Reliability Assessment of Society for Fetal Urology Ultrasound Grading System for Hydronephrosis

The mayo adhesive probability score predicts postoperative fever and sepsis in retrograde intrarenal surgery

Infectious complications are among the most common and potentially life-threatening morbidities of retrograde intrarenal surgery (RIRS). Few predictive tools on these complications include radiological signs. The Mayo adhesive probability (MAP) score is an image-based scoring system that incorporates two radiological signs: perinephric fat stranding and perinephric fat thickness. Previous studies have suggested an association between these signs and febrile urinary tract infection (UTI) following lithotripsy. This study aimed to evaluate the predictive factors, including the MAP score, for post-RIRS fever and sepsis. A total of 260 patients who underwent 306 RIRS between October 2019 to December 2023 due to renal or upper ureteral stones were included in this retrospective study. Patient demographics, perioperative characteristics, stone factors, radiological signs, and MAP scores were recorded. Multivariate logistic regression analysis was used to evaluate the risk factors associated with postoperative fever and sepsis. Postoperative fever and sepsis occurred in 20.8% and 8.5% of the patients, respectively. On multivariate analysis, female gender, history of recurrent UTI, larger maximal stone diameter, and higher MAP score were independent risk factors for postoperative fever and sepsis. Identifying the risk factors for post-RIRS infectious complications is imperative to providing the proper perioperative management. The MAP score is a promising, easily calculated, image-based scoring system that predicts post-RIRS fever and sepsis.

Automated Society of Fetal Urology (SFU) grading of hydronephrosis on ultrasound imaging using a convolutional neural network

INTRODUCTION

Grading of hydronephrosis severity on postnatal renal ultrasound guides management decisions in antenatal hydronephrosis (ANH). Multiple systems exist to help standardize hydronephrosis grading, yet poor inter-observer reliability persists. Machine learning methods may provide tools to improve the efficiency and accuracy of hydronephrosis grading.

OBJECTIVE

To develop an automated convolutional neural network (CNN) model to classify hydronephrosis on renal ultrasound imaging according to the Society of Fetal Urology (SFU) system as potential clinical adjunct.

STUDY DESIGN

A cross-sectional, single-institution cohort of postnatal renal ultrasounds with radiologist SFU grading from pediatric patients with and without hydronephrosis of stable severity was obtained. Imaging labels were used to automatedly select sagittal and transverse grey-scale renal images from all available studies from each patient. A VGG16 pre-trained ImageNet CNN model analyzed these preprocessed images. Three-fold stratified cross-validation was used to build and evaluate the model that was used to classify renal ultrasounds on a per patient basis into five classes based on the SFU system (normal, SFU I, SFU II, SFU III, or SFU IV). These predictions were compared to radiologist grading. Confusion matrices evaluated model performance. Gradient class activation mapping demonstrated imaging features driving model predictions.

RESULTS

We identified 710 patients with 4659 postnatal renal ultrasound series. Per radiologist grading, 183 were normal, 157 were SFU I, 132 were SFU II, 100 were SFU III, and 138 were SFU IV. The machine learning model predicted hydronephrosis grade with 82.0% (95% CI: 75-83%) overall accuracy and classified 97.6% (95% CI: 95-98%) of the patients correctly or within one grade of the radiologist grade. The model classified 92.3% (95% CI: 86-95%) normal, 73.2% (95% CI: 69-76%) SFU I, 73.5% (95% CI: 67-75%) SFU II, 79.0% (95% CI: 73-82%) SFU III, and 88.4% (95% CI: 85-92%) SFU IV patients accurately. Gradient class activation mapping demonstrated that the ultrasound appearance of the renal collecting system drove the model's predictions.

DISCUSSION

The CNN-based model classified hydronephrosis on renal ultrasounds automatically and accurately based on the expected imaging features in the SFU system. Compared to prior studies, the model functioned more automatically with greater accuracy. Limitations include the retrospective, relatively small cohort, and averaging across multiple imaging studies per patient.

CONCLUSIONS

An automated CNN-based system classified hydronephrosis on renal ultrasounds according to the SFU system with promising accuracy based on appropriate imaging features. These findings suggest a possible adjunctive role for machine learning systems in the grading of ANH.

Clinical and molecular correlation defines activity of physiological pathways in life-sustaining kidney xenotransplantation

Porcine kidney xenotransplantation is accelerating towards clinical translation. However, despite the demonstrated ability of porcine kidneys to remove metabolic waste products, questions remain about their ability to faithfully recapitulate renal endocrine functions after transplantation. Here we analyze xenograft growth and function of two kidney dependent endocrine pathways in seventeen cynomolgus macaques after kidney xenotransplantation from gene edited Yucatan minipigs. Xenograft growth, the renin-angiotensinogen aldosterone-system, and the calcium-vitamin D-parathyroid hormone axis are assessed using clinical chemistries data, renin activity and beta-C-terminal-telopeptide assays, kidney graft RNA-sequencing and serial ultrasonography. We demonstrate that xenografts transplanted from minipigs show only modest growth and do not substantially contribute to recipient RAAS pathway activity. However, parathyroid hormone-independent hypercalcemia and hypophosphatemia are observed, suggesting a need for close monitoring and timely intervention during human testing. Further study of these phenotypes is warranted in designing prospective clinical trials.

Indwelling stents cause obstruction and induce ureteral injury and fibrosis in a porcine model

OBJECTIVES

To investigate global changes in ureters at the transcriptional, translational and functional levels, both while stents are indwelling and after removal and recovery, and to study the effects of targeting pathways that play a potential role.

METHODS

Pig ureters were stented for varying amounts of time (48 h, 72 h, 14 days) and the impact on peristalsis, dilatation and hydronephrosis were assessed. RNAseq, proteomic, histological and smooth muscle (SM) function analyses were performed on ureteric and kidney tissues to assess changes induced by stenting and recovery. Pathway analysis was performed using Ingenuity Pathway Analysis software. To study the impact of possible interventions, the effects of erythropoeitin (EPO) and a Gli1 inhibitor were assessed.

RESULTS

Stenting triggers massive ureteric dilatation, aperistalsis and moderate hydronephrosis within 48 h. Pathways associated with obstruction, fibrosis and kidney injury were upregulated by stenting. Increased expression of GLI1, clusterin-α (a kidney injury marker) and collagen 4A2 (a fibrosis marker) was found in stented vs contralateral unstented ureters. EPO did not improve peristalsis or contraction force but did decrease non-purposeful spasming seen exclusively in stented ureters. Tamsulosin administration increased contractility but not rate of peristalsis in stented ureters.

CONCLUSIONS

Ureters respond to stents similarly to how they respond to an obstruction, that is, with activation of pathways associated with hydronephrosis, fibrosis and kidney injury. This is driven by significant dilatation and associated ureteric SM dysfunction. EPO and tamsulosin induced mild favourable changes in SM physiology, suggesting that targeting specific pathways has potential to address stent-induced complications.

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.

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.

Urinary tract obstruction: Ultrasound-guided intervention

Introduction

Urinary tract obstruction (UTO) is a common clinical problem of which there are many potential causes. The aim of this feature article is to explore the role of ultrasound in diagnosing UTO, during guided interventional procedures and the potential procedural complications.Topic description and discussion: Ultrasound is an integral imaging modality throughout the management pathway of a patient with UTO and is often utilised as a first-line test in diagnosis and treatment. Percutaneous nephrostomy is an interventional technique, usually performed by radiologists or interventional sonographers, as either a short- or long-term management strategy. It can either be used in isolation or to gain access to the renal collecting system prior to more complex interventional or surgical techniques. Ultrasound-guided interventional techniques to relieve UTO can be employed in a number of clinical scenarios each with their own indications, contraindications and complications.

Conclusion

Ultrasound plays a unique role in the planning and active stages of intervention with the provision of dynamic imaging which is crucial for providing safe and effective patient management.

Point‐of‐care renal ultrasound: Are longitudinal views of the kidney alone sufficient to rule out hydronephrosis?

Objective

Point‐of‐care ultrasound for the detection of hydronephrosis is frequently used by emergency physicians. The aim of this study was to assess the accuracy of longitudinal views of the kidney compared with a combination of longitudinal and transverse views of the kidney on emergency physician–performed renal point‐of‐care ultrasound to detect hydronephrosis.

Methods

This was a retrospective case‐control study of patients who received a renal point‐of‐care ultrasound examination performed and interpreted as hydronephrosis in the emergency department (ED). These were then matched with a cohort of kidneys from different patients without hydronephrosis. Longitudinal ultrasound views and transverse ultrasound views were reviewed for the presence of hydronephrosis by ultrasound‐trained emergency physicians. The gold standard of hydronephrosis was an overall interpretation based on the complete ultrasound examination consisting of both transverse and longitudinal views by ultrasound‐trained emergency physicians.

Results

Renal point‐of‐care ultrasound exams from 140 kidneys performed in the ED were enrolled in the study. The sensitivity and specificity of longitudinal ultrasound views compared with a combination of longitudinal and transverse ultrasound views of the kidney as a gold standard were 84.3% (95% confidence interval [CI], 77.2–89.9) and 92.9% (95% CI, 87.3–96.5), the positive predictive value was 92.2% (95% CI, 86.1–96.2), and the negative predictive value was 85.5% (95% CI, 78.9–90.7). The positive and negative likelihood ratios were 11.8 (95% CI, 6.5–21.5) and 0.2 (95% CI, 0.1–0.2), respectively.

Conclusions

Longitudinal views of the kidney on ultrasound showed good sensitivity and specificity to detect the presence of hydronephrosis compared with a combination of longitudinal and transverse ultrasound views of the kidney. However, a combination of longitudinal and transverse ultrasound views may still be warranted in high‐risk patients or in those with inadequate visualization of the upper pole of the kidney.

Reliability assessment of the upper urinary tract dilation grading system based on magnetic resonance urography in patients with neurogenic bladder

Background

To assess the inter-observer and intra-observer reliability of the magnetic resonance urography (MRU)—upper urinary tract dilation (UUTD) grading system.

Methods

A total of 40 patients with a diagnosis of NB were enrolled in this study. The images were assembled in an electronic presentation randomly. The presentations were reviewed and graded by 4 junior and 4 senior urologists. One week later, the images were randomized again and reassessed. The inter-observer reliability was estimated by Kendall’s coefficient of concordance and intra-class correlation coefficient (ICC), and the intra-observer reliability was estimated by weighted Cohen’s kappa.

Results

The inter-observer reliability strength was excellent for all urologists, with the ICC value of 0.939 (0.908–0.963) and Kendall’s W value of 0.967. The highest agreement was shown in Grade 4 at 92.50%, and the lowest in Grade 2 at 82.14%. All disagreements were within one grade of difference. Moreover, the Intra-observer reliability was excellent, with the weighted kappa value ranging from 0.904 to 0.954.

Conclusions

The inter-observer and intra-observer reliability of this novel MRU-UUTD grading system is confirmed, providing adequate evidence for broader clinical application.

A 4-year old presenting with fever and achiness

In children under the age of 5 who have abnormalities in history, physical examination, and laboratory studies indicating multi-system disease, uncovering the correct diagnosis is challenging. Here, we report the course of a 4-year-old girl who presented with a change in behavior, fever, arthralgia, arthritis, and hematuria following three recent hospitalizations for pneumonia and impetigo. Serologic findings were suggestive of a rheumatologic etiology and a renal biopsy was consistent with Membranous Lupus Nephritis Class V which helped secure the diagnosis of pediatric systemic lupus erythematosus. We review the clinical features and diagnostic criteria of early-onset systemic lupus erythematosus and discuss diagnostic considerations and prognosis.

Urinary neutrophil gelatinase-associated lipocalin: a marker of urinary tract infection among febrile children

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a valuable biomarker of urinary tract infection (UTI) in children.

PURPOSE

This study aimed to compare the diagnostic accuracy of urinary NGAL (uNGAL) with those of serum C-reactive protein (CRP) and white blood cell (WBC) count for predicting UTI and acute pyelonephritis (APN) in febrile children.

METHODS

The medical charts of children undergoing uNGAL measurements between November 2017 and August 2019 were retrospectively reviewed. Patients with a suspected or diagnosed UTIs were included. The diagnostic accuracies of uNGAL, serum CRP, and WBC count for detecting UTI and APN were investigated. Independent predictors of UTI and APN were investigated using multivariable logistic regression analyses.

RESULTS

A total of 321 children were enrolled in this study. The uNGAL levels were higher in the UTI group (n=157) than in the non-UTI group (n=164) (P<0.05). Among children with a UTI, uNGAL levels were higher in the APN group (n=70) than, the non-APN group (n=87) (P<0.05). In the multivariate analysis, uNGAL was independently associated with UTI and APN (both P<0.05). Serum CRP and WBC count were not correlated with the presence of UTI and APN. Receiver operating curve analyses showed that the uNGAL level had the highest area under the curve (AUC) for predicting UTI and APN, respectively (AUC, uNGAL vs. CRP vs. WBC count, 0.860 vs. 0.608 vs. 0.669 for UTI; 0.780 vs. 0.680 vs. 0.639 for APN, all P<0.05, respectively). The predictive values and likelihood ratios of uNGAL were superior to those of serum CRP and WBC count for detecting UTI and APN at each cutoff level.

CONCLUSION

UNGAL may be more useful than serum CRP and WBC count for identifying and assessing UTI in febrile children.

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.

Appropriate timing of performing abdominal ultrasonography and termination of follow-up observation for antenatal grade 1 or 2 hydronephrosis

Background

Most cases of antenatal the Society of Fetal Urology (SFU) grade 1or 2 hydronephrosis (HN) improve or resolve spontaneously with conservative treatment. However, there is no consensus on the duration of follow-up for cases of grade 1or 2 HN. The aim of this study was to determine the need for continuous follow-up period and new management of children with antenatal grade 1or 2 HN.

Methods

Subjects underwent ultrasonographic assessment for HN according to the SFU classification. We retrospectively evaluated 112 patients with postnatal grade 1 HN and 69 with grade 2 HN using abdominal ultrasonography between January 2010 and December 2017. We examined the change in HN grade on repeat ultrasonography. Kaplan–Meier method was used to show the effect of HN grade on the rate of HN changes.

Results

The mean follow-up duration was 44.9 ± 36.4 months (range 12–274). Initial SFU grade 1 HN disappeared in 47.0% of cases at 12 months, 66.4% at 24 months and 73.2% at 48 months. Initial SFU grade 2 HN showed improvement in grade in 74.7% of cases at 12 months, 88.3% at 24 months and 89.5% at 48 months. However, 14.6% of SFU grade 1 and 2.8% of SFU grade 2 cases increased in grade and of the 17 cases, 16 cases worsened within the first 6 months. No cases with increased grade required pyeloplasty. Initial disappearance and later reappearance of HN occurred in 40.5% of SFU grade 1 and 2 cases. The mean duration of later reappearance of HN was 39.1 ± 36.2 months (range 12–137). No cases showed reappearance of HN after more than 1 year.

Conclusions

Ultrasonography within the first 6 months was necessary for management of children with antenatal grade 1or 2 HN, because some patients showed worsening. After that, it is considered safe to spread the follow-up interval for stable cases. Most cases of grade 1or 2 HN resolved spontaneously, however a few cases reappeared within 1 year. Therefore, ultrasonography after 1 year was necessary in children with HN that spontaneously disappeared. The appropriate time to end the follow-up was considered to have been after 1 year or more has passed since the disappearance was confirmed.

Using Deep Learning Algorithms to Grade Hydronephrosis Severity: Toward a Clinical Adjunct

Grading hydronephrosis severity relies on subjective interpretation of renal ultrasound images. Deep learning is a data-driven algorithmic approach to classifying data, including images, presenting a promising option for grading hydronephrosis. The current study explored the potential of deep convolutional neural networks (CNN), a type of deep learning algorithm, to grade hydronephrosis ultrasound images according to the 5-point Society for Fetal Urology (SFU) classification system, and discusses its potential applications in developing decision and teaching aids for clinical practice. We developed a five-layer CNN to grade 2,420 sagittal hydronephrosis ultrasound images [191 SFU 0 (8%), 407 SFU I (17%), 666 SFU II (28%), 833 SFU III (34%), and 323 SFU IV (13%)], from 673 patients ranging from 0 to 116.29 months old (M age = 16.53, SD = 17.80). Five-way (all grades) and two-way classification problems [i.e., II vs. III, and low (0-II) vs. high (III-IV)] were explored. The CNN classified 94% (95% CI, 93-95%) of the images correctly or within one grade of the provided label in the five-way classification problem. Fifty-one percent of these images (95% CI, 49-53%) were correctly predicted, with an average weighted F1 score of 0.49 (95% CI, 0.47-0.51). The CNN achieved an average accuracy of 78% (95% CI, 75-82%) with an average weighted F1 of 0.78 (95% CI, 0.74-0.82) when classifying low vs. high grades, and an average accuracy of 71% (95% CI, 68-74%) with an average weighted F1 score of 0.71 (95% CI, 0.68-0.75) when discriminating between grades II vs. III. Our model performs well above chance level, and classifies almost all images either correctly or within one grade of the provided label. We have demonstrated the applicability of a CNN approach to hydronephrosis ultrasound image classification. Further investigation into a deep learning-based clinical adjunct for hydronephrosis is warranted.

Symptomatology and Clinic of Hydronephrosis Associated With Uretero Pelvic Junction Anomalies

The most common cause of hydronephrosis in the pediatric age group is ureteropelvic junction-type hydronephrosis (UPJHN). Since the advent of widespread maternal ultrasound screening, clinical presentation of hydronephrosis associated with UPJ anomalies has changed dramatically. Today most cases are diagnosed in the prenatal period, and neonates present without signs or symptoms. For those who are not detected at birth, UPJHN eventually presents throughout childhood and even adulthood with various symptoms. Clinical picture of UPJHN highly depends on the presence and severity of obstruction, and whether it affects single or both kidneys. Abdominal or flank pain, abdominal mass, hematuria, kidney stones, urinary tract infections (UTI), and gastrointestinal discomfort are the main symptoms of UPJHN in childhood. Other less common findings in such patients are growth retardation, anemia, and hypertension. UTI is a relatively rare condition in UPJHN cases, but it may occur as pyelonephritis. Vesicoureteric reflux should be kept in mind as a concomitant pathology in pediatric UPJHN that develop febrile UTI. Although many UPJHN cases are known to improve over time, close clinical observation is critical in order to avoid irreversible kidney damage. The most appropriate approach is to follow-up the patients considering the presence of symptoms, the severity of hydronephrosis and the decrease in kidney function and, if necessary, to decide on early surgical intervention.

Urinary Ultrasound and Other Imaging for Ureteropelvic Junction Type Hydronephrosis (UPJHN)

Ultrasound is the main imaging study used to diagnose ureteropelvic junction (UPJ) obstruction. On ultrasound, abnormal dilatation of the pelvicalyceal system of varying degrees is seen, whereas the ureter is normal in caliber. A properly performed study provides essential information regarding laterality, renal size, thickness, and architecture of the renal cortex and degree of dilatation of the pelvicalyceal system. Doppler ultrasound may identify a crossing vessel, when present. This imaging method also has been used differentiating obstructive from non-obstructive hydronephrosis by renal arterial resistive index measurements. Abdominal radiographs may show soft tissue fullness, bulging of the flank, and displacement of bowel loops from the affected side. The voiding/micturating cystourethrogram helps exclude other causes of upper tract dilatation, including vesicoureteral reflux, urethral valves, and ureteroceles. Computerized Tomography angiography with multiplanar reformation and three-dimensional images may be used to depict suspected crossing vessels as a cause of UPJ obstruction in older children and adults. Magnetic Resonance Urography has progressed significantly in recent years due to the development of both hardware and software that are used to generate high-resolution images. This imaging technique currently allows for the detailed assessment of urinary tract anatomy, while also providing information regarding renal function, including differential renal function, and the presence or absence of obstructive uropathy.

Grading of Hydronephrosis: An Ongoing Challenge

The crucial point for prompt diagnostics, ideal therapeutic approach, and follow-up of hydronephrosis associated with UPJ anomalies in children is the severity of hydronephrosis. Such many hydronephrosis grading systems as AP diameter, SFU, radiology, UTD, and Onen have been developed to evaluate hydronephrosis severity in infants. Unfortunately, it is still an ongoing challenge and there is no consensus between different disciplines. AP diameter is a very dynamic parameter and is affected by many factors (hydration, bladder filling, position, respiration). More importantly, its measurement is very variable and misleading due to different renal pelvic configurations. The radiology grading system has the same grades 1, 2, and 3 as the SFU grading system with addition of the AP diameter for the first 3 grades. This grading system divides parenchymal loss into two different grades. Grade 4 represents mild parenchymal loss while grade 5 suggests severe parenchymal loss. However, it is operator dependent, is not decisive, and does not differentiate grades 4 and 5 clearly. All grades of SFU are very variable between operators and clinicians. UTD classification aims to put all significant abnormal urinary findings together including the kidney, ureter, and bladder and thus determines the risk level for infants with any urinary disease. Different renal deterioration risks occur depending on the mechanism of hydronephrosis. Therefore, SFU and UTD classification may result in significant confusion and misleading in determining the severity of hydronephrosis. SFU-4 and UTD-P3 represent a considerable range of severity of hydronephrosis. Both represent minimal thinning of the medullary parenchyma and severe thinning of the cortical parenchyma (cyst-like hydronephrotic kidneys) at the same grade. The wide definition of SFU-4 and UTD-P3 fails to indicate accurately the severity of hydronephrosis and thus significantly misleads from a prompt treatment. They do not suggest who need surgical treatment and who can safely be followed non-operatively. The anatomy and physiology of the 4 suborgans of the kidney (renal pelvis, calices, medulla, and cortex) are completely different from each other. Therefore, each part of the kidney affect and behave differently as a response to UPJ-type hydronephrosis (UPJHN) depending on the severity of hydronephrosis. The upgraded Onen hydronephrosis grading system has been developed based on this basic evidence both for prenatal and post-natal periods. The Onen grading system determines specific detailed findings of significant renal damage, which clearly show and suggest who can safely be followed conservatively from who will need surgical intervention for UPJHN. Neither AP diameter nor radiology, SFU, or UTD classification is the gold standard in determining the severity of hydronephrosis. All these grading systems are based on subjective parameters and are affected by many factors. They do not determine the exact severity of UPJHN and thus cause permanent renal damage due to a delay in surgical decision in some infants while they may cause an unnecessary surgery in others. The Onen grading system has resolved all disadvantages of other grading systems and promises a safer follow-up and a prompt treatment for UPJHN. It is an accurate and easily reproducible grading that has high sensitivity and specificity.

Inter-observer variability amongst surgeons and radiologists in assessment of Guy's Stone Score and S.T.O.N.E. nephrolithometry score: A prospective evaluation

Objective

(a) To assess the inter-observer variability amongst surgeons performing percutaneous nephrolithotomy (PCNL) and radiologists for the Guy’s Stone Score (GSS) and S.T.O.N.E. (stone size [S], tract length [T], obstruction [O], number of involved calyces [N], and essence or stone density [E]) nephrolithometry score; (b) To determine which scoring system of the two is better for predicting the stone-free rate (SFR) after PCNL.

Patients, subjects and methods

Patients undergoing PCNL between February 2016 and September 2016 were prospectively enrolled. Preoperative computed tomography was done in all patients. The GSS and S.T.O.N.E. nephrolithometry score were independently calculated by eight surgeons and four radiologists. The patients were operated on by one of the surgeons (all were consultants). The Fleiss’ κ coefficient was used to assess agreement independently between the surgeons and radiologists. Receiver operating characteristic (ROC) curves were constructed for predicting the SFR using the average of the scores of the surgeons and radiologists separately.

Results

A total of 157 patients underwent PCNL. The SFR was 71.3% (112/157 patients). The Fleiss’ κ scores ranged from 0.51 to 0.88 (overall 0.79) for the S.T.O.N.E. score and 0.53–0.91 for the GSS, suggesting moderate to very good agreement. The ROC curve for the S.T.O.N.E. nephrolithometry scores of surgeons (area under the curve [AUC] = 0.806) as well as the radiologists (AUC = 0.810) had a higher predictive value for the SFR than the GSS of the surgeons (AUC = 0.738) and the radiologists (AUC = 0.747).

Conclusion

There is overall good agreement between surgeons and radiologists for both the GSS and S.T.O.N.E. nephrolithometry score. The S.T.O.N.E. score had a higher predictive value for the SFR than the GSS.

Abbreviations

AUC: area under the curve; GSS: Guy’s Stone Score; KUB: kidneys, ureters and bladder; NCCT: non-contrast CT; PCNL: Percutaneous nephrolithotomy; ROC: receiver operating characteristic; SFR: stone-free rate; S.T.O.N.E.: stone size [S], tract length [T], obstruction [O], number of involved calyces [N], and essence or stone density [E]

Retrospective analysis of computed tomography-guided percutaneous nephrostomies in cancer patients

Objective

To establish an overview of computed tomography (CT)-guided percutaneous nephrostomy performed at a referral center for cancer, addressing the characteristics of patients submitted to this intervention, as well as the indications for it, the technical specificities of it, and its main complications.

Materials and Methods

This was a retrospective study involving a review of the electronic medical records and images of patients submitted to CT-guided percutaneous nephrostomy at a referral center for cancer between 2014 and 2016.

Results

A total of 201 procedures were evaluated. In most cases, the obstruction was caused by a malignant neoplasm. Complications occurred in 9.5% of the cases, and an additional intervention was required (typically for catheter repositioning) in 36.6%. Post-procedure complications were not found to be significantly associated with the type of previous cancer treatment, the technique used, the caliber of the drain used in the procedure, or the degree of dilatation of the collection system prior to the procedure.

Conclusion

In cancer patients, CT-guided percutaneous nephrostomy is an effective treatment, with success rates and complication rates similar to those reported in the general population.

Natural course of isolated mild congenital hydronephrosis: A 2-year prospective study at a single center in Japan

OBJECTIVES

To determine a follow-up plan for mild congenital hydronephrosis in Japanese individuals.

METHODS

Neonates at Kansai Medical University Hospital (Hirakata, Osaka, Japan) who were diagnosed with mild congenital hydronephrosis - defined as a Society for Fetal Urology grade 1 or 2 - at 1-month old by abdominal ultrasonography between 2014 and 2016 were enrolled. These patients were encouraged to undergo repeated abdominal ultrasonography for 2 years every 3 months to investigate the course of congenital hydronephrosis.

RESULTS

Among 1009 neonates, congenital hydronephrosis was detected in 118 affected renal units of 100 (9.9%) patients. According to the definition of the Society for Fetal Urology, 118 affected renal units were graded as grade 1 in 87 (74%), grade 2 in 30 (25%), grade 3 in one (1%) and grade 4 in 0 units. Among them, 117 affected renal units of mild congenital hydronephrosis comprising grades 1 and 2 were subjected to ultrasonographic evaluation to monitor the natural course. The rates of resolution at 7, 10, 13, 16, 19, 22 and 25 months after birth in Society for Fetal Urology grades 1 and 2 cases were 60% and 8%, 77% and 19%, 90% and 32%, 92% and 40%, 95% and 52%, 96% and 56%, and 99% and 60%, respectively.

CONCLUSIONS

Grade 1 congenital hydronephrosis does not need to be followed up, because it mostly shows spontaneous resolution by 2 years of follow up without any complications. However, ultrasonographic examinations at 1-year intervals for grade 2 congenital hydronephrosis are recommended to determine the subsequent follow-up plan of patients.

Rater reliability of postnatal urinary tract dilation consensus classification

BACKGROUND

A multidisciplinary urinary tract dilation (UTD) classification system was published in 2014 to standardize definitions and renal/bladder ultrasound image interpretation.

OBJECTIVE

To evaluate intra- and inter-rater reliability of this system on postnatal RBUS.

MATERIALS AND METHODS

Renal/bladder US of 60 infants (<12 months) with urinary tract dilation were anonymized, retrospectively reviewed and scored twice using the UTD classification system by a pediatric urologist and four pediatric radiologists. Exams included supine and prone images of each kidney. Raters recorded the anterior posterior renal pelvis diameter in each position; and when present calyceal dilation (central and peripheral), ureteral dilation, parenchymal and bladder abnormalities. A UTD score was given to each kidney based on these components.

RESULTS

Intraclass correlation (ICC) of anterior posterior renal pelvis diameter measures was 0.99 (P<0.001). Intra-rater reliability for the anterior posterior renal pelvis diameter of each kidney was high, with ICC >0.95 (P<0.001). Inter-rater kappa values for UTD scores of both kidneys ranged from 0.60 to 0.77 (P <0.001). Intra-rater kappa values for UTD scores of both kidneys ranged from 0.74 to 0.92 (P <0.001). Of the six categories comprising the UTD score, discrepancy between raters was highest for interpretation of central and peripheral calyceal dilation.

CONCLUSION

Present inter- and intra-rater reliability findings were similar to those previously reported for grading systems for urinary tract dilation. Across these studies, kappa values are generally lower than the 0.8 cut-off advocated for medical measures. Here, calyceal dilation commonly determined the kidney UTD score and was also the source of greatest discrepancy between raters. Improving consistency of calyceal dilation interpretation may improve UTD consensus score reliability.

How may Doppler indices help in the differentiation of obstructive from nonobstructive hydronephrosis?

Background:

We assess the potency of different Doppler indices in the differentiation of obstructive and nonobstructive hydronephrosis.

Materials and Methods:

In this study, infants and children who were referred for the evaluation of unilateral hydronephrosis were enrolled. Ultrasonography for the assessment of the degree of hydronephrosis and a voiding cystourethrogram for the exclusion of vesicoureteral reflux was performed. Then, Doppler ultrasonography was done for both kidneys of each patient using four classic Doppler indices as well as the difference (delta) of each index between to kidneys. Diuretic renography with 99 mTc-ethylene dicysteine (99 mTc-EC) was performed for each patient.

Results:

Thirty-nine patients met the inclusion criteria. After diuretic renography, 29 (74.35%) patients had shown a nonobstructive pattern, and ten (25.65%) patients had a partial (intermediate) or complete obstruction. Using receiver operating characteristic (ROC) curve, none of the classic indices of Doppler duplex (i.e., resistive index [RI], resistance index, end diastolic velocity, and peak systolic velocity) had the ability to make a difference between obstructive and nonobstructive hydronephrosis. However, by calculating the difference (delta) of these indices between two kidneys of each patient, delta RI could differentiate the nonobstructive condition, significantly (P = 0.006). A cutoff value of 0.055 has 60% sensitivity and 82.8% specificity. The area under the ROC curve for delta RI is 0.795 (standard error: 0.086, 95% confidence interval [CI]: 0.626, 0.964). Furthermore, RI ratio between two kidneys of each patient could differentiate the nonobstructive condition, significantly (P = 0.012). A cutoff point of 1.075 has 70% sensitivity and 82.8% specificity. The area under the ROC curve for RI ratio was 0.769 (standard error: 0.104, 95% CI: 0.565, 0.973).

Conclusion:

This study shows that RI ratio and delta RI with a high specificity could differentiate nonobstructive hydronephrosis and therefore it is a promising way to use especially in the follow-up of children with hydronephrosis.

Hydronephrosis After Pyeloplasty: "Will It Go Away?"

OBJECTIVE

To identify attributes of pediatric patients with hydronephrosis due to ureteropelvic junction obstruction and of their surgical encounters which are predictive of resolution of dilatation in order to provide more effective counseling about expected outcomes. This study was inspired by the suggestion in recent literature that greater than 20% improvement in anteroposterior diameter (APD) of the renal pelvis after pyeloplasty is indicative of resolution of obstruction. The remaining dilatation, however, is often distressing to caregivers, and there are no data to guide clinicians in counseling about its likelihood to resolve.

METHODS

We retrospectively reviewed children who underwent surgery at our institution for ureteropelvic junction obstruction between 1/01/2010 and 6/30/2017. APD of the pre- (preAPD) and postoperative (postAPD) renal pelves were documented. In children with more than 1 postoperative ultrasound, lastAPD was the measurement on their most recent study. Appropriate statistical tests examined the effects of clinical and surgical variables on hydronephrosis resolution.

RESULTS

PostAPD and lastAPD were obtained at medians of 3 months and 1.9 years after surgery, and were 0 cm in 12 of 105 (11.5%) and 9 of 65 (13.8%) patients, respectively. None of the variables analyzed significantly impacted complete resolution at either time point. Of those that did not resolve, 80.6% (75/93) showed greater than 20% improvement in APD; however, 3 of these children required reoperation due to secondary obstruction. In our study, no one with APD reduction greater than 43% required reintervention.

CONCLUSION

Complete resolution of hydronephrosis is uncommon and unpredictable. All caregivers should be counseled to expect dilatation to persist after obstruction is corrected.

Ultrasound screening for pyelectasis in pregnant women. Clinical necessity or "art for art's sake"?

Renal pelvicalyceal dilatation is caused by urine retention in the upper urinary tract. It is referred to as pyelectasis in medical literature. This term does not indicate the cause that leads to the dilatation of and urine retention in the renal pelvicalyceal system. Mild pelvicalyceal dilatation during pregnancy is usually considered to be physiological in nature – it can occur in up to 90% of pregnant women. Retention is more common in the right kidney, in primigravidae, in the second half of pregnancy and in multiple pregnancies. Pyelectasis during pregnancy rarely causes clinical symptoms and often does not require treatment. Nevertheless, urine retention in the renal pelvicalyceal system is conducive to the development of asymptomatic bacteriuria and may be a risk factor for recurrent urinary tract infections, pyelonephritis and acute kidney failure; it may also cause renal colic. In consequence, this condition can lead to intrauterine infection and premature labor in the pregnant woman and to prematurity, anemia, congenital pneumonia or sepsis in the child. In a study conducted at the 3^rd Department of Gynecology of the Medical University of Lublin it was concluded that unilateral pyelectasis of more than 20 cm³ is associated with a significant increase in the risk of asymptomatic bacteriuria. This volume corresponds to grade 3 and/or 4 pelvicalyceal dilatation according to the Society for Fetal Urology/European Federation of Societies for Ultrasound in Medicine and Biology classification. The pyelectasis volume measuring method using three-dimensional ultrasound scanning included in the criteria for the assessment of asymptomatic bacteriuria was assessed as sensitive and specific. The ultrasound-based evaluation of the kidneys for the presence of pyelectasis and its grade in pregnant women has some clinical implications. It allows for identifying cases with an increased risk of asymptomatic bacteriuria, which requires treatment in pregnant women. Screening during pregnancy for pyelectasis seems to be important in preventing asymptomatic bacteriuria from progressing to symptomatic urinary tract infection.

Is the renal pyramidal thickness a good predictor for pyeloplasty in postnatal hydronephrosis?

OBJECTIVES

We evaluated the feasibility and value of renal pyramidal thickness (PT) as a predictor of pyeloplasty in high-grade postnatal hydronephrosis.

PATIENTS AND METHODS

We retrospectively reviewed the charts of patients who presented with postnatal hydronephrosis from 2008 to 2013. Included cases had grade 3 or 4 hydronephrosis. We included only units diagnosed as ureteropelvic junction obstruction. Gender, laterality, hydronephrosis side, renogram data, and follow-up data were recorded. Two investigators reviewed all patients' ultrasounds images. We measured PT and pelvic anteroposterior diameter (APD) in the last ultrasound before surgery. For those managed conservatively, measurements were obtained from the ultrasound with worst hydronephrosis. PT was measured in supine position in the middle third of the sagittal plane (Figure). We assessed the reliability of PT measurement using the intraclass correlation coefficient (ICC). Univariate and multivariate analyses were used to correlate the collected parameters to pyeloplasty incidence. Receiver operating characteristic curve was used to evaluate the cutoff value of PT that predicts pyeloplasty.

RESULTS

The total included cases were 155 patients (165 units). One hundred and fourteen units had grade 3 hydronephrosis and 51 units had grade 4 hydronephrosis. Fifty-two cases (55 units) underwent pyeloplasty. The median follow-up period was 37.6 months. PT measurement was reliable (ICC = 0.94). Univariate analysis revealed that SFU grading, APD, PT, T1/2, and MAG-3 curves were associated with surgery. Multivariate analysis showed that PT was a single independent predictor for pyeloplasty. PT ≤ 3 mm had 98.1% sensitivity and 89.7% specificity in predicting pyeloplasty.

DISCUSSION

PT is the first portion of renal parenchyma that is affected in high-grade hydronephrosis. Moreover, it changes little over the first 9 years of life. PT measurement in hydronephrosis was not previously evaluated. We found that PT was easily measured in most kidneys with high negative predictive value. The PT value as an indicator for pyeloplasty should undergo extensive assessment by other institutions with different protocols.

CONCLUSION

Being a slowly growing part of the parenchyma, PT can be a good measurable parameter to predict pyeloplasty. Measurement of PT in hydronephrosis is reliable. PT ≤ 3 mm can predict pyeloplasty with 98.1% sensitivity and 89.7% specificity.

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.

Urinary YKL-40 as a Candidate Biomarker for Febrile Urinary Tract Infection in Young Children

Background

Given that YKL-40 is a known marker of inflammation, we sought to determine its association with urinary tract infection (UTI) in febrile children.

Methods

In total, 44 children aged 0 to 24 months with febrile UTI and 35 age- and sex-matched controls with fever from other causes were enrolled in the study. ELISA was performed to determine the level of YKL-40 in urine collected from each child.

Results

The ratio of urinary YKL-40 to creatinine (Cr) was higher in the children with a UTI than in the controls (P<0.001). The area under the ROC curve for detecting UTI was 0.88 for the urinary YKL-40/Cr ratio, 0.86 for pyuria, and 0.71 for positive nitrite on urinalysis. We applied a cut-off value of 125.23 pg/mg to urinary YKL-40/Cr for detecting UTI. Eight of nine children in the control group with pyuria had urinary YKL-40/Cr levels lower than 125.23 pg/mg, and the one child in the UTI group without pyuria or positive nitrite had a urinary YKL-40/Cr level greater than 125.23 pg/mg.

Conclusions

Determining the levels of urinary YKL-40/Cr may help identify true cases of UTI in febrile young children, especially when they have pyuria but not nitrite, or have neither pyuria nor nitrite in the urine.

Simple visual review of pre- to post-operative renal ultrasound images predicts pyeloplasty success equally as well as geometric measurements: A blinded comparison with a gold standard

BACKGROUND

MAG3 diuretic renal scan remains the gold standard for determination of improvement in renal drainage following pyeloplasty for ureteropelvic junction obstruction. We hypothesized that (i) a change in geometric measurements between pre-operative and post-operative renal ultrasound (RUS) images and (ii) blinded simple visual review of images both would predict pyeloplasty success.

OBJECTIVE

To determine if simple visual review and/or novel geometric measurement of renal ultrasounds can detect pyeloplasty failure.

STUDY DESIGN

This study was a retrospective, blinded comparison with a gold standard. Included were children aged ≤18 years undergoing pyeloplasty at our institution from 2009 to 2015. For each kidney, representative pre-operative and post-operative RUS images were chosen. Our standard for pyeloplasty success was improved drainage curve on MAG3 and lack of additional surgery. Measurements for collecting system circularity, roundness, and renal parenchymal to collecting system area ratio (RPCSR) were obtained by three raters (Figure), who were blinded to the outcome of the pyeloplasty. Changes in geometric measurements were analyzed as a diagnostic test for MAG3-defined pyeloplasty success using ROC curve analysis. In addition, six reviewers blinded to pyeloplasty success reviewed pre-operative and post-operative images visually for improved hydronephrosis and categorized pyeloplasty as success or failure based on simple visual review of RUS.

RESULTS

Fifty-three repaired renal units were identified (50 children). There were five pyeloplasty failures, four of which underwent revision or nephrectomy. While all geometric measurements could discriminate pyeloplasty failure and success, the geometric measurements that discriminated best between pyeloplasty failure and success were change in collecting system roundness and change in RPCSR. Consensus opinion among six blinded reviewers using simple visual review had a sensitivity of 94% and PPV of 100% with respect to identifying pyeloplasty success (AUC 0.97 (95% CI 0.93-1.0)). This was not significantly different from AUC for change in roundness (p = 0.09) or change in RPCSR (p = 0.1).

DISCUSSION

Change in collecting system roundness and change in RPCSR were the most accurate geometric measurements in predicting pyeloplasty success. Simple visual review of ultrasound images for pyeloplasty success performed as well or better than geometric measurements. However, geometric measurements remain useful as a research tool or to communicate findings between clinicians.

CONCLUSIONS

Complex geometric measurements of hydronephrosis or post-operative MAG3 scans are not needed if hydronephrosis is visually significantly improved, as simple visual review is highly sensitive for detecting pyeloplasty failure.

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.

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.

Prognostic Value of Ultrasound Grading Systems in Prenatally Diagnosed Unilateral Urinary Tract Dilatation

PURPOSE

We compared the prognostic value of anteroposterior intrasinus diameter of the renal pelvis, urinary tract dilatation and the Society for Fetal Urology grading system in children with prenatally diagnosed unilateral urinary tract dilatation.

MATERIALS AND METHODS

All newborns with prenatally diagnosed unilateral urinary tract dilatation, normal bladder and anteroposterior intrasinus diameter 10 mm or greater on the first postnatal ultrasonography were prospectively enrolled from January 2011 to February 2015. Indications for surgery were recurrent febrile urinary tract infections and/or decrease of relative renal function more than 10% on serial isotope studies and/or increasing anteroposterior intrasinus diameter greater than 20% on serial ultrasounds. Sensitivity, specificity and ROC curves were calculated to evaluate the accuracy of anteroposterior intrasinus diameter, urinary tract dilatation and Society for Fetal Urology grading system in determining which children would need surgery within 24 months.

RESULTS

A total of 57 males and 13 females were included. Of the patients 33 required surgery at a median age of 5 months (IQR 3.8 to 6.4). Urinary tract dilatation remained stable in 14 cases and decreased in 23 with a median followup of 42 months (IQR 25 to 67). Anteroposterior intrasinus diameter, urinary tract dilatation and Society for Fetal Urology scores were all correlated with the need for surgery. Anteroposterior intrasinus diameter with a threshold of 20 mm had the best prognostic value, with a sensitivity of 81.8% and a specificity of 91.7%.

CONCLUSIONS

Our study confirms that the prognostic value was comparable between anteroposterior intrasinus diameter of the renal pelvis, urinary tract dilatation and Society for Fetal Urology grading system in newborns with prenatally diagnosed unilateral urinary tract dilatation. Anteroposterior intrasinus diameter and abnormal parenchymal thickness are the most important ultrasound criteria to identify children at risk for requiring surgery.

Renal Segmentation From 3D Ultrasound via Fuzzy Appearance Models and Patient-Specific Alpha Shapes

Ultrasound (US) imaging is the primary imaging modality for pediatric hydronephrosis, which manifests as the dilation of the renal collecting system (CS). In this paper, we present a new framework for the segmentation of renal structures, kidney and CS, from 3DUS scans. First, the kidney is segmented using an active shape model-based approach, tailored to deal with the challenges raised by US images. A weighted statistical shape model allows to compensate the image variation with the propagation direction of the US wavefront. The model is completed with a new fuzzy appearance model and a multi-scale omnidirectional Gabor-based appearance descriptor. Next, the CS is segmented using an active contour formulation, which combines contour- and intensity-based terms. The new positive alpha detector presented here allows to control the propagation process by means of a patient-specific stopping function created from the bands of adipose tissue within the kidney. The performance of the new segmentation approach was evaluated on a dataset of 39 cases, showing an average Dice's coefficient of 0.86±0.05 for the kidney, and 0.74 ± 0.10 for the CS segmentation, respectively. These promising results demonstrate the potential utility of this framework for the US-based assessment of the severity of pediatric hydronephrosis.

Urinary Imaging Findings in Young Infants With Bacteremic Urinary Tract Infection

OBJECTIVES

To describe renal ultrasound (RUS) and voiding cystourethrogram (VCUG) findings and determine predictors of abnormal imaging in young infants with bacteremic urinary tract infection (UTI).

METHODS

We used retrospective data from a multicenter sample of infants younger than 3 months with bacteremic UTI, defined as the same pathogenic organism in blood and urine. Infants were excluded if they had any major comorbidities, known urologic abnormalities at time of presentation, required intensive unit care, or had no imaging performed. Imaging results as stated in the radiology reports were categorized by a pediatric urologist.

RESULTS

Of the 276 infants, 19 were excluded. Of the remaining 257 infants, 254 underwent a RUS and 224 underwent a VCUG. Fifty-five percent had ≥1 RUS abnormalities. Thirty-four percent had ≥1 VCUG abnormalities, including vesicoureteral reflux (VUR, 27%), duplication (1.3%), and infravesicular abnormality (0.9%). Age <1 month, male sex, and non-Escherichia coli organism predicted an abnormal RUS, but only non-E coli organism predicted an abnormal VCUG. Seventeen of 96 infants (17.7%) with a normal RUS had an abnormal VCUG: 15 with VUR (Grade I-III = 13, Grade IV = 2), 2 with elevated postvoid residual, and 1 with infravesical abnormality.

CONCLUSIONS

Although RUS and VCUG abnormalities were common in this cohort, the frequency and severity were similar to previous studies of infants with UTIs in general. Our findings do not support special consideration of bacteremia in imaging decisions for otherwise well-appearing young infants with UTI.

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.

Increasing the Reliability of the Grading System for Voiding Cystourethrograms Using Ultrasonography: An Inter-Rater Comparison

BACKGROUND

To assess the effectiveness of the current vesicoureteral reflux (VUR) grading system according to the international classification of VUR (ICVUR) and to evaluate whether VUR grading accuracy could be improved by renal ultrasonography (RU) according to the Society for Fetal Urology (SFU) grading system.

OBJECTIVES

Therefore, this study assessed the accuracy of the current VCUG staging system by assessing inter-rater reliability among pediatric radiologists and urologists; it also evaluated whether accuracy is increased by RU without consensus (with respect to VCUG grading).

METHODS

Four pediatric urologists and four pediatric radiologists independently graded 120 voiding cystourethrograms (VCUGs). Middle VUR grades were divided into the following three groups: VUR consensus grade III (group 1), VUR consensus grade IV (group 3), and VUR non-consensus grades III and IV (group 2). All groups were compared with respect to hydronephrosis grade using RU.

RESULTS

The intraclass correlation coefficient (ICC) values ranging from 0.86 to 0.89 reflected good reliability. The lowest agreement was associated with middle grades (III and IV). A marked difference in sensitivity was observed between groups 1 and 3 (35% and 95%, respectively, P < 0.05), indexed by SFU hydronephrosis grade, suggesting that VCUG cases in group 2 (n = 16 at SFU 0 or 1) could be accepted as grade III, and SFU scores of 2, 3, or 4 could be considered grade IV.

CONCLUSIONS

Inter-rater accuracy could be improved at middle grades using renal ultrasonography (USG), which could promote communication between different specialists.

Ultrasonography of hydronephrosis in the newborn: a practical review

Widespread use of fetal ultrasonography is accompanied by more frequent detection of antenatal hydronephrosis. Therefore, sonographic evaluation of neonates with a history of antenatal hydronephrosis is becoming more widespread. As an initial postnatal non-invasive imaging modality, ultrasonography is used to screen for persistence of hydronephrosis, determine the level and severity of obstruction, and contribute to appropriate diagnosis and treatment. This review aims to provide a practical overview of the sonographic evaluation of neonatal hydronephrosis and to describe the sonographic findings of conditions associated with hydronephrosis in the newborn.

Evaluation of Urinary Tract Dilation Classification System for Grading Postnatal Hydronephrosis

PURPOSE

We assessed the reliability and validity of the Urinary Tract Dilation classification system as a new grading system for postnatal hydronephrosis.

MATERIALS AND METHODS

We retrospectively reviewed charts of patients who presented with hydronephrosis from 2008 to 2013. We included patients diagnosed prenatally and those with hydronephrosis discovered incidentally during the first year of life. We excluded cases involving urinary tract infection, neurogenic bladder and chromosomal anomalies, those associated with extraurinary congenital malformations and those with followup of less than 24 months without resolution. Hydronephrosis was graded postnatally using the Society for Fetal Urology system, and then the management protocol was chosen. All units were regraded using the Urinary Tract Dilation classification system and compared to the Society for Fetal Urology system to assess reliability. Univariate and multivariate analyses were performed to assess the validity of the Urinary Tract Dilation classification system in predicting hydronephrosis resolution and surgical intervention.

RESULTS

A total of 490 patients (730 renal units) were eligible to participate. The Urinary Tract Dilation classification system was reliable in the assessment of hydronephrosis (parallel forms 0.92). Hydronephrosis resolved in 357 units (49%), and 86 units (12%) were managed by surgical intervention. The remainder of renal units demonstrated stable or improved hydronephrosis. Multivariate analysis revealed that the likelihood of surgical intervention was predicted independently by Urinary Tract Dilation classification system risk group, while Society for Fetal Urology grades were predictive of likelihood of resolution.

CONCLUSIONS

The Urinary Tract Dilation classification system is reliable for evaluation of postnatal hydronephrosis and is valid in predicting surgical intervention.

Teaching of the Society for Fetal Urology grading system for pediatric hydronephrosis is improved by e-Learning using Computer Enhanced Visual Learning (CEVL): A multi-institutional trial

INTRODUCTION

It is unclear how clinicians learn to grade pediatric hydronephrosis (HN) and how effective their training has been. We sought to: 1. Assess how clinicians learn to grade HN and their confidence in their training and abilities and 2. To assess Computer Enhanced Visual Learning (CEVL) e-Learning to learn the Society for Fetal Urology (SFU) grading system for pediatric HN.

METHODS AND MATERIALS

A multi-institutional online survey was distributed to pediatric urologists, nephrologists, and radiologists. Respondents used a 6-point Likert scale (0 = not confident to 5 = very confident) to assess their confidence in knowledge of the criteria, indications, and ability to grade HN, and how they learned to grade. Participants assigned SFU grades to 15 neonatal ultrasounds (US). A CEVL module on the SFU grading system was accessed and a post-CEVL survey completed. Changes in confidence and accuracy of grading were compared before and after CEVL e-Learning.

RESULTS

The most common method of learning was "casually during training" (44.5%). Significant increases in confidence in knowledge of criteria, indications, and ability to grade, as well as the accuracy of grading were seen following CEVL e-Learning (Figure A and B).

DISCUSSION

Although the SFU grading system is considered the predominant grading system for HN, its application in clinical practice has been inconsistent. While this may be due to the grading system itself, it is possible that deficient training and confidence are the root causes. Our data supports this by demonstrating that most clinicians receive only casual training and accordingly, report low confidence in their knowledge and ability to grade HN. Therefore, we conclude that there exists a strong need to improve the teaching of the SFU grading system. e-Learning has been shown to be effective in teaching difficult topics and skills. We demonstrate that e-Learning with CEVL is effective in increasing both the confidence and accuracy of SFU grading of pediatric HN. Limitations of our study include a small sample size, low response rate, and discrepant participation. Furthermore, we did not assess the extent to which the CEVL module was used or include a control group learning through traditional means. Therefore, we were unable to evaluate the efficiency of learning or be certain that the improvements seen were derived exclusively from CEVL.

CONCLUSION

Current training in SFU grading of HN is mostly unstructured and inaccurate grading is common. Learners who use CEVL show improvements in their confidence and ability to SFU grade HN.

Multidisciplinary consensus on the classification of prenatal and postnatal urinary tract dilation (UTD classification system)

OBJECTIVE

Urinary tract (UT) dilation is sonographically identified in 1-2% of fetuses and reflects a spectrum of possible uropathies. There is significant variability in the clinical management of individuals with prenatal UT dilation that stems from a paucity of evidence-based information correlating the severity of prenatal UT dilation to postnatal urological pathologies. The lack of correlation between prenatal and postnatal US findings and final urologic diagnosis has been problematic, in large measure because of a lack of consensus and uniformity in defining and classifying UT dilation. Consequently, there is a need for a unified classification system with an accepted standard terminology for the diagnosis and management of prenatal and postnatal UT dilation.

METHODS

A consensus meeting was convened on March 14-15, 2014, in Linthicum, Maryland, USA to propose: 1) a unified description of UT dilation that could be applied both prenatally and postnatally; and 2) a standardized scheme for the perinatal evaluation of these patients based on sonographic criteria (i.e. the classification system). The participating societies included American College of Radiology, the American Institute of Ultrasound in Medicine, the American Society of Pediatric Nephrology, the Society for Fetal Urology, the Society for Maternal-Fetal Medicine, the Society for Pediatric Urology, the Society for Pediatric Radiology and the Society of Radiologists in Ultrasounds.

RESULTS

The recommendations proposed in this consensus statement are based on a detailed analysis of the current literature and expert opinion representing common clinical practice. The proposed UTD Classification System (and hence the severity of the UT dilation) is based on six categories in US findings: 1) anterior-posterior renal pelvic diameter (APRPD); 2) calyceal dilation; 3) renal parenchymal thickness; 4) renal parenchymal appearance; 5) bladder abnormalities; and 6) ureteral abnormalities. The classification system is stratified based on gestational age and whether the UT dilation is detected prenatally or postnatally. The panel also proposed a follow-up scheme based on the UTD classification.

CONCLUSION

The proposed grading classification system will require extensive evaluation to assess its utility in predicting clinical outcomes. Currently, the grading system is correlated with the risk of postnatal uropathies. Future research will help to further refine the classification system to one that correlates with other clinical outcomes such as the need for surgical intervention or renal function.

Midterm outcomes of protection for upper urinary tract function by augmentation enterocystoplasty in patients with neurogenic bladder

PURPOSE

To evaluate the midterm outcomes of protection for upper urinary tract (UUT) function by augmentation enterocystoplasty (AE) using a grading system for upper urinary tract dilation (UUTD) and a descriptive system for all urinary tract dysfunction (AUTD) in patients with neurogenic bladder.

METHODS

We retrospectively reviewed 120 cases of AE from our database, which was collected between 2005 and 2013. UUTD grading system was developed by magnetic resonance urography (MRU), and AUTD system was described by video-urodynamics, MRU, isotope renography, etc. UUT function was evaluated by these systems before operation, and at 6, 12, 24 and 36 months postoperatively. The indication, midterm outcomes and complications were evaluated.

RESULTS

All patients had significant improvement for urodynamic parameters at 6 months postoperatively. Comparing the grades of UUTD and vesicoureteral reflux (VUR) before and after operation, the median grade of 95 UUTD ureters decreased from 3 to 0, and the percentage of 0 grade UUTD increased from 0 to 90.9 % at 36 months. The median grade of 96 VUR ureters decreased from 3 to 0, and the percentage of 0 grade VUR increased from 0 to 98.6 % at 36 months. The glomerular filtration rate of kidneys and serum creatinine level of patients had an increasing improvement after surgery.

CONCLUSIONS

The midterm follow-up using UUTD and AUTD systems indicates that AE is effective and safe for UUT protection. The patients with moderate and severe UUT deteriorations and renal function impairment resulting from VUR and UUTD have undergone the increasing improvement.

Comparison of the reliability of two hydronephrosis grading systems: the Society for Foetal Urology grading system vs. the Onen grading system

AIM

To compare the reliability of the conventional ultrasonography grading system for hydronephrosis as suggested by the Society for Fetal Urology (SFU) in 1993 and that developed by Onen in 2007.

MATERIALS AND METHODS

One hundred and eighty kidneys in 90 paediatric patients were assessed by four radiologists using each of the two grading systems twice. The SFU system was graded 0-4 (0 = no hydronephrosis; 1 = visualized only renal pelvis; 2 = plus a few caliceal dilatation; 3 = all calyceal dilatation; 4 = plus parenchymal thinning). The Onen system was graded 0-4 (0 = no hydronephrosis; 1 = only renal pelvic dilatation; 2 = plus caliceal dilatation; 3 = plus <50% renal parenchymal loss; 4 = plus >50% renal parenchymal loss). Cohen's kappa statistic was used to estimate intra- and interobserver agreement. The weighted least-squares approach was used to compare the intra-observer agreement, and bootstrapping was used to compare the interobserver agreement between the two systems.

RESULTS

Intra-observer agreement was substantial to almost perfect in both the SFU (κ 0.79-0.95) and the Onen (κ 0.66-0.97) grading system without difference. The overall interobserver agreement was substantial in both the SFU (κ 0.61-0.68) and the Onen (κ 0.66-0.76) grading system. However, interobserver agreement was fair to moderate for SFU grades 1 and 2 and Onen grades 2 and 3.

CONCLUSION

Both the SFU and Onen grading system are reliable with good intra- and interobserver agreement. However, decreased interobserver agreement was demonstrated for SFU grades 1 and 2 and Onen grades 2 and 3.

Comparative evaluation of the resolution of hydronephrosis in children who underwent open and robotic-assisted laparoscopic pyeloplasty

OBJECTIVES

To assess long-term postoperative ultrasonographic outcomes of robotic-assisted laparoscopic pyeloplasty (RALP) and of conventional open pyeloplasty (COP) in pediatric patients with ureteropelvic junction obstruction.

METHODS

Retrospective review of 312 patients who underwent RALP or COP in a single institution. Preoperative and postoperative ultrasounds were used to determine the grade of hydronephrosis. Postoperative assessment included 3 ultrasounds at 0-6, 6-12 and >12 months intervals. Patients were matched by age, etiology of obstruction, grade of preoperative hydronephrosis and gender for case-matched analysis.

RESULTS

We identified 212 pyeloplasties that met inclusion criteria, being 58 RALP and 154 COP. Groups were different in age, gender and etiology, but similar in severity of hydronephrosis and follow-up time. At the end of follow-up, complete resolution and success rates were 62% and 74% in RALP and 45% and 70% in COP, respectively. Matching included 105 patients. Complete resolution was higher in RALP (p = 0.004), while median time before improvement was lower (12.3 months RALP vs 29.9 months COP). There was no difference in success rate at the end of follow-up between the groups.

CONCLUSION

RALP shows satisfactory long-term outcomes, comparable to COP. In our cohort, patients who underwent robotic pyeloplasty showed faster resolution of hydronephrosis on ultrasound.