Evaluation of Urinary Tract Dilation Classification System for Grading Postnatal Hydronephrosis

How can we measure the renal pelvic anteroposterior diameter in postnatal isolated hydronephrosis?

INTRODUCTION

The anteroposterior diameter (APD) of the renal pelvis is a commonly used ultrasound parameter in the evaluation and management of hydronephrosis. It has been established that an APD value associated with pyeloplasty is around 25 mm. Some believe the APD should be measured at the innermost part of the renal pelvis while others suggest that it should be done at the renal contour. However, there is no consensus on the optimal APD measurement technique including whether it should be measured supine or prone. This study compared six different techniques of APD measurements, in both supine and prone positions, and further evaluated their association with pyeloplasty.

METHODS

Data was obtained by retrospectively reviewing patients' charts that had initial high-grade hydronephrosis (HGH) from 2008 to 2014. We recorded the patients' demographics, ultrasound data and management choice. In the mid-renal transverse plane, the APD was measured by 2 blinded investigators, at the intra-renal, renal contour and extra-renal regions of the renal pelvis in supine and prone positions (Figure A). We compared the six APD measurements based on the outcome of management (pyeloplasty vs. conservative management). The ROC curve obtained was then used to assess the ability of various APD measurements in predicting surgical intervention. The cutoff value chosen that predicts pyeloplasty was the lowest diameter with 100% specificity.

RESULTS

We included 129 patients (134 renal units). Forty-four renal units (42 patients) underwent pyeloplasty whereas 90 renal units (87 patients) were managed conservatively. Patients' demographics were grouped by both SFU grade and clinical outcome. Regardless of grade, the APD measurements were different in all 6 techniques. All APD measurement techniques showed good inter-rater reliability. Based on the ROC curve, all APD measurements were associated with pyeloplasty with an AUC from 0.89 to 0.91. The supine extra-renal APD measurement of 24 mm was the most sensitive cutoff value. The cutoff values ranged from 18 to 27 mm when including patients from all grades of hydronephrosis. The median APD measurements were significantly less for SFU grade 3 than grade 4 hydronephrosis in all positions (P < 0.001 for all measurements), yet the predictive cutoff value of 24 mm for the supine extra-renal was similar for both grades.

CONCLUSION

APD measurements differ based on the technique, but they are all equally associated with the clinical outcome of pyeloplasty. The inter-rater reliability of all techniques were excellent. Though the median APD measurements are smaller in SFU grade 3, it appears that the cutoff for a predictive renal pelvic APD does not differ between SFU grades 3 and 4 for the supine extra-renal technique. We conclude that the technique for measuring the APD needs to be specified in studies of hydronephrosis and in any grading systems.

Associations, follow up data, and postnatal outcome of antenatally diagnosed Urinary Tract Dilatation - Five-year single tertiary center experience from South India

BACKGROUND

Urinary tract dilatations (UTD) are frequently diagnosed during Mid-Trimester Anomaly Scan (MTAS), at which time, given their variable progression and heterogeneous classification systems, offering suitable counsel to the couple is challenging.

OBJECTIVE

Based on postnatal data, we aimed to guide parental counseling, and further evaluation of UTD diagnosed at MTAS. Specifically, the utility of multi-disciplinary UTD classification system was tested.

METHODS

A retrospective observational study of all UTDs included from five years (2015-2020) MTAS register. The multi-disciplinary UTD classification system was used for antenatal/postnatal UTD categorization. Follow-up data were obtained from case records until the current age of children (2-6 years).

RESULTS

Out of 527 fetal abnormalities, 103 had UTD at MTAS. Based on the third-trimester ultrasound, 49 were low-risk UTD A1, and 44 were increased-risk UTD A2-3 (including the nineteen UTD A1 at MTAS worsened to A2-3 by third-trimester). On postnatal follow-up of UTD A1 and A2-3, respectively, neonatal UTD P2/P3 was seen in 2% and 40.9%; complete spontaneous resolution was seen in 79.5% and 43.18%; none and 22.7% underwent surgical intervention; persistent P2/P3 UTD were seen on follow-up in 2% and 4.5% (excluding those who needed surgery); impaired renal function was seen in none and 36.3%, and recurrent UTI in 8.1% and 34.09%. The subgroup with progressive UTD (from A1 to A2-3 by third-trimester ultrasound) formed 43% of the final UTD A2-3 category. Among these 19 cases, surgical intervention was performed in eight (42%); impaired renal function was seen in 7 cases (36.8%), and recurrent UTI was seen in eight (42%).

DISCUSSION

Given the diverse classification systems for UTD, ours is the second Indian data proving the prognostic utility of multi-disciplinary UTD classification system, specifically at third trimester scan, based on postnatal outcome. In contrast to published guidelines, our data suggests follow-up for renal pelvis anteroposterior diameter (APD) of 4-7 mm at MTAS, as some may worsen. Similar progression has been noted in other Indian studies, but the classification systems are different. Contrary to the published literature, we could not suggest a renal APD cut-off as a single criterion to predict surgical intervention. Significant limitations are retrospective observational design and multiple sonographers.

CONCLUSION

Our data helps guide parental counseling and further evaluation for UTD diagnosed at MTAS. The multi-disciplinary Consensus UTD Classification system, was helpful in prognostication.

Application of the postnatal urinary tract dilation classification system to predict the need for surgical intervention among neonates and young infants

PURPOSE

The aim of this study was to validate the postnatal urinary tract dilation (UTD) classification system by correlating it with the need for surgical intervention.

METHODS

Young infants who underwent ultrasound (US) examinations for prenatal hydronephrosis were retrospectively identified. The kidney units (KUs; right, left, or bilateral) were graded from UTD P0 (very low risk) to P3 (high risk) based on seven US criteria from the UTD system. Surgery-free survival curves were constructed using the Kaplan-Meier method. Univariable and multivariable Cox proportional-hazards regression analysis clustered by patients was performed. Interobserver agreement was analyzed using the weighted kappa coefficient.

RESULTS

In total, 504 KUs from 336 patients (mean age, 18.3±15.9 days; range, 1 to 94 days; males, n=276) were included, with a median follow-up of 24.2 months. Fifty-eight KUs underwent surgical intervention. Significant differences were observed among the Kaplan-Meier curves stratified into UTD groups (P<0.001). The presence of anterior-posterior renal pelvic diameter ≥15 mm (hazard ratio [HR], 8.602; 95% confidence interval [CI], 1.558 to 43.065), peripheral calyceal dilation (HR, 8.190; 95% CI, 1.558 to 43.065), ureteral dilation (HR, 2.619; 95% CI, 1.274 to 5.380), parenchymal thickness abnormality (HR, 3.371; 95% CI, 1.574 to 7.223), bladder abnormality (HR, 12.209; 95% CI, 3.616 to 41.225) were significantly associated with the occurrence of surgery. The interobserver agreement was moderate to almost perfect agreement for US features (κ=0.564-0.898) and substantial for final UTD grades (κ=0.716).

CONCLUSION

The UTD classification system is reliable and appropriately stratifies the risk of surgical intervention.

Outcomes of intermediate-risk hydronephrosis in pediatric patients

PURPOSE

Hydronephrosis is a common antenatal diagnosis and is present in approximately 1-5% of pregnancies. The urinary tract dilation (UTD) classification system was introduced in 2014 and stratifies post-natal hydronephrosis risk into three groups: low-risk (P1), intermediate-risk (P2), and high-risk (P3). Recommendations for P3 hydronephrosis have been established, whereas those for P1 and P2 UTD are often left to the discretion of providers with P1 considered low-grade and less concerning significant pathology. Given the obscure nature of P2 hydronephrosis, we sought to determine the natural history and outcomes of pediatric patients with P2 hydronephrosis within a single institution.

MATERIALS AND METHODS

Children <18 years old diagnosed with hydronephrosis between January 2015 and December 2018 were identified by ICD-9 and ICD-10 codes. Patients with P1 hydronephrosis, P3 hydronephrosis, known vesicoureteral reflux, complex anomalies (ex. Posterior urethral valve), neurological impairments, neurogenic bladder secondary to spinal abnormalities, and <6 months of follow-up were excluded. The development of urinary tract infection (UTI; ≥100 000 CFU/mL of bacterial growth, UA > 10 WBCs/hpf with fever >38C), need for surgical intervention (impaired renal function, worsening hydronephrosis, and/or delayed drainage on diuretic renography), and stability of hydronephrosis were collected retrospectively.

RESULTS

Eighty-seven patients [105 renal units (RU)] were included. Twenty-six patients (30%) were female and 61 (70%) were male. Of the male patients, 30 (49%) of them were circumcised. The median age at initial evaluation was 1 month, and the median duration of follow-up was 13 months. Thirty-four (32%) RU had complete resolution, 24 (23%) improved to P1 hydronephrosis, 33 (31%) remained stable, and 14 (13%) progressed to P3 hydronephrosis. The median duration to resolution and improvement was 8.5 months and 5 months, respectively. Eleven (11%) RU required surgical intervention, 10 of which underwent pyeloplasty, with a median duration to intervention of 9 months. Fifty-five patients (63%) received antibiotic prophylaxis (amoxicillin or sulfamethoxazole-trimethoprim) for a median duration of 5 months. Nine patients (10%) developed a UTI, 3 of which were taking antibiotic prophylaxis at the time of infection.

CONCLUSIONS

Intermediate-risk hydronephrosis diagnosed in the pediatric population will either improve, resolve, or remain stable during 1-year follow-up in 87% of RU. Only 11% of RU required surgical intervention, and 19% of patients developed a UTI in the absence of antibiotic prophylaxis. These findings will assist with counseling parents concerning the importance of follow-up imaging and monitoring for UTI. However, the low risk of surgical intervention is encouraging and should be discussed with the children's caretakers.

Main Pathological Changes of Benign Ureteral Strictures

Objective

To identify the pathological classification of benign ureteral strictures according to the histological features and explore the relationship between various pathological types and inflammatory cells, fibroblasts, and collagen.

Patients and Methods

Thirty one specimens from patients diagnosed with ureteral strictures between 2013 and 2021 were included and classified according to the histopathological characteristics. The number of fibroblasts and inflammatory cells was counted, and the proportion of type I and type III collagen in ureteral stricture tissues was detected by picrosirius red staining.

Results

We identified three types of benign ureteral strictures in 31 specimens: inflammatory cell infiltration (n = 10, 32%), fibroplasia (n = 14, 45%), and hyalinization (n = 7, 23%), with significant differences in obstruction history and hydronephrosis grades among the three types. The number of inflammatory cells (lymphocytes, neutrophils and eosinophils) was significantly lower in hyalinization ureteral strictures than in the other two types (p &lt; 0.05). The number of foreign-body giant cells associated with foreign-body reactions increased significantly in suture-induced ureteral strictures (p &lt; 0.05). Fibroplasia type had the largest number of fibroblasts, whereas the other two types had smaller numbers. The results of type I and III collagen analysis showed that type I and III collagen were the most abundant in hyalinization among all ureteral stricture types (p &lt; 0.05). Compared to ureteral strictures, the content of type I and III collagen in atresia increased significantly (p &lt; 0.05).

Conclusion

Common pathological types of benign ureteral strictures include inflammatory cell infiltration, fibroplasia, and hyalinization. Changes in type I and III collagen, inflammatory cells, and fibroblasts in different pathological types may be related to the progression of ureteral strictures.

2021 update on the urinary tract dilation (UTD) classification system: clarifications, review of the literature, and practical suggestions

In 2014, a multidisciplinary consensus on the classification of pre- and postnatal urinary tract dilation (UTD classification) was developed. Its goal was to provide a standardized system for evaluating and reporting urinary tract dilation both in the prenatal and postnatal periods. In this review, we summarize insights learned from the implementation of the UTD classification system since its inception, providing clarifications on common points of confusion. In addition, we review current literature in the clinical validation of the UTD classification system to provide credence for its use in managing fetuses and children with urinary tract dilation.

Postnatal urinary tract dilatation classification: improvement of the accuracy in predicting kidney injury

BACKGROUND

The grading of urinary tract dilatation (UTD) on postnatal sonography is a fundamental step to establish rational management for infants with antenatal hydronephrosis (ANH). The aim of this study was to compare the prediction accuracy of UTD grading systems for relevant clinical outcomes. In addition, we propose a refinement of the UTD classification by adding quantitative measurements and evaluate its impact on accuracy.

METHODS

Between 1989 and 2019, 447 infants diagnosed with isolated AHN were prospectively followed. The events of interest were surgical interventions and kidney injury. Comparison of performance of the grading systems and the impact on the accuracy of a modified UTD classification (including the size of the kidney parenchyma) was assessed by the area under the receiver-operating characteristic curve (AUC).

RESULTS

Of 447 infants, 131 (29%) underwent surgical intervention and 26 (5.8%) had developed kidney injury. The median follow-up time was 9 years (IQ range, 7-12 years). The performance for detecting the need for surgical intervention was excellent for all grading systems (AUC > 0.90). However, for predicting kidney injury, the modified UTD classification exhibited significant improvement in accuracy (AUC = 0.913, 95%CI, 0.883-0.937) as compared with UTD classification (AUC = 0.887, 95%CI, 0.854-0.915) (P = 0.027).

CONCLUSIONS

Our study confirms that the hydronephrosis grading systems provide excellent accuracy in discriminating patients who need surgical intervention among infants with AHN. Our findings suggest that the inclusion of kidney parenchymal thickness to UTD classification might increase the accuracy for predicting infants who may develop kidney injury. A higher resolution version of the Graphical abstract is available as Supplementary information.

Urinary Tract Dilation in the Fetus and Neonate

Urinary tract dilation (UTD), previously known as hydronephrosis, is the most common congenital condition identified on prenatal ultrasonography. UTD can be physiologic and resolve spontaneously or can be caused by various congenital anomalies of the urinary tract, which can lead to renal failure if not treated properly. In 2014, a multidisciplinary consensus group established UTD definitions, a classification system, and a standardized scheme for perinatal evaluation. Various imaging modalities are available to help diagnose the cause of UTD in fetuses and neonates and to help identify those patients who may benefit from fetal or early postnatal intervention. In this article, we will review the diagnosis and quantification of antenatal and postnatal UTD based on the UTD classification system, outline the imaging studies available to both evaluateUTD and determine its cause, briefly review the most common causes of UTD in the fetus and neonate, outline management strategies for UTD including the role for fetal intervention and prophylactic antibiotics, and report on the outcome and prognosis in patients with UTD.

Comparison of Urinary Tract Dilatation and Society of Fetal Urology systems in the detection of vesicourethral reflux and renal scar

Purpose

The presence and degree of hydronephrosis is very important in the management of many diseases of the urinary tract. In this study, we aim to compare the sensitivity and specificity of 2 classification systems that are used for hydro-nephrosis grading in ultrasound, for reflux and scar detection. The classification systems were the Society of Fetal Urology (SFU) and Urinary Tract Dilatation (UTD).

Material and methods

Ultrasounds and dimercaptosuccinic acid scintigraphies (DMSA) of all patients who underwent voiding cystourethrogram (VCUG) due to urinary tract infection were examined retrospectively. DMSA was accepted for scar detection and VCUG for reflux detection as reference methods. SFU classification was used for hydronephrosis in ultrasound reports, and UTD classification was made over the reports. Sensitivity, specificity, and positive and negative predictive values of UTD and SFU classification systems for reflux and scar detection were calculated, and these 2 systems were compared.

Results

103 (39%) of the patients were male and 162 (61%) were female. Pathologies were detected in 192 (35%) of 530 kidneys in ultrasound. In 110 (42%) of the children, reflux was detected in VCUG. Scars in DMSA were detected in only 16% (44) of 266 kidneys. Sensitivity, positive and negative predictive values of the UTD classification system were statistically significantly higher than the SFU system for scar and reflux detection (p < 0.01).

Conclusions

If we use the UTD system in ultrasounds of patients with urinary tract infections, children reported as UTD 0 may not need VCUG, which reduces radiation exposure to children and the cost of the diagnostic interventions.

A Retrospective Analysis to Evaluate Role of the New UTD Classification System in Prenatal Prediction of Severity and Postnatal Outcome in Antenatally Diagnosed Urinary Tract Dilatation Abnormalities

Background/Purpose of the Study

Foetal urinary tract dilation (UTD) abnormalities affect 1-5% of all pregnancies. However, exact incidence is difficult to estimate because of different terminologies used to define the condition and different grading systems to define its severity antenatally as well as postnatally worldwide. In order to overcome this problem, the new UTD classification system has been introduced in the year 2014 so as to have universal approach for diagnosis and management of UTD globally. Indian data about clinical utility of the UTD classification system and its role in prenatal prediction of severity of renal disease are lacking. The present study aims to investigate clinical utility of new UTD classification system in foetal UTD abnormalities and to evaluate the role of UTD classification system in antenatal prediction/prognostication of severity of UTD abnormalities.

Methods

We conducted a single-centre retrospective study between April 2014 and January 2017, which included 70 infants with antenatally diagnosed UTD delivered in our hospital and managed in our paediatric unit postnatally. Pre- and postnatal ultrasound findings were noted, and UTD-A and UTD-P classification were applied retrospectively in all cases as per criteria defined in the new UTD classification. Postnatal outcome in all cases was evaluated in terms of need for immediate postnatal urosurgical intervention, presence of persistent UTD pathology and severity of renal impairment in relation to their pre- and postnatal UTD A and P risk categories.

Results

None from UTD A1 risk group in the last prenatal scan showed significant postnatal UTD abnormality. In contrast to this, UTD A2-3 risk group in the last prenatal scan had persistent postnatal UTD pathology in 70% cases. All infants with abnormal postnatal UTD diagnosis were identified prenatally as UTD A2-3 (high risk). Nine infants (12.8%, n = 70) who needed urosurgical intervention postnatally were categorised as UTD A2-3 prenatally and UTD P3 postnatally.

Conclusion

We found increased frequency of complications and urosurgical interventions in all infants with antenatal UTD A2-3 grades in the last prenatal scan in comparison with those with UTD A1 grades who showed complete resolution (100%) postnatally. Antenatal UTD classification may be useful in antenatal prediction and prognostication of postnatal severity, especially in high-risk cases (i.e. UTD A2-3).

Comparative outcomes of flexible ureteroscopy and mini-percutaneous nephrolithotomy for pediatric kidney stones larger than 2 cm

OBJECTIVES

To compare the outcomes of flexible ureteroscopy and mini-percutaneous nephrolithotomy for pediatric kidney stones larger than 2 cm and to show the learning curves for the two procedures.

METHODS

A prospectively managed database containing pediatric patients with kidney stones larger than 2 cm from June 2014 to October 2019 was analyzed. The primary outcomes were the efficacy and safety of flexible ureteroscopy and mini-percutaneous nephrolithotomy. Data on patient demographics, treatment details, stone-free rate, and complication rate were collected and compared. Learning curves were generated to estimate the effect of the surgeon's experience on surgical outcomes.

RESULTS

The final analysis included 113 pediatric patients who underwent surgery for kidney stones on a total of 126 sides. The stone-free rates for mini-percutaneous nephrolithotomy and flexible ureteroscopy were 80.9% (34/42) and 79.7% (67/84), respectively (P = 0.19). The complication rates for mini-percutaneous nephrolithotomy and flexible ureteroscopy were 52.5% (21/40) and 27.4% (27/73), respectively (P = 0.01). When stone mass was considered, the stone-free rates for mini-percutaneous nephrolithotomy and flexible ureteroscopy for stones with a high mass (>5000 HU*cm² ) were 83.3% (20/24) and 55.5% (10/18), respectively (P = 0.04). The learning curves showed that the stone-free rates for both mini-percutaneous nephrolithotomy and flexible ureteroscopy increased with the accumulation of cases. A higher stone-free rate could be achieved after approximately 20 mini-percutaneous nephrolithotomy cases and after approximately 50 flexible ureteroscopy cases.

CONCLUSIONS

Flexible ureteroscopy has an acceptable stone-free rate and a lower complication rate than mini-percutaneous nephrolithotomy when treating pediatric kidney stones larger than 2 cm. Mini-percutaneous nephrolithotomy is more applicable to stones with a high mass. The stone-free rates achieved after both mini-percutaneous nephrolithotomy and flexible ureteroscopy could be improved with number of cases accumulated.

Nomograms predicting the outcomes of endoscopic treatments for pediatric upper urinary tract calculi

OBJECTIVES

To demonstrate the efficacy and safety of mini-percutaneous nephrolithotomy, micro-percutaneous nephrolithotomy, and flexible ureteroscopy for pediatric upper urinary tract calculi and to develop nomograms predicting surgical outcomes.

METHODS

A prospectively managed database containing children who were diagnosed with upper urinary tract calculi and treated with mini-percutaneous nephrolithotomy, micro-percutaneous nephrolithotomy, and flexible ureteroscopy between June 2014 and April 2019 was analysed. Patient demographics, intraoperative data, stone characteristics, stone-free rate, and complication rate were analysed and compared. Nomograms predicting the postoperative stone-free rate and complication rate were established based on predictors, and internal validation was performed. Calibration curves and decision curves were generated to assess the predictive efficacy and clinical benefit.

RESULTS

Forty-three children underwent mini-percutaneous nephrolithotomy on 56 sides in 47 operations, 30 children underwent micro-percutaneous nephrolithotomy on 30 sides in 30 operations, and 275 children underwent flexible ureteroscopy on 320 sides in 288 operations. The stone-free rates were 88.5% (282/320) for flexible ureteroscopy, 89.3% (50/56) for mini-percutaneous nephrolithotomy, and 90.0% (27/30) for micro-percutaneous nephrolithotomy (P = 0.94). And the complication rates were 19.8% (57/288), 36.2% (17/47), and 33.3% (10/30), respectively (P = 0.02). Nomograms based on stone characteristics, operation duration, and the physical condition of the child were shown to have good discrimination and calibration. The area under the curve of the models was 81% for stone-free rate and 73% for complication rate. The calibration curves showed that the nomogram might underestimate the probability of stone-free rate when the threshold was below 82% and might overestimate the risk of complication rate when the threshold was over 25%. The decision curves demonstrated that the Capital Medical University nomograms improved clinical risk prediction against threshold probabilities of stone-free rate ≤20% and complication rate ≤10%.

CONCLUSIONS

Both the percutaneous nephrolithotomy and flexible ureteroscopy procedures could have acceptable stone-free rates when treating pediatric stones. The Capital Medical University nomograms performed well in helping to predict stone-free and complication rates.

Postnatal management of children with antenatal hydronephrosis

Background

Postnatal management of infants with antenatal hydronephrosis (ANH) is still one of the most controversial issues. The majority of infants with ANH are asymptomatic with only few children who develop renal insufficiency. Thus, the biggest challenge for pediatric urologists is to distinguish children who will require further investigations and possible intervention prior to the development of symptoms, complications or renal damage in a cost effective manner without exposing them to the hazards of unnecessary investigations.

Main body

In this review article, literature on ANH were reviewed to present the current suggestions, recommendations, guidelines and their rational for postnatal management of ANH. It is agreed that a large portion of infants with ANH will improve; thus, the protocol of management is based mainly on observation and follow-up by ultrasound to detect either resolution, stabilization or worsening of hydronephrosis. The first 2 years of life are critical for this follow-up as the final picture is mostly reached during that period. Advanced imaging using voiding cystourethrography or renal scintigraphy are required for children at risk. Then, surgical intervention is selected only for a subgroup of these infants who showed worsening of hydronephrosis or renal function.

Conclusions

The protocol of management is based mainly on observation and follow-up by US to detect either resolution, stabilization or worsening of hydronephrosis. Postnatal evaluation should be performed for any neonate with a history ANH at any stage during pregnancy even if it was resolved during third trimester. Exclusion of UTI should be performed by urinalysis for all cases followed by urine culture if indicated. Serum creatinine should be performed especially in patients with bilateral ANH. US is the initial standard diagnostic imaging technique. Other imaging modalities like VCUG and nuclear renal scans may be required according to the results of the US evaluation. The most important items in decision making are the presence of bilateral or unilateral hydronephrosis, presence or absence of hydroureter, presence of lower urinary tract obstruction and degree of hydronephrosis on the initial postnatal US. Then an intervention is selected only for a subgroup of these patients who showed deterioration in renal function or degree of hydronephrosis or were complicated by UTIs. All these recommendations are based on the available literature. However, management of ANH is still a controversial issue due to lack of high evidence-based recommendations. Randomised controlled studies are still needed to provide a high level evidence for different aspects of management.

Influence of Body Mass Index on the Surgical Outcomes of Flexible Ureteroscopy for Pediatric Upper Urinary Tract Aalculi-A Single Surgeon Experience

OBJECTIVE

To examine the association between body mass index (BMI) and surgical outcomes of flexible ureteroscopy (FURS) for pediatric upper urinary tract calculi and to estimate the influence of BMI percentile on the learning curve of pediatric FURS.

MATERIALS AND METHODS

We reviewed our prospectively maintained database containing children who had kidney or ureteral stones from June 2014 to April 2019. We calculated BMI and plotted it on the Centers for Disease Control and Prevention growth chart for sex and age to estimate BMI percentile. Patient demographics, intraoperative data, stone characteristics, stone-free rate (SFR), and complication rate (CR) were analyzed. Learning curves stratified by BMI percentile groups were generated.

RESULTS

The final analysis included 161 children, of whom 63 (39.1%) had upper body weight percentile (UBW), 64 (39.8%) had normal body weight percentile (NBW), and 34 (21.1%) had lower body weight percentile (LBW). The median stone burden of the 3 groups were 1.14 (IQR 0.50-3.41), 1.13 (IQR 0.70-3.14), and 0.95 (IQR 0.50-1.77), respectively (P = .17). The SFRs were 90.5% (57/63) in the UBW group, 81.2% (52/64) in the NBW group and 70.6% (24/34) in the LBW group (P = .04). The CRs were 15.9% (10/63), 21.9% (14/64), and 29.4% (10/34), respectively (P = .29). The learning curves showed that the SFR of FURS could be improved after about 100 cases. And decreasing BMI could steepen the learning curve of SFR.

CONCLUSIONS

BMI is associated with the SFR of FURS. LBW children had the lowest SFR compared to UBW and NBW children. Lower BMI percentile makes the success of FURS more challenging.

Does the presence of non-refluxing hydroureter impact the management and outcome of high-grade hydronephrosis?

INTRODUCTION

We aimed to evaluate the impact of non-refluxing hydroureter on the initial management of high-grade hydronephrosis (HGH) management. Moreover, we evaluated the occurrence of febrile urinary tract infection (fUTI) and surgical intervention for conservatively managed units.

METHODS

Patients' charts with postnatal hydronephrosis from 2008-2014 were retrospectively reviewed. We included patients who presented in the first year of life. All included patients had HGH (Society of Fetal Ultrasound [SFU] grades 3 and 4) and all were non-refluxing using voiding cystourethrogram (VCUG). We categorized renal units into two groups: with hydroureteronephrosis (HUN) and without hydroureter (isolated hydronephrosis [IH]). We recorded the initial management. We evaluated the impact of non-refluxing hydroureter on hydronephrosis fate, fUTI, and change to surgery for those managed conservatively.

RESULTS

We included 169 patients (180 units). IH was diagnosed in 146 units (137 patients), whereas 34 units (32 patients) had HUN. Median followup was 42.9 months. A total of 25.3% (37/146) of IH units had initial surgical management in comparison to 5.1% (2/34) of HUN units (p=0.01). During conservative management, nine HUN patients (30%) and 11 IH patients (10.7%) experienced fUTI (p=0.009). Surgical intervention after failed conservative management was indicated for 12 IH units (11%) and six HUN units (18.8%) (p=0.25). Anteroposterior diameter (APD) worsening was significantly associated with the change to surgery in IH group (p=0.003). More than half (52.3%) of IH units resolved during conservative management in comparison to 18.7% of HUN (p<0.001). HUN had longer time to resolution (log rank=0.004).

CONCLUSIONS

IH units had more initial surgical interventions. The fUTI rate was much higher in association with dilated ureter even under antibiotic coverage. HUN was associated with less and slower resolution rate.

The association of postnatal urinary tract dilation risk score with clinical outcomes

BACKGROUND

There are limited data on the predictive value of the consensus urinary tract dilation (UTD) score with respect to subsequent clinical diagnoses. We sought to define the relationship between postnatal UTD risk score and clinical outcomes during childhood.

METHODS

Complete ultrasound image sets from a random selection of infants aged 0-90 days undergoing initial ultrasound at a single institution for prenatal hydronephrosis between 2012 and 2014 were assigned a UTD score by 1 pediatric urologist and 1 pediatric radiologist. Urinary tract dilation risk score was analyzed for association with a composite outcome comprising urinary tract infection, vesicoureteral reflux (VUR), ureteropelvic junction obstruction, non-refluxing megaureter (NRM), ureterocele, bladder outlet obstruction (BOO), and chronic kidney disease. Surgical intervention and resolution of UTD were evaluated separately. Descriptive and survival analyses were performed.

RESULTS

Urinary tract dilation scores for 494 subjects were P0 in 23.5%, P1 in 26.5%, P2 in 23.5%, and P3 in 26.5%. Seventy-four percent were male. Median age at initial imaging was 28 days; median follow-up was 19.8 months. The composite outcome occurred in 138 of 494 patients (27.9%) and varied significantly (p < 0.001) by UTD score: 11.2% for P0, 10.7% for P1, 29.3% for P2, and 58.8% for P3. On survival analysis (Summary Figure), higher UTD grade was significantly associated with the composite outcome (hazard ratio for P3 vs. P0 was 7.4 [95% CI: 3.44-15.92, p < 0.001]). Urinary tract infection and VUR diagnosis varied by UTD score (p = 0.03 and p < 0.001, respectively). Ureteropelvic junction obstruction was diagnosed (based on MAG3 results) in 6.3% of patients, 84% of whom were P3. Non-refluxing megaureter was diagnosed in 7.7%. Ureterocele and BOO were uncommon (1.4%, and 0.6%, respectively). Surgical intervention was also associated with UTD risk, with 46% of P3 undergoing surgery vs. 1% of P0, 1% of P1, and 6% of P2 (p < 0.001). Resolution of UTD occurred in 41% (median 10.1 months) and varied significantly by UTD risk (p < 0.001).

DISCUSSION

Urinary tract dilation risk score is associated with clinical events, although ascertainment bias may influence some of the differences in outcomes, particularly for VUR, because VCUG utilization varied by the UTD group. The lack of any significant difference in outcomes between patients with UTD P0 versus P1 suggests that the P1 category could be eliminated as it does not meaningfully distinguish between outcome risk.

CONCLUSIONS

Higher UTD risk scores are strongly associated with genitourinary diagnoses during the first two years of life.

Mild-to-moderate renal pelvis dilatation identified during pregnancy and hospital admissions in childhood: An electronic birth cohort study in Wales, UK

BACKGROUND

Chronic kidney disease (CKD) is a growing contributor to the global burden of noncommunicable diseases. Early diagnosis and treatment can reduce the severity of kidney damage and the need for dialysis or transplantation. It is not known whether mild-to-moderate renal pelvis dilatation (RPD) identified at 18-20 weeks gestation is an early indicator of renal pathology. The aim of this follow-up to the Welsh Study of Mothers and Babies was to assess the risk of hospital admission in children with mild-to-moderate antenatal RPD compared with children without this finding. We also examined how the natural history of the RPD (whether the dilatation persists in later pregnancy or postpartum) or its characteristics (unilateral versus bilateral) changed the risk of hospital admission.

METHODS/FINDINGS

This population-based cohort study included singleton babies born in Wales between January 1, 2009, and December 31, 2011 (n = 22,045). We linked ultrasound scan data to routinely available data on hospital admissions from the Patient Episode Database for Wales (PEDW). The outcome was a hospital admission for urinary tract causes (defined by an expert study steering group) in the first three years of life. We used Cox regression to model time to first hospital admission, according to whether there was evidence of RPD at the fetal anomaly scan (FAS) and/or evidence of dilatation in later investigations, adjusting for other predictors of admission. We used multiple imputation with chained equations to impute values for missing data. We included 21,239 children in the analysis. The risk of at least one hospital admission was seven times greater in those with RPD (n = 138) compared with those without (n = 21,101, conditional hazard ratio [cHR] 7.23, 95% confidence interval [CI] 4.31-12.15, p < 0.001). The risk of hospital admission was higher in children with RPD at the FAS and later dilatation (cHR 25.13, 95% CI 13.26-47.64, p < 0.001) and in children without RPD at the FAS who had later dilatation (cHR 62.06, 95% CI 41.10-93.71, p < 0.001) than in children without RPD (n = 21,057). Among children with RPD at the FAS but no dilatation in later pregnancy or postpartum, we did not find an association with hospital admissions (cHR 2.16, 95% CI 0.69-6.75, p = 0.185), except when the initial dilatation was bilateral (cHR 4.77, 95% CI 1.17-19.47, p = 0.029). Limitations of the study include small numbers in subgroups (meaning that these results should be interpreted with caution), that less severe outcomes (such as urinary tract infections [UTIs] managed in the community or in outpatients) could not be included in our analysis, and that obtaining records of radiological investigations later in pregnancy and postpartum was challenging. Our conclusions were consistent after conducting sensitivity analyses to account for some of these limitations.

CONCLUSIONS

In this large population-based study, children with RPD at the FAS had higher rates of hospital admissions when there was persistent dilatation in later pregnancy or postpartum. Our results can be used to improve counselling of parents and develop care pathways for antenatal screening programmes, including protocols for reporting and further investigation of RPD.

Value of renal pelvic diameter and urinary tract dilation classification in the prediction of urinary tract anomaly

BACKGROUND

The aim of this study was to identify the cut-offs of postnatal anteroposterior renal pelvic diameter (APRPD), according to the urinary tract dilation (UTD) classification system, to identify the predictors of final diagnosis of UTD and the need for surgery.

METHODS

A total of 260 infants (336 renal units) with prenatally detected UTD were prospectively evaluated on serial ultrasonography by the same radiologist. Additional voiding cystourethrography and scintigraphy was done according to the clinical algorithm.

RESULTS

Prenatal and postnatal APRPD in patients with transient dilation were significantly lower than in those with urinary tract anomalies (UTA). On follow up, the slope of decrease in APRPD was significantly higher in transient dilation compared with UTA. APRPD 10 mm at first-month ultrasonography, predicted UTA with a sensitivity of 83.1%, and specificity of 71.1%. On multivariate analysis the likelihood of surgical intervention and final diagnosis were predicted independently by the UTD system risk group.

CONCLUSIONS

Careful ultrasonography evaluation can avoid unnecessary testing in patients with transient or clinically insignificant dilation. The UTD classification system is valid for evaluation of postnatal hydronephrosis and is reliable in predicting the need for surgical intervention.

A Predictive Model of Postnatal Surgical Intervention in Children With Prenatally Detected Congenital Anomalies of the Kidney and Urinary Tract

The aim of this study was to identify predictive factors and develop a model to assess individualized risk of postnatal surgical intervention in patients with antenatal hydronephrosis. This is a retrospective cohort study of 694 infants with prenatally detected congenital anomalies of kidney and urinary tract with a median follow-up time of 37 months. The main event of interest was postnatal surgical intervention. A predictive model was developed using Cox model with internal validation by bootstrap technique. Of 694 patients, 164 (24%) infants underwent surgical intervention in a median age of 7.8 months. Predictors of the surgical intervention in the model were: baseline glomerular filtration rate, associated hydronephrosis, presence of renal damage and the severity of renal pelvic dilatation. The optimism corrected c statistic for the model was 0.84 (95%CI, 0.82-0.87). The predictive model may contribute to identify infants at high risk for surgical intervention. Further studies are necessary to validate the model in patients from other settings.

Society for Fetal Urology Classification vs Urinary Tract Dilation Grading System for Prognostication in Prenatal Hydronephrosis: A Time to Resolution Analysis

PURPOSE

The Urinary Tract Dilation grading system for prenatal hydronephrosis was introduced to address potential shortcomings of the Society for Fetal Urology classification. Hydronephrosis resolution is an important patient outcome and is frequently discussed during family counseling. We compared these 2 grading systems and their ability to predict time to hydronephrosis resolution.

MATERIALS AND METHODS

We prospectively screened 855 patients with prenatal hydronephrosis due to ureteropelvic junction obstruction-like hydronephrosis, nonrefluxing primary megaureter or vesicoureteral reflux between 2009 and 2015. Of the patients 454 were excluded due to surgery, late referral, absence of postnatal dilatation or presence of other anomalies, resulting in 401 eligible patients (of whom 81% were male) to be included for analyses. Hydronephrosis grades collected at baseline and last followup were compared to identify resolution trends through time. Hydronephrosis resolution was defined as renal pelvis anteroposterior diameter 10 mm or less at last followup. Time to resolution was analyzed using Cox proportion regression.

RESULTS

Of 401 patients 328 (82%) had resolution during a mean ± SD followup of 24 ± 18 months (maximum 107). Cumulative resolution rate at 3 years was 98% for Society for Fetal Urology grade I hydronephrosis, 87% for grade II, 76% for grade III and 57% for grade IV. The 3-year hydronephrosis resolution rate was 90% for Urinary Tract Dilation postnatal grade 1 (low risk), 81% for grade 2 (intermediate risk) and 71% for grade 3 (high risk).

CONCLUSIONS

Patients with distinctive baseline hydronephrosis grades (classified by Society for Fetal Urology or Urinary Tract Dilation system) had significantly different resolution times for hydronephrosis (p <0.001). Counseling families regarding time to resolution of prenatal hydronephrosis should remain the same whether using Society for Fetal Urology or Urinary Tract Dilation grading system.

Classification of pediatric urinary tract dilation: the new language

The multidisciplinary consensus on the classification of prenatal and postnatal urinary tract dilation (UTD classification system) was created to unify the language used to describe urinary tract dilation on antenatal and postnatal ultrasound examinations and thereby facilitate communication among providers and improve outcomes research. The background and new classification system are described in this review, with imaging examples.

Six of one, half a dozen of the other: A measure of multidisciplinary inter/intra-rater reliability of the society for fetal urology and urinary tract dilation grading systems for hydronephrosis

INTRODUCTION

The urinary tract dilation (UTD) classification system was introduced to standardize terminology in the reporting of hydronephrosis (HN), and bridge a gap between pre- and postnatal classification such as the Society for Fetal Urology (SFU) grading system. Herein we compare the intra/inter-rater reliability of both grading systems.

MATERIALS AND METHODS

SFU (I-IV) and UTD (I-III) grades were independently assigned by 13 raters (9 pediatric urology staff, 2 nephrologists, 2 radiologists), twice, 3 weeks apart, to 50 sagittal postnatal ultrasonographic views of hydronephrotic kidneys. Data regarding ureteral measurements and bladder abnormalities were included to allow proper UTD categorization. Ten images were repeated to assess intra-rater reliability. Krippendorff's alpha coefficient was used to measure overall and by grade intra/inter-rater reliability. Reliability between specialties and training levels were also analyzed.

RESULTS

Overall inter-rater reliability was slightly higher for SFU (α = 0.842, 95% CI 0.812-0.879, in session 1; and α = 0.808, 95% CI 0.775-0.839, in session 2) than for UTD (α = 0.774, 95% CI 0.715-0.827, in session 1; and α = 0.679, 95% CI 0.605-0.750, in session 2). Reliability for intermediate grades (SFU II/III and UTD 2) of HN was poor regardless of the system. Reliabilities for SFU and UTD classifications among Urology, Nephrology, and Radiology, as well as between training levels were not significantly different.

DISCUSSION

Despite the introduction of HN grading systems to standardize the interpretation and reporting of renal ultrasound in infants with HN, none have been proven superior in allowing clinicians to distinguish between "moderate" grades. While this study demonstrated high reliability in distinguishing between "mild" (SFU I/II and UTD 1) and "severe" (SFU IV and UTD 3) grades of HN, the overall reliability between specialties was poor. This is in keeping with a previous report of modest inter-rater reliability of the SFU system. This drawback is likely explained by the subjective interpretation required to assign grades, which can be impacted by experience, image quality, and scanning technique. As shown in the figure, which demonstrates SFU II (a) and SFU III (b), as assigned by a radiologist, it is possible to make an argument that either of these images can be classified into both categories that were observed during the grading sessions of this study.

CONCLUSION

Although both systems have acceptable reliability, the SFU grading system showed higher overall intra/inter-rater reliability regardless of rater specialty than the UTD classification. Inter-rater reliability for SFU grades II/III and UTD 2 was low, highlighting the limitations of both classifications in regards to properly segregating moderate HN grades.

Conversion and reliability of two urological grading systems in infants: the Society for Fetal Urology and the urinary tract dilatation classifications system

BACKGROUND

The urinary tract dilation (UTD) classification system was proposed in 2014.

OBJECTIVE

To evaluate the correspondence and reliability of two US grading systems for postnatal urinary tract dilatation in infants: the Society for Fetal Urology (SFU) and the UTD systems.

MATERIALS AND METHODS

We assessed 180 kidneys in infants younger than 1 year. Four radiologists assessed the kidneys twice using both the SFU system (grades 0 to 4) and the UTD system (grades normal, P1, P2, P3). The SFU system was re-categorized into SFU-A (grades 0, 1-2, 3, 4) and into SFU-B (grades 0-1, 2, 3, 4). The Cohen kappa statistic was used for estimating agreement of both UTD-SFU-A and UTD-SFU-B.

RESULTS

The Cohen kappa was significantly higher between UTD and SFU-B as compared to the UTD and SFU-A (0.75 vs. 0.50, P < 0.001). Intra-observer agreement was similar for the two grading systems (SFU 0.64-0.88 vs. UTD 0.48-0.92, P = 0.050-0.885). SFU grades 2 and 3 showed fair to moderate inter-observer agreement and corresponding UTD grades P1 and P2 showed moderate to substantial agreement. The overall inter-observer agreement was significantly higher for the UTD system than for the SFU system during the first assessment (95% confidence interval [CI]: right kidney, -0.069 to -0.062; left kidney, -0.048 to -0.043).

CONCLUSION

Correspondence between the systems was poor using a recommended re-categorization (SFU-A). An alternative re-categorization (SFU-B) was found to be more appropriate for establishing correspondence between the systems. Both systems were reliable, with good intra- and inter-observer agreement for the assessment of infant kidneys, but the UTD system had better inter-observer agreement.

Inter-rater reliability of the APD, SFU and UTD grading systems in fetal sonography and MRI

INTRODUCTION

Antenatal hydronephrosis (ANH) is frequently detected on screening obstetric ultrasonography. Common ANH grading systems include the anterior-posterior diameter (APD) and the Society for Fetal Urology (SFU) grading system. Recent developments in the management of ANH include the use of fetal magnetic resonance imaging (MRI), and a new grading system - Urinary Tract Dilation (UTD). This study reviewed patients who underwent fetal MRI and ultrasound, and compared the grading systems across these imaging modalities.

MATERIALS AND METHODS

Patients who underwent paired fetal MRI and ultrasound studies between January 2012 and January 2014 were included. Two pediatric urologists and a pediatric radiologist reviewed the studies. Data collected included APD, SFU grade, and UTD grade. Fleiss' kappa statistic determined the inter-rater reliability (IRR) of the SFU and UTD grading within each imaging modality. Intra-class correlation assessed the consistency of the APD measurements.

RESULTS

Forty-seven patients and 88 renal units were evaluated. Median gestational age was 22 weeks. Kappa values of the SFU grading system indicated fair IRR for ultrasound imaging and moderate IRR for MRI imaging, while the UTD grading system reached moderate IRR for both. The IRR of the SFU grading system was improved with the use of MRI, while the UTD grading system was no different. The APD intraclass correlation coefficient improved significantly when measured by MRI. As the ultrasound SFU grade increased, the odds of the MRI SFU grade being scored higher increased by a factor of 3.7. There was no difference between ultrasound and MRI when using the UTD grading system.

DISCUSSION

This study was the first to assess the UTD system in a cohort of patients who underwent paired ultrasound and MRI studies. The results suggested that the UTD system might improve IRR, compared with the SFU system. The use of fetal MRI may improve the IRR of the SFU grading system. It also found that the proportion of SFU grades was affected by the imaging modality, raising the possibility that MRI 'overcalls' the SFU grade, compared with ultrasound. This difference was not observed using the UTD grading system. The most important limitation was the selection bias favoring complex pathology with severe ANH diagnosed at an early gestational age.

CONCLUSIONS

In this unique cohort, the UTD system improved IRR when compared to the SFU grading system. Fetal MRI improved the IRR of the SFU grading system, and improved the APD intraclass correlation. The SFU grading was likely to be higher when assessed by MRI vs ultrasound, but the UTD grade was not affected by the imaging modality.

Associations of Initial Society for Fetal Urology Grades and Urinary Tract Dilatation Risk Groups with Clinical Outcomes in Patients with Isolated Prenatal Hydronephrosis

PURPOSE

There are limited comparative data on the predictive value of the 2 most commonly used classification systems, that is SFU (Society for Fetal Urology) hydronephrosis grades and urinary tract dilatation risk groups, in regard to the future risk of surgical intervention and the development of febrile urinary tract infection. We explored this topic in infants with isolated hydronephrosis.

MATERIALS AND METHODS

After screening 938 patients with prenatal hydronephrosis from 2009 to 2016 we selected 322 patients with ureteropelvic junction obstruction-like hydronephrosis for study. Hydronephrosis grades were prospectively collected at baseline, surgery and last followup. Gender, circumcision status, antibiotic prophylaxis and renal pelvis anteroposterior diameter were captured. The primary outcome was pyeloplasty and the development of febrile urinary tract infection. Comparative analyses between SFU grades/urinary tract dilatation groups and the primary outcome were performed with the Fisher exact and log rank tests.

RESULTS

Mean ± SD age at presentation was 3.3 ± 2.6 months and mean followup was 22 ± 19 months. Pyeloplasty was performed in 32% of patients with SFU III/IV vs 31% with urinary tract dilatation 2/3. The rate of febrile urinary tract infection in patients with SFU III/IV was similar to that in those with urinary tract dilatation group 2/3 (8% vs 10%). Children with SFU III/IV showed a significantly higher rate of surgery than those with SFU I/II (32% vs 2%, p <0.01). Similar findings were seen when using urinary tract dilatation groups to compare patients at low risk (1) vs moderate/high risk (2/3).

CONCLUSIONS

Both grading systems equally allowed for proper risk stratification and prediction of clinical outcomes based on baseline ultrasound. They correctly separated most infants who underwent surgery or in whom febrile urinary tract infection developed from those who could be treated nonsurgically. Use of the new urinary tract dilatation classification should not affect how families of children with isolated hydronephrosis are counseled regarding surgical intervention and the risk of febrile urinary tract infection.