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Introduction: Hydronephrosis grading systems risk stratify patients with potential ureteropelvic junction obstruction, but only some criteria are measured objectively. Most notably, there is no consensus definition of renal parenchymal thinning., Objectives: The objective of this study was to assess the association between sonographic measures of renal length, renal pelvic diameter, and renal parenchymal thickness and the outcomes of a)renal hypofunction(differential renal function{DRF} <40%) and b)high-risk renal drainage(T1/2 > 40 min)., Study Design: An institutional database of patients who had diuretic renograms(DR) for unilateral hydronephrosis was reviewed. Only infants with Society for Fetal Urology(SFU) grades 3/4 hydronephrosis without hydroureter on postnatal sonogram and had a DR within 120 days were included. The following measurement variables were analyzed: anterior posterior renal pelvic diameter(APRPD), renal length(RL), renal parenchymal thickness(PT), minimal renal parenchymal thickness(MPT = shortest distance from mid-pole calyx to parenchymal edge), and renal pyramidal thickness(PyrT). RL, PT, MPT, PyrT measurements were expressed as ratios (hydronephrotic kidney/contralateral kidney). Multivariate logistic regression was performed for each outcome by comparing three separate renal measurement models. Model 1: RLR, APRPD, MPTR; Model 2: RLR, APRPD, PTR, Model 3: RLR, APRPD, PyrTR. Individual performance of variables from the best performing model were assessed via ROC curve analysis., Results: 196 patients were included (107 with SFU grade 3, 89 with SFU grade 4) hydronephrosis. Median patient age was 29[IQR 16,47.2] days. 10% had hypofunction, and 20% had T1/2 > 40 min 90% with hypofunction and 87% with high-risk drainage had SFU4 hydronephrosis. Model 1 exhibited the best performance, but on multivariate analysis, only APRPD and MPTR were independently associated with both outcomes. No other measure of parenchymal thickness reached statistical significance. The odds of hypofunction and high-risk drainage increase 10% per 1 mm increase in APRPD(aOR 1.1 [CI 1.03-1.2], p = 0.005; aOR 1.1 [CI 1.03-1.2], p = 0.003). For every 0.1unit increase in MPTR the odds of hypofunction decrease by 40%(aOR 0.6 [CI 0.4-0.9], p = 0.019); and the odds of high-risk drainage decrease by 30%(aOR 0.7 [CI 0.5-0.9], p = 0.011). Optimal statistical cut-points of APRPD >16 mm and/or MPTR <0.36 identified patients at risk for obstructive parameters on DR., Discussion and Conclusion: Of the sonographic hydronephrosis measurement variables analyzed, only APRPD and MPTR were independently associated with objective definitions of obstruction based on renal function and drainage categories. Patients who maintain APRPD <16 mm and/or MPTR >0.36 can potentially be monitored with renal sonograms as there is >90% chance that they will not have DRF<40% or T1/2 > 40 min., Competing Interests: Conflict of interest Neither I, nor any of the authors, have any conflicts of interest to disclose., (Copyright © 2024 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Background/objective: While there is significant data on the natural history and outcomes for prenatal hydronephrosis in simplex kidneys, duplex kidneys tend to be less studied. Management can be quite variable based on provider preference. We aimed to describe practice patterns from several tertiary academic institutions, identify clinical predictors for surgical intervention and urinary tract infection (UTI) for upper pole pathology, and demonstrate the natural history of lower pole vesicoureteral reflux (VUR)., Methods: We conducted a retrospective review of patients from 4 Mid-Atlantic institutions between 2015 and 2020. Inclusion criteria included patients with a duplex kidney with upper pole pathology and/or lower pole VUR. The primary outcome was predictive factors for surgical intervention and UTI. The secondary outcome was to assess the natural history of lower pole VUR including resolution rates by grade. Linear regression identified clinical predictors for UTI events. Multivariate logistic regression identified predictors of surgical intervention, UTI, and lower pole VUR resolution. Descriptive statistics and regression modeling analyses were performed using SAS., Results: Two hundred forty-two patients were included with a total of 271 duplex renal units. Hydronephrosis grade (both SFU and UTD grading) and number of prior UTI events were statistically significant predictors for surgical intervention (p = 0.03/0.001 and p = 0.002 respectively). Ectopic ureter (p = 0.004), ureterocele (p = 0.02), and obstruction (p = 0.04) were the only pathologies predictive for surgery. Male gender and circumcision were significantly associated with decreased UTI risk (p = 0.03 and p = 0.01). On linear regression modeling, antibiotic prophylaxis after the first year of life was associated with decreased risk of further UTI events (p = 0.03); however, antibiotic prophylaxis within the first year of life did not decrease UTI risk (p = 0.14). For VUR outcomes, 65.0% of grades 1-3 VUR and 52.2% of grades 4-5 had resolution/improvement at mean time of 2.1 years. There were no predictive factors for resolution/improvement of VUR., Conclusions: Hydronephrosis grade and UTI events were significant predictors for surgical intervention for upper pole pathology. Pathologies that were predictive for surgery included ectopic ureter, ureterocele and obstruction. Male gender, circumcision and antibiotic prophylaxis after the first year of life were associated with a decreased UTI risk. Roughly 58% of lower pole VUR spontaneously improved/resolved. Identification of these risk factors aids in standardization of care practices to reduce long-term UTI risk and inform counseling with families about possible need for surgical intervention and expectations for long term outcomes., (Copyright © 2022 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Introduction and Objective: Prior studies have shown a broad half time (T1/2) interval on MAG3 diuresis renography (DR) that is indeterminate for obstruction. We aimed to refine and sub-divide the indeterminate range and associate it with clinically meaningful outcomes: pyeloplasty and pyeloplasty-free survival., Methods: We identified patients <1.5 years-old at presentation with unilateral, isolated moderate to severe hydronephrosis who underwent DR from 2000 to 2016. A logistic regression model was created using T1/2 to predict surgery. An indeterminate range was defined based on patients with <90% probability of pyeloplasty or resolution. This group was sub-divided into three T1/2 intervals: 5-20, 21-40, and 41-60 min. Endpoints were pyeloplasty and pyeloplasty free survival. Indications for surgery were loss of differential renal function (DRF), worsening T1/2, family preference, and/or pain., Results: Among 2025 patients with DR, 704 met criteria (169 were lost to follow up). Of the remaining 535, 218 had pyeloplasties and 317 did not. The Pyeloplasty group had significantly worse DRF, T1/2 at initial DR, and exited the study earlier, at a median age 1.1years vs 2.3 years (p < 0.001). For all patients with antenatally detected unilateral UPJ obstruction, the odds of undergoing pyeloplasty at any time increased by 1.8 times (p < 0.001 [95% CI: 1.04, 1.08]) per 10 unit increase in T1/2 until T1/2 = 60. However, in patients with intermediate drainage, five year surgery-free survival probability for patients with T1/2 5-20, 21-40, and 41-60 min were 79.7%, 46.7% and 33.3% respectively (χ2 = 41.2, P = <0.001)., Discussion: Previous efforts to define indeterminate drainage resulted in ranges for T1/2 that were too broad to be clinically useful. Within our endpoint-defined indeterminate range, our data show that there are significant step offs in 5-year surgery-free survival for patients with T1/2 < 20 min, 21-40 min, and 41-60 min. Although there is a steady decrease in surgery-free survival among patients with a T1/2 of 21-40 min over the first 5 years of life, half can be managed nonoperatively. These patients likely represent the true intermediate risk group and closer follow up is justified., Conclusions: Initial T1/2 on DR is predictive of future surgery. When drainage is "indeterminate" for obstruction, sub-stratification allows for more accurate prognostication., Competing Interests: Conflicts of interest Neither I, nor any of the other authors, have any financial disclosures or conflicts of interest., (Copyright © 2021 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Purpose: We sought to define features that describe the dynamic information in diuresis renograms for the early detection of clinically significant hydronephrosis caused by ureteropelvic junction obstruction., Materials and Methods: We studied the diuresis renogram of 55 patients with a mean ± SD age of 75 ± 66 days who had congenital hydronephrosis at initial presentation. Five patients had bilaterally affected kidneys for a total of 60 diuresis renograms. Surgery was performed on 35 kidneys. We extracted 45 features based on curve shape and wavelet analysis from the drainage curves recorded after furosemide administration. The optimal features were selected as the combination that maximized the ROC AUC obtained from a linear support vector machine classifier trained to classify patients as with or without obstruction. Using these optimal features we performed leave 1 out cross validation to estimate the accuracy, sensitivity and specificity of our framework. Results were compared to those obtained using post-diuresis drainage half-time and the percent of clearance after 30 minutes., Results: Our framework had 93% accuracy, including 91% sensitivity and 96% specificity, to predict surgical cases. This was a significant improvement over the same accuracy of 82%, including 71% sensitivity and 96% specificity obtained from half-time and 30-minute clearance using the optimal thresholds of 24.57 minutes and 55.77%, respectively., Conclusions: Our machine learning framework significantly improved the diagnostic accuracy of clinically significant hydronephrosis compared to half-time and 30-minute clearance. This aids in the clinical decision making process by offering a tool for earlier detection of severe cases and it has the potential to reduce the number of diuresis renograms required for diagnosis., (Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose: In infants with SFU (Society for Fetal Urology) grade 3-4 congenital hydronephrosis, 99m Tc-mercaptoacetyltriglycine diuretic renography assesses differential function and drainage half-time. We routinely also include the percent of radiotracer drained after 30 minutes of diuresis as well as after 15 minutes with the patient in the upright position. We investigated whether any 1 or more of these parameters on initial diuretic renography predicts persistent or worsening drainage parameters., Materials and Methods: Infants 6 months or younger with grade 3-4 congenital hydronephrosis who presented between January 2009 and December 2014 were identified from billing data and included in analysis if they underwent at least 1 baseline diuretic renography. Those with structural anomalies were excluded from study. Baseline and followup differential function, diuresis half-time, clearance at 30 minutes and clearance with the patient upright were abstracted and comparisons were made between those with initially indeterminate diuresis half-time who underwent pyeloplasty vs those showing spontaneous improvement., Results: A total of 74 patients (82 renal units) with presumed ureteropelvic junction obstruction met inclusion/exclusion criteria. All 10 renal units with initial diuresis half-time less than 5 minutes resolved spontaneously and all 25 renal units with initial diuresis half-time greater than 75 minutes underwent pyeloplasty. Therefore, we defined the indeterminate group as the 47 renal units with initial half-time between 5 and 75 minutes. Of those 47 renal units with indeterminate initial diuresis half-time 23 (47%) underwent pyeloplasty and 25 (53%) resolved spontaneously. Indications for pyeloplasty included worsening in 17 cases, persistent obstruction in 4 and urinary tract infection in 1. Among renal units with indeterminate drainage clearance while upright and clearance at 30 minutes were the only variables that differed significantly between surgical cases and those that resolved spontaneously., Conclusions: Radiotracer clearance with the patient upright and clearance at 30 minutes are more predictive of surgical management than diuresis half-time or differential function for renal units with indeterminate drainage. They should be included in the standard assessment of ureteropelvic junction obstruction., (Copyright © 2017 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose: Radiographic evaluation for prenatal hydronephrosis often includes voiding cystourethrography to ascertain whether vesicoureteral reflux is present. We sought to determine whether use of voiding cystourethrography could be limited to those patients at greatest risk for vesicoureteral reflux. We hypothesized that vesicoureteral reflux could be predicted by findings on renal/bladder ultrasonography of hydroureter, renal dysmorphia and/or duplication., Materials and Methods: We reviewed the records of patients with prenatal hydronephrosis who underwent initial postnatal ultrasonography and voiding cystourethrography during a 3-year period. The presence of vesicoureteral reflux on voiding cystourethrogram was correlated to ultrasound findings, including hydronephrosis grade, presence of hydroureter, renal dysmorphia or duplication, with ultrasound considered positive for any of the latter 3 findings., Results: Of 262 patients 47 (18%) had vesicoureteral reflux. Ultrasound was positive in 24 of 29 patients (83%) with high grade reflux and 12 of 18 (67%) with low grade reflux. If ultrasonography showed any of the 3 positive findings, the odds ratio of detecting vesicoureteral reflux was 8.07 (95% CI 3.86, 16.87). Using these criteria, among all cases of prenatal hydronephrosis 5 (2%) with high grade vesicoureteral reflux and 6 (2%) with low grade reflux would have been missed. Among the 47 cases of reflux overall 5 of 29 high grade (17%) and 6 of 18 low grade cases (33%) would have been missed., Conclusions: By using ultrasonography criteria of hydroureter, duplication and renal dysmorphia for patients with prenatal hydronephrosis, vesicoureteral reflux can be detected more specifically. Using our criteria, 165 of 262 voiding cystourethrograms (63%) could have been avoided in patients with prenatal hydronephrosis during a 3-year period. Reducing these evaluations may decrease risks regarding radiation exposure, family anxiety and health care costs., (Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

The upper urinary tract forms as a consequence of the reciprocal inductive signals between the metanephric mesenchyme and ureteric bud. A clue to the timing of events leading to an abnormality of the upper urinary tract can be the presence also of associated anomalies of internal genitalia since separation of these systems occurs at about the 10th week of gestation. Prenatal sonography has facilitated the detection of urological abnormalities presenting with hydronephrosis. Hydronephrosis suggests obstruction, but by itself cannot be equated with it. Instead, further radiographic imaging is required to delineate anatomy and function. Now, moreover, non-surgical management of CAKUT should be considered whenever possible. Despite the widespread use of prenatal screening sonography that usually identifies the majority of congenital anomalies of the urinary tract, many children still present with febrile urinary tract infection (UTI). Regardless of the etiology for the presentation, the goal of management is preservation of renal function through mitigation of the risk for recurrent UTI and/or obstruction. In the past many children underwent surgical repair aimed at normalization of the appearance of the urinary tract. Today, management has evolved such that in most cases surgical reconstruction is performed only after a period of observation - with or without urinary prophylaxis. The opinions presented in this section are not espoused by all pediatric urologists but represent instead the practice that has evolved at Children's National Medical Center (Washington DC) based significantly on information obtained by nuclear renography, in addition to sonography and contrast cystography.

Purpose: Early pyeloplasty is indicated for ureteropelvic junction obstruction (UPJ) obstructions with reduced differential renal function (DRF) and/or no drainage on diuretic renography (DR). Optimal management of Society of Fetal Urology (SFU) Grades 3 and 4hydronephrosis with preservation of DRF and indeterminate drainage is less straightforward. We review our experience using serial DR to guide the management of kidneys with high-grade hydronephrosis, emphasizing preservation of DRF., Methods: After IRB approval we reviewed the charts of 1398 patients <1-year-old referred for prenatal hydronephrosis. Only patients with SFU Grades 3 and 4 hydronephrosis without ureterectasis were included in the study. Initial evaluation included a baseline DR. Follow-up included DR or ultrasound (US)., Results: 115 patients (125 kidneys) were eligible for study inclusion. 27 kidneys underwent early surgery (median 64 days) due to reduced DRF and/or severely impaired drainage. 98 kidneys were initially observed. Of these, 21 underwent delayed surgery (median 487 days) due to worsening drainage. Only 2 patients had an irreversible decrease in DRF of >5%. 77 kidneys demonstrated improved drainage and stable DRF. Comparison of observation (n = 77) and surgery groups (n = 48) revealed more kidneys with SFU Grade 3 hydronephrosis in the observation group (p = 0.0001)., Conclusion: Infants with Grades 3 and 4 hydronephrosis and preserved DRF may be safely followed with serial DR. Patients with SFU Grade 4 hydronephosis are more likely to require surgery. Worsening drainage on serial DR is a useful indicator for surgical intervention which limits the number of pyeloplasties while preserving DRF., (Copyright © 2011 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)