with a preoperative RRF of 41±12%. Postoperative RRF of the obstructed kidneys was 47±11%, significantly higher than the preoperative RRF (P<0.05). Postoperative RRF improvement (absolute increment≥5%) was seen in 18/42 (43%) patients, and 24/42 (57%) of them manifested with postoperative drainage improvement. After surgery, both the RRF increment and the percentage of patients with postoperative RRF improvement in the preoperative delayed TTT group were significantly higher than those in the normal TTT group (12±7 vs. 2±4%, and 81 vs. 19%, respectively; P<0.05), but no significant difference in postoperative drainage improvement was detected between the two groups (56 vs. 54%, P>0.05). None of the other factors, including the preoperative RRF, obstructed kidney location, surgical method, sex, and age, had a significant influence on postoperative RRF improvement (P>0.05).

CONCLUSION

Preoperatively delayed TTT of Tc-99m-DTPA diuretic renography was an independent factor that correlated with RRF improvement of unilaterally hydronephrotic kidneys, and might provide valuable information for surgical decisions pertaining to UPJO patients.

Diagnostic accuracy of renal pelvic dilatation for detecting surgically managed ureteropelvic junction obstruction

PURPOSE

In this study we evaluate the diagnostic accuracy of renal pelvic dilatation for detecting infants with prenatal hydronephrosis who will need surgical intervention for ureteropelvic junction obstruction during followup.

MATERIALS AND METHODS

Between 1999 and 2010, 371 newborns diagnosed with isolated prenatal hydronephrosis were prospectively followed. The main event of interest was the need for pyeloplasty. Diagnostic odds ratio, sensitivity, specificity and diagnostic accuracy (assessed by AUC) of fetal renal pelvic dilatation and postnatal renal pelvic dilatation were evaluated.

RESULTS

A total of 312 patients were included in the analysis and 25 (7.5%) infants underwent pyeloplasty. The diagnostic performance for detecting the need for pyeloplasty was excellent for all ultrasonography measurements. The AUC was 0.96 (95% CI 0.92-0.98) for fetal renal pelvic dilatation, 0.97 (95% CI 0.95-0.98) for postnatal renal pelvic dilatation and 0.95 (95% CI 0.92-0.97) for the Society for Fetal Urology grading system. A cutoff of 18 mm for fetal renal pelvic dilatation and a cutoff of 16 mm for postnatal renal pelvic dilatation had the best diagnostic odds ratio to identify infants who needed pyeloplasty. Considering a diagnosis to be positive only if fetal renal pelvic dilatation was greater than 18 mm and postnatal dilatation was greater than 16 mm, sensitivity was 100% and specificity was 86% (95% CI 80.7-89.9).

CONCLUSIONS

Our findings suggest that the combination of fetal and postnatal renal pelvic dilatation is able to increase the diagnostic accuracy for detecting infants who need a more comprehensive postnatal investigation for upper urinary tract obstruction.