Severe vesicoureteral reflux and chronic renal failure: a condition peculiar to male gender? Data from the ItalKid Project

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.

Uromodulin and Vesico-Ureteral Reflux: A Genetic Study

Vesicoureteral reflux (VUR) is associated with urinary tract infections (UTI) and renal scars. The kidney damage is correlated with the grade of reflux and the number of UTI, but other factors may also play a role. Uromodulin (UMOD) is a protein produced by kidney tubular cells, forming a matrix in the lumen. We evaluated whether the common variant rs4293393 in the UMOD gene was associated with febrile UTI (FUTI) and/or scars in a group of children with VUR. A total of 31 patients with primary VUR were enrolled. Renal scars were detected in 16 children; no scar was detected in 15 children. Genotype rs4293393 TC (TC) was present in 8 patients, 7 (88%) had scars; genotype rs4293393 TT (TT) was found in 23 patients, and 9 (39%) had scars. Among children with scars, those with TC compared with those with TT were younger (mean age 77 vs. 101 months), their reflux grade was comparable (3.7 vs. 3.9), and the number of FUTI was lower (2.9 vs. 3.7 per patient). Children with VUR carrying UMOD genotype rs4293393 TC seem more prone to developing renal scars, independent of FUTI.

Asian guidelines for urinary tract infection in children

The followings are the level of evidence (LE) and grade of recommendation (GR) on pediatric UTI in Asia. Classification according to the sites of infection (lower versus upper tract), the number of episode (first versus recurrent), the severity (simple versus severe), or the existence of complicating factor (uncomplicated versus complicated) is useful to differentiate children with UTI whether they are at risk of renal damage or not (LE: 2, GR: B). Diagnosis of UTI requires both urinalysis that suggests infection and positive urine culture (LE:3, GR B). For pre-toilet trained children, urine specimen for culture should be collected by urethral catheterization or suprapubic aspiration. For toilet trained children, midstream clean catch urine is reliable (LE: 3, GR: A). Urine culture is considered positive if it demonstrates growth of a single bacterium with the following colony counts: (1) any growth by suprapubic aspiration, (2) >5 × 104 CFU/ml by urethral catheterization, or (3) >105 CFU/ml by midstream clean catch (LE:3, GR: B). For children with febrile UTI, renal and bladder ultrasonography (RBUS) should be routinely performed as soon as possible (LE: 3, GR: C). RBUS should be followed up 6 months later in children with acute pyelonephritis and/or VUR (LE: 3, GR: C). Acute DMSA scan can be performed when severe acute pyelonephritis or congenital hypodysplasia is noted on RBUS or when the diagnosis of UTI is in doubt by the clinical presentation (LE: 3, GR: C). Late DMSA scan (>6 months after the febrile UTI) can be performed in children with severe acute pyelonephritis, high-grade VUR, recurrent febrile UTIs, or abnormal renal parenchyma on the follow-up RBUS (LE: 3, GR: C). Top-down or bottom-up approach for febrile UTI is suggested for the diagnosis of VUR. For top-down approach, VCUG should not be performed routinely for children after the first febrile UTI. VCUG is indicated when abnormalities are apparent on either RBUS or DMSA scan or both (LE: 2, GR: B). VCUG is also suggested after a repeat febrile UTI (LE:2, GR: B). Appropriate antibiotic should be given immediately after urine specimen for culture has been obtained (LE:2, GR: A). Initiating therapy with oral or parenteral antibiotics is equally efficacious for children (>3 months) with uncomplicated UTI (LE: 2: GR: A). The choice of empirical antibiotic agents is guided by the expected pathogen and the local resistance patterns (LE: 2, GR: A). For children with febrile UTI, the total course of antibiotic therapy should be 7-14 days (LE: 2, GR: B). Circumcision may, but not definitively, reduce the risk of febrile UTI in males and breakthrough febrile UTI in males with VUR. Circumcision should be offered to uncircumcised boys with febrile UTI and VUR in countries where circumcision is accepted by the general population (LE: 3, GR: B), while in countries where childhood circumcision is rarely performed, other measures for febrile UTI/VUR should be the preferred choice (LE: 4, GR: C). Bladder bowel dysfunction (BBD) is one of the key factors of progression of renal scarring (LE: 2). Early recognition and management of BBD are important in prevention of UTI recurrence (LE:2, GR: A). Antibiotic prophylaxis to prevent recurrent febrile UTI is indicated in children with moderate to high grade (III-V) VUR (LE: 1b, GR: A). Surgical intervention may be used to treat VUR in the setting of recurrent febrile UTI because it has been shown to decrease the incidence of recurrent pyelonephritis (LE: 2, GR: B).

Is endothelial glycocalyx damage a cause of renal scarring in vesicoureteral reflux with febrile urinary tract infection?

INTRODUCTION

Endothelial glycocalyx is a luminal layer which can be damaged by inflammatory agents or pathogens. The endothelial glycocalyx damage is thought to have a role in the formation of renal scars in children who have febrile urinary tract infection and vesicoureteral reflux. This study aimed to compare the blood levels of endothelial glycocalyx components heparan sulfate and Syndecan-1 in children with and without renal scarring due to vesicoureteral reflux-associated febrile urinary tract infection.

MATERIALS AND METHODS

Data of the patients diagnosed with vesicoureteral reflux without renal scarring (Group 1), patients with vesicoureteral reflux and renal scarring (Group 2), and completely healthy children (Group 3) were retrospectively reviewed. Blood levels of heparan sulfate and Syndecan-1 were measured and the results were compared.

RESULTS

The entire cohort consisted of 90 patients; there were 30 patients in each group. Mean patient age was 49.7±18.0 months. Mean serum heparan sulfate (42.90±18.90 ng/mL) and Syndecan-1 (37.59±13.77 ng/mL) levels of Group 2 were significantly higher than those of other groups. The cut-off value for heparan sulfate was 35.17 ng/mL, with a 63% sensitivity and 86% specificity. The cut-off value for Syndecan-1 was 29.99 ng/mL with a 70% sensitivity and 80% specificity.

CONCLUSION

Our findings indicate that blood levels of heparan sulfate and Syndecan-1 could be related with renal scarring in patients with vesicoureteral reflux, especially in the setting of febrile urinary tract infection. However, due to their low sensitivity, these biomarkers should be used along with clinical data.

Kidney structure and function in dilating vesicoureteral reflux patients with anorectal malformation

Background

We assessed the impact of anorectal malformation (ARM) on the kidneys of children with dilating vesicoureteral reflux (D-VUR) ≥grade III using a simple dimercaptosuccinic acid (DMSA) scintigraphy scan based renal dysfunction score (RDS).

Methods

The medical records of 121 patients with D-VUR treated between 2000 and 2014 were reviewed retrospectively. After excluding patients with secondary D-VUR (n=18), presence of ARM was used to create two groups: ARM+ (n=12 cases; 15 ureters) and ARM– (n=91 cases; 131 ureters). Types of ARM, grades of D-VUR, bladder and bowel dysfunction (BBD) and RDS were compared.

Results

Patient demographics, mean follow-up, grades of D-VUR and history of urinary tract infections were not significantly different. BBD was significantly higher in ARM+ (41.7% versus 7.7%, p=0.0006). RDS was significantly higher in ARM+ (p=0.036). Grades of D-VUR were significantly lower in ARM– with low RDS (p=0.008). During follow-up, changes in DMSA uptake over time were not observed in ARM+.

Conclusions

While renal cortical lesions were correlated with grade of D-VUR in ARM– and RDS was significantly higher in ARM+, BBD did not appear to contribute to progressive renal dysfunction as is commonly believed. In fact, no progression in renal cortical lesions was observed in ARM+ based on RDS data. Renal cortical lesions may possibly be a feature of ARM, a topic that warrants further study.

Contrast-enhanced voiding urosonography with intravesical administration of ultrasound contrast agent for the diagnosis of pediatric vesicoureteral reflux

Vesicoureteral reflux (VUR) is one of the most common urinary tract anomalies in children. It has been reported that VUR may be associated with reflux nephropathy. Ultrasound contrast-enhanced voiding urosonography (CeVUS) has become a routine diagnostic method for VUR in a number of European countries; however, it is not widely used in China. The aim of the present study was to analyze the clinical application and evaluate the safety of CeVUS as a diagnostic tool for VUR in children in order to establish a standardized operating procedure for CeVUS in pediatric VUR in China. Between August 2016 and October 2017, 90 children who were susceptible to VUR were admitted into the Pediatric Nephrology Department of Tongji Hospital and underwent CeVUS. The SonoVue second-generation USA contrast agent was administered intravesically via a transurethral bladder catheter at a dose of 1 ml. The occurrence of adverse events was monitored. Urine analysis and culture were performed. A total of 90 children (47 female, 43 male; mean age, 36.6 months) with 178 Pelvi-Ureteral Units (PUUs) underwent CeVUS to screen for VUR. VUR was detected in 44/90 pediatric patients (48.89%) and 65/178 PUUs (36.52%) by CeVUS. The grade distribution of the 65 PUUs with VUS was as follows: Grade I, 3; Grade II, 9; Grade III, 14; Grade IV, 22; and Grade V, 17. The accuracy of CeVUS in the present study were consistent with previous reports. No urethral anomalies were detected and there were no adverse events. CeVUS was demonstrated to be a safe, accurate and reliable imaging technique for detecting VUR in high-risk children, including neonates. Results of the present study indicated that CeVUS can be adopted as the primary screening and follow-up method for pediatric VUR diagnoses in China.

Delayed diagnosis of primary vesicoureteral reflux in children with recurrent urinary tract infections: Diagnostic approach and renal outcomes

OBJECTIVE

In this study, we aimed to assess renal outcomes of delayed diagnosis of dilating primary vesicoureteral reflux (VUR) following recurrent febrile urinary tract infections (fUTIs) and its diagnostic imaging procedures.

MATERIAL AND METHODS

The medical records of patients who underwent ultrasonography (US), non- acute dimercaptosuccinic acid (Tc-99mDMSA) scintigraphy and voiding cystourethrography (VCUG), and who were older than 2 years at the time of VUR diagnosis were retrospectively reviewed.

RESULTS

A total of 32 children (female, n=27: 84.4%) with a mean age of 7.67±3.34 years at the time of diagnosis of VUR were included in the study. Grade III, IV, V VUR were found in 22%, 69%, and 9% of the patients, respectively. At the time of VUR diagnosis, abnormal US findings were detected in 75% of the cases. Tc-99mDMSA detected abnormalities in 83.9% (7 with a single scar, 7 with multiple lesions, 12 with reduced kidney function) of the patients. Estimated glomerular filtration rate of 3 patients with bilateral grade IV VUR was <75 mL/min/1.73 m². In 5 patients (16%), VUR could not be predicted by US+DMSA scintigraphy (Grade IV VUR in 3 and Grade III in 2 cases ). The sensitivity in predicting VUR was 75.00% (95% CI: 56.60-88.54) and 83.87% (95% CI: 66.27-94.55), respectively, for US alone and combined US+DMSA.

CONCLUSION

VCUG should be performed routinely in addition to US and non-acute DMSA in all children referred with recurrent fUTIs. Awareness of childhood UTI in public and healthcare personnels should be increased in order to refer these patients at a early stage to pediatric urology and nephrology units.

Endoscopic injection for primary vesicoureteric reflux: Predictors of resolution and long term efficacy

AIM

We investigated the efficacy of endoscopic-Deflux-injection in treating primary-vesicoureteric-reflux (VUR) and identified factors to predict resolution.

MATERIALS AND METHODS

Records of children treated with Deflux for primary-VUR from 1995 to 2016 were reviewed, and outcomes were investigated.

RESULTS

Eighty-eight ureters (35 bilateral, 18 unilateral) in 53 children underwent 124 injections. Thirty-five (66%) patients had single injection (13 unilateral, 22 bilateral). Fifteen (28%), two (37%), and one (2%) patients had two, three, and four injections, respectively. Overall success rate by ureters was 57% after single injection. Complete resolution occurred in 65% of ureters with VUR below grade III, 63% of grade III, 40% of grade IV, and 70% of grade V VUR. Four patients had reimplantation. The median follow up duration was 60months (range 20-216months). Univariate analysis showed that lower VUR grade (p=0.03) and absent renal scars (p=0.04) were statistically significant predictors of resolution. In multivariate analysis, absent renal scars were statistically significant (p=0.01).

CONCLUSION

We demonstrated efficacy of endoscopic-Deflux-injection as the first line treatment for primary-VUR. Absent renal scar and lower VUR grade were statistically significant predictors of resolution after single injection.

TYPE OF STUDY

Case-Control / Retrospective Comparative Study.

LEVEL OF EVIDENCE

Level III.

Summary of the UAA-AAUS guidelines for urinary tract infections

Urinary tract infections, genital tract infections and sexually transmitted infections are the most prevalent infectious diseases, and the establishment of locally optimized guidelines is critical to provide appropriate treatment. The Urological Association of Asia has planned to develop the Asian guidelines for all urological fields, and the present urinary tract infections, genital tract infections and sexually transmitted infections guideline was the second project of the Urological Association of Asia guideline development, which was carried out by the Asian Association of Urinary Tract Infection and Sexually Transmitted Infection. The members have meticulously reviewed relevant references, retrieved via the PubMed and MEDLINE databases, published between 2009 through 2015. The information identified through the literature review of other resources was supplemented by the author. Levels of evidence and grades of recommendation for each management were made according to the relevant strategy. If the judgment was made on the basis of insufficient or inadequate evidence, the grade of recommendation was determined on the basis of committee discussions and resultant consensus statements. Here, we present a short English version of the original guideline, and overview its key clinical issues.

Renal scar formation and kidney function following antibiotic-treated murine pyelonephritis

We present a new preclinical model to study treatment, resolution and sequelae of severe ascending pyelonephritis. Urinary tract infection (UTI), primarily caused by uropathogenic Escherichia coli (UPEC), is a common disease in children. Severe pyelonephritis is the primary cause of acquired renal scarring in childhood, which may eventually lead to hypertension and chronic kidney disease in a small but important fraction of patients. Preclinical modeling of UTI utilizes almost exclusively females, which (in most mouse strains) exhibit inherent resistance to severe ascending kidney infection; consequently, no existing preclinical model has assessed the consequences of recovery from pyelonephritis following antibiotic treatment. We recently published a novel mini-surgical bladder inoculation technique, with which male C3H/HeN mice develop robust ascending pyelonephritis, highly prevalent renal abscesses and evidence of fibrosis. Here, we devised and optimized an antibiotic treatment strategy within this male model to more closely reflect the clinical course of pyelonephritis. A 5-day ceftriaxone regimen initiated at the onset of abscess development achieved resolution of bladder and kidney infection. A minority of treated mice displayed persistent histological abscess at the end of treatment, despite microbiological cure of pyelonephritis; a matching fraction of mice 1 month later exhibited renal scars featuring fibrosis and ongoing inflammatory infiltrates. Successful antibiotic treatment preserved renal function in almost all infected mice, as assessed by biochemical markers 1 and 5 months post-treatment; hydronephrosis was observed as a late effect of treated pyelonephritis. An occasional mouse developed chronic kidney disease, generally reflecting the incidence of this late sequela in humans. In total, this model offers a platform to study the molecular pathogenesis of pyelonephritis, response to antibiotic therapy and emergence of sequelae, including fibrosis and renal scarring. Future studies in this system may inform adjunctive therapies that may reduce the long-term complications of this very common bacterial infection.

Summary: A new model of antibiotic-treated severe pyelonephritis offers a novel platform to study the molecular pathogenesis of pyelonephritis, response to antibiotic therapy, and sequelae, including fibrosis and renal scarring.

The Swedish infant high-grade reflux trial: UTI and renal damage

INTRODUCTION

High-grade vesicoureteral reflux (VUR) in children is associated with recurrent urinary tract infection (UTI) and renal damage. Breakthrough UTI despite continuous antibiotic prophylaxis (CAP) during the first years of life is a matter of concern and evokes early intervention. We investigated whether early endoscopic treatment (ET) of VUR grade 4-5 can reduce the risk of UTI recurrence and renal scarring.

MATERIALS AND METHODS

This prospective, randomized, controlled, multicentre, 1-year follow-up trial comprised 77 infants, <8 months of age with VUR grade 4-5 (Table) randomized to CAP (n = 39) or ET (with prophylaxis until resolution) (n = 38). Voiding cystourethrogram, ultrasound, renal scintigraphy, and free voiding observation were performed at study entry and after 1 year. Parenchymal defects were seen in 67 (87%) children at entry, 39 (34 boys, 5 girls) of them characterized as generalized. At follow-up, renal deterioration (new scars or progress in old damaged area) and symptomatic UTIs were reported.

RESULTS

There were 27 recurrent febrile UTIs in 6 (16%) children in the ET group and in 10 (26%) in the CAP group (p = 0.43), in eight (36%) girls and eight (15%) boys (p = 0.039). Successful VUR outcome (VUR 0-2) was seen in 22 (59%) in the ET and eight (21%) in the CAP group (p = 0.0014). Multiple recurrences were only seen in patients with persistent dilating reflux at follow-up (p = 0.019). Deterioration on scintigraphy was seen in eight children (9 kidneys) with no difference between treatment groups (p = 0.48) or sex (p = 0.17). Renal deterioration was associated with high bladder capacity (BC) and large residual volume (PVR) at 1 year (p = 0.0092 and p = 0.041). Six of the eight children with renal deterioration had a recurrent UTI (p = 0.0032). Seven of nine renal units with deterioration were seen in children with persistent VUR 3-5 at follow-up. Univariable logistic regression identified female sex and high PVR as positive predictors for recurrent UTI (p = 0.039 and 0.034) and high PVR tended to predict renal deterioration (p = 0.053).

DISCUSSION

No differences between the treatment groups regarding recurrent UTI and renal deterioration could be found. Increased PVR and female sex were positive predictors for UTI recurrences. VUR grade at follow-up was correlated to UTI recurrence and renal deterioration.

CONCLUSION

This study did not show any difference between ET and CAP in reducing the risk of UTI recurrence or renal deterioration. The rate of VUR resolution was higher in the ET group and VUR grade at follow-up correlated with both UTI recurrence and renal deterioration.

Vesicoureteral refux detection in children: a comparison of the midline-to-orifice distance measurement by ultrasound and voiding urosonography

BACKGROUND

Due to the questionable clinical role of vesicoureteral reflux (VUR) and the search for noninvasive, radiation-free procedures sufficiently reliable to detect VUR, we compared the correlation between the midline-to-orifice distance (MOD) measured by ultrasonography (US) and echo-enhanced voiding urosonography (VUS) for detecting VUR in children. The aim of the study was to determine whether measuring MOD by US could be a reliable predictor of VUR in children.

METHODS

A total of 116 children, aged 0.25-84 months, with 232 potentially refluxing units were investigated simultaneously by measuring the MOD and performing VUS. Indications for cystography were urinary tract infection and follow-up of a previously detected VUR. VUS was performed after the MOD measurement. The results were analyzed with VUS as the reference method.

RESULTS

The MOD was significantly larger in VUR grade III (10.7 mm; p = 0.003) and VUR grade II (9.9 mm; p = 0.001) refluxing units than in non-refluxing units (7.8 mm), even when controlling for the estimated volume/expected maximal capacity (Vest/Vmax) ratio. A MOD cutoff value of 7.4 mm was chosen as a predictor of either the presence or absence of VUR; the sensitivity and specificity of this cutoff measurement for VUR detection were found to be 89 and 24%, respectively.

CONCLUSIONS

Despite the statistically significant difference between the MOD of refluxing versus non-refluxing units identified in our study, the MOD measurement needs further evaluation to determine its potential value as a diagnostic tool for the detection of VUR.

Genetics of Vesicoureteral Reflux

Vesicoureteral reflux (VUR) is the retrograde passage of urine from the bladder to the upper urinary tract. It is the most common congenital urological anomaly affecting 1-2% of children and 30-40% of patients with urinary tract infections. VUR is a major risk factor for pyelonephritic scarring and chronic renal failure in children. It is the result of a shortened intravesical ureter with an enlarged or malpositioned ureteric orifice. An ectopic embryonal ureteric budding development is implicated in the pathogenesis of VUR, which is a complex genetic developmental disorder. Many genes are involved in the ureteric budding formation and subsequently in the urinary tract and kidney development. Previous studies demonstrate an heterogeneous genetic pattern of VUR. In fact no single major locus or gene for primary VUR has been identified. It is likely that different forms of VUR with different genetic determinantes are present. Moreover genetic studies of syndromes with associated VUR have revealed several possible candidate genes involved in the pathogenesis of VUR and related urinary tract malformations. Mutations in genes essential for urinary tract morphogenesis are linked to numerous congenital syndromes, and in most of those VUR is a feature. The Authors provide an overview of the developmental processes leading to the VUR. The different genes and signaling pathways controlling the embryonal urinary tract development are analyzed. A better understanding of VUR genetic bases could improve the management of this condition in children.

Vesicoureteral Reflux Detected with (99m)Tc-DTPA Renal Scintigraphy during Evaluation of Renal Function

BACKGROUND:

Radionuclide techniques, as direct radionuclide cystography and ^99mTc-DMSA scintigraphy, have been used in evaluation of vesicoureteral reflux (VUR) and reflux nephropathy (RN) in children. Dynamic ^99mTc-DTPA scintigraphy is reserved for evaluation of differential renal function and obstruction in children, where hydronephrosis is detected by ultrasonography (US) pre- or postnatally.

CASE REPORT:

Six year old boy was prenatally diagnosed with bilateral hydronephrosis. Postnatal, severe bilateral VUR was detected by voiding urethrocytography. US and ^99mTc-DTPA scintigraphy performed in the first month of life showed small left kidney that participated with 2% in the global renal function. Bilateral cutaneous ureterostomy has been performed in order to obtain good renal drainage and promote optimal renal growth. Twelve months later, classic antireflux procedure was done. Control ^99mTc-DTPA scintigraphy, 5 ys after antireflux surgery, revealed persisting radioactivity during the diuretic phase, in the left kidney that indicated antireflux procedure failure with VUR reappearance.

CONCLUSION:

^99mTc-DTPA scintigraphy is the first method of choice for long-term monitoring of individual kidney function in children with VUR and other congenital urinary tract anomalies. Additionally, it can be used as indirect radionuclide cystography when rising of radioactivity in the kidney region, during the diuretic phase can indicate presence of VUR.

Renal ultrasound and DMSA screening for high-grade vesicoureteral reflux

BACKGROUND

Selection of the appropriate radiologic investigation in a child after first febrile urinary tract infection (UTI) remains a contentious issue. This report investigated the effectiveness of renal bladder ultrasound (RBUS) and late 6 month dimercaptosuccinic acid (DMSA) renal scan in the detection of high-grade vesicoureteral reflux (VUR) after first febrile UTI in infants aged <1 year.

METHODS

A total of 387 infants aged <1 year with first febrile UTI who completed diagnostic follow up consisting of RBUS, voiding cystourethrogram (VCUG) and late 6 month DMSA scan were enrolled in the study. The effectiveness of RBUS and DMSA scan in the detection of high-grade VUR, including cost and benefit were assessed.

RESULTS

Abnormal RBUS was identified in 95 infants (24.5%). VUR was identified on VCUG in 79 (20.4%), of whom eight (2.1%) had high-grade VUR (grade IV-V). Abnormal renal parenchyma was identified on late 6 month DMSA scan in 22 infants (5.7%). The sensitivity of abnormal RBUS and of late 6 month DMSA scan in the prediction of high-grade VUR was 50% and 87.5%, and the proportion of infants who avoided unnecessary VCUG was 75.5% and 94.3%, respectively.

CONCLUSIONS

Fifty percent of high-grade VUR was not identified on RBUS screening after first febrile UTI. Although late 6 month DMSA scan had higher sensitivity in the detection of high-grade VUR, with the added benefit of detection of renal scars, the practical application of this method was limited due to its high cost, radiation exposure and the associated delay in decision making.

Segmentation of renal parenchymal area from ultrasound images using level set evolution

This paper presents a framework for segmentation of renal parenchymal area from ultrasound images based on a 2-step level set method. We used distance regularized level set evolution method to partition the kidney boundary, followed by region-scalable fitting energy minimization method to segment the kidney collecting system, and determined renal parenchymal area by subtracting the area of the collecting system from the gross kidney area. The proposed method demonstrated excellent validity and low inter-observer variability.

Renal parenchymal area and risk of ESRD in boys with posterior urethral valves

BACKGROUND AND OBJECTIVES

Approximately 20% of boys with posterior urethral valves develop ESRD; however, few factors associated with the risk of ESRD have been identified. The objective of this study was to determine if renal parenchymal area, defined as the area of the kidney minus the area of the pelvicaliceal system on first postnatal ultrasound, is associated with the risk of ESRD in infants with posterior urethral valves.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective cohort of boys who were diagnosed with posterior urethral valves at less than 6 months of age between 1988 and 2011 and followed for at least 1 year at a free-standing children's hospital was assembled. Cox proportional hazard regression and Kaplan-Meier analysis were used to estimate the association between renal parenchymal area and time to ESRD. Cox models were adjusted for age at presentation, minimum creatinine 1 month after bladder decompression, and vesicoureteral reflux.

RESULTS

Sixty patients were followed for 393 person-years. Eight patients developed ESRD. Median renal parenchymal area was 15.9 cm(2) (interquartile range=13.0-21.6 cm(2)). Each 1-cm(2) increase in renal parenchymal area was associated with a lower risk of ESRD (hazard ratio, 0.64; 95% confidence interval, 0.42 to 0.98). The rate of time to ESRD was 10 times higher in boys with renal parenchymal area<12.4 cm(2) than boys with renal parenchymal area≥12.4 cm(2) (P<0.001). Renal parenchymal area could best discriminate children at risk for ESRD when the minimum creatinine in the first 1 month after bladder decompression was between 0.8 and 1.1 mg/dl.

CONCLUSION

In boys with posterior urethral valves presenting during the first 6 months of life, lower renal parenchymal area is associated with an increased risk of ESRD during childhood. The predictive ability of renal parenchymal area, which is available at time of diagnosis, should be validated in a larger, prospectively-enrolled cohort.

Childhood vesicoureteral reflux studies: registries and repositories sources and nosology

Despite several recent studies, the advisability of antimicrobial prophylaxis and certain imaging studies for urinary tract infections (UTIs) remains controversial. The role of vesicoureteral reflux (VUR) on the severity and re-infection rates for UTIs is also difficult to assess. Registries and repositories of data and biomaterials from clinical studies in children with VUR are valuable. Disease registries are collections of secondary data related to patients with a specific diagnosis, condition or procedure. Registries differ from indices in that they contain more extensive data. A research repository is an entity that receives, stores, processes and/or disseminates specimens (or other materials) as needed. It encompasses the physical location as well as the full range of activities associated with its operation. It may also be referred to as a biorepository. This report provides information about some current registries and repositories that include data and samples from children with VUR. It also describes the heterogeneous nature of the subjects, as some registries and repositories include only data or samples from patients with primary reflux while others also include those from patients with syndromic or secondary reflux.

Different imaging strategies in febrile urinary tract infection in childhood. What, when, why?

Urinary tract infections (UTIs) are a common problem in childhood. During the last decade, published papers led to a deep revision in the use and usefulness of imaging tools in children with febrile UTIs. This new body of knowledge was partially endorsed by the guidelines published in 2007 by the UK's National Institute for Clinical Excellence and in 2011 by the American Academy of Pediatrics. Nevertheless, new data continuously arise and the scientific debate always revives. Recommendations of published guidelines and strengths and weaknesses of the available biochemical and imaging tools are here critically analysed for giving to the reader a complete, up-to-date and flexible overview on this hot topic.

Intraureteral injection of NASHA/Dx gel under direct ureteroscopic visualization for the treatment of primary high-grade vesicoureteral reflux

OBJECTIVE

To present a preliminary experience with the modified technique of extravesical intraureteral injection of non-animal-stabilized hyaluronic acid/dextranomer (NASHA/Dx) gel under direct ureteroscopic visualization for the treatment of primary high-grade vesicoureteral reflux (VUR).

PATIENTS AND METHODS

The medical records of all pediatric patients (age range, 0-14 years) who underwent intraureteral injection of NASHA/Dx gel under direct ureteroscopic visualization for the treatment of primary high-grade VUR during the period June 2006-June 2010 were reviewed.

RESULTS

Eighty-nine children (61 boys, 28 girls; M:F ratio, 2.1) underwent intraureteral injection of NASHA/Dx gel under direct ureteroscopic visualization for the treatment of primary high-grade VUR during the study period. VUR completely disappeared after the injection of NASHA/Dx gel into 105 (73%) of 144 ureters, with no further treatment required. Thirty-five (24.3%) required a second injection, and 2 (1.4%) required a third injection for resolution of their VUR. No intraoperative complications were observed. No ureteral obstruction during follow-up was observed using ultrasound or micturition studies.

CONCLUSIONS

Intraureteral injection of NASHA/Dx gel under direct ureteroscopic visualization is safe and effective in the treatment of primary high-grade VUR, including cases with ureteral duplication, if the ureteral meatus is easy to pass through without mechanical dilation. This approach represents an effective and safe alternative to antibiotic prophylaxis alone and open surgery.

Familial vesicoureteral reflux and reflux related morbidity in relatives of index patients with high grade vesicoureteral reflux

PURPOSE

The familial nature of vesicoureteral reflux is well recognized. However, there is little information about the prevalence of vesicoureteral reflux and reflux related morbidity in the relatives of index patients with vesicoureteral reflux. Therefore, we determined the prevalence of vesicoureteral reflux and reflux related morbidity in first, second and third-degree relatives of index patients with high grade vesicoureteral reflux.

MATERIALS AND METHODS

Between 1998 and 2010 the parents of 259 index patients with grade III-V vesicoureteral reflux were asked permission to screen siblings younger than age 6 years for vesicoureteral reflux. Parents of index patients with affected siblings were contacted to obtain detailed information regarding vesicoureteral reflux, recurrent urinary tract infections, end stage renal disease, hypertension and nephrectomy among first, second and third-degree relatives.

RESULTS

A total of 300 siblings of the 259 index patients were found to have vesicoureteral reflux on voiding cystourethrography. In terms of the other relatives of the 259 index patients 127 also had radiologically proven vesicoureteral reflux. Reflux related morbidity among the first, second and third-degree relatives included end stage renal disease in 21, nephrectomy in 12 and hypertension in 4. Of the 212 siblings who had dimercapto-succinic acid scans 49 (23.1%) showed evidence of renal scarring. In 73% of the relatives vesicoureteral reflux was seen on the mother's side.

CONCLUSIONS

This study, the first to our knowledge, provides important information regarding reflux related morbidity in a large cohort of familial vesicoureteral reflux in first, second and third-degree relatives of index patients. Our data clearly show that there is an increased risk of reflux related morbidity among the relatives of index patients with vesicoureteral reflux and this finding has implications for counseling.

Natural history of bilateral mild isolated antenatal hydronephrosis conservatively managed

BACKGROUND

The purpose of this study was to assess the prevalence and outcome of newborns with bilateral mild isolated antenatal hydronephrosis managed with neither antibiotic prophylaxis nor voiding cystourethrography (VCUG).

METHODS

Inclusion criteria were ultrasonographic evidence of an anterior-posterior pelvic diameter (APPD) of 5-15 mm at the third trimester of gestation and on the first postnatal ultrasound sonogram. Exclusion criteria were an APPD >15 mm, calyectasis, hydroureteronephrosis, or renal or bladder abnormalities. Ultrasound follow-up was performed. Parents were familiarized with the signs of urinary tract infection (UTI). If UTI was confirmed, VCUG was performed. The outcome was assessed as intrauterine resolution of hydronephrosis, total or partial resolution, stability, or progression.

RESULTS

Hydronephrosis was bilateral in 98 of the 236 newborns (196 hydronephrotic kidneys) with mild isolated antenatal hydronephrosis enrolled in this study. Nine patients had UTI, and none showed reflux. After a mean follow-up of 15 months, 74 kidneys showed intrauterine resolution (38%), 82 (42%) showed total resolution, 13 showed partial resolution, 24 were stable, and 3 showed progression. Bilateral cases represented 42% of mild isolated antenatal hydronephrosis. During the first year of life, 80% of the kidneys showed total hydronephrosis resolution, 9% of patients had UTI, and none of the patients showed reflux.

CONCLUSIONS

Antibiotic prophylaxis and VCUG are not mandatory in newborns with bilateral mild isolated antenatal hydronephrosis, but clinical and ultrasound follow-up are recommended during the first year of life.

Incidence of febrile urinary tract infections in children after successful endoscopic treatment of vesicoureteral reflux: a long-term follow-up

OBJECTIVE

To evaluate the incidence of febrile urinary tract infection (UTI) after successful endoscopic correction of intermediate and high-grade vesicoureteral reflux (VUR).

STUDY DESIGN

Medical records of 1271 consecutive children (male, 411; female, 903) who underwent successful endoscopic correction of VUR were reviewed. Factors potentially influencing postoperative UTIs, such as history of presentation, age, sex, grade of VUR, renal scarring, and agent used for the endoscopic injection, were analyzed.

RESULTS

Febrile UTI developed in 73 children (5.7%) after successful endoscopic correction of VUR. Thirty-nine children had a single episode of UTI, and 34 children had two or more episodes at 1 month to 5.9 years (median, 1 year) after correction of VUR. With multivariate analysis, female sex (P < .001), history of preoperative bladder/bowel dysfunction (BBD; P = .005), and BBD after endoscopic correction (P = .001) were revealed to be the most important independent risk factors for a febrile UTI after successful correction of VUR.

CONCLUSIONS

The incidence of febrile UTIs after successful correction of intermediate and high grade VUR is low. Female sex and BBD were the most important risk factors in the development of febrile UTI. Our data supports the importance of assessing bladder and bowel habits in older children with febrile UTIs after endoscopic correction of VUR.

A comparison of echo-enhanced voiding urosonography with X-ray voiding cystourethrography in the first year of life

BACKGROUND

Second-generation echo-enhanced voiding urosonography (VUS) with improved contrast-specific ultrasound (US) techniques is increasingly being used for vesicoureteric reflux (VUR) detection.

AIM

To compare VUS with X-ray voiding cystourethrography (VCUG) and to evaluate the predictive value of pelvicalyceal dilatation for detecting VUR in the first year of life.

MATERIALS AND METHODS

Sixty-six children younger than one were investigated by US, VUS and VCUG. VCUG represented the reference method for VUR detection.

RESULTS

According to VCUG, VUR was present in 16/132 (12%) renal units. VUS confirmed all these and additionally revealed VUR in 26 renal units (all together 42/132 (32%) renal units with VUR). It should be noted that all VUR detected only with VUS and missed by VCUG were of grades II and III. In 27/92 (29%) US normal and in 15/40 (37%) renal units with pelvicalyceal dilatation, VUR was detected by VUS.

CONCLUSION

We believe that VUS could safely replace VCUG in VUR detection in infants, with no regard to the degree of abnormality of the upper urinary tract seen on US. VCUG should be limited only to cases where bladder and/or urethra pathology are suspected.

Short-term outcome of mild isolated antenatal hydronephrosis conservatively managed

OBJECTIVES

To assess the outcome of newborns with mild isolated antenatal hydronephrosis (MIAHN) managed with neither antibiotic prophylaxis nor voiding cystourethrography (VCUG).

INCLUSION CRITERIA

anterior-posterior pelvic diameter 5-15 mm at third trimester of gestation, confirmed by first postnatal ultrasound.

EXCLUSION CRITERIA

pelvic diameter > 15 mm, calyectasis, hydroureteronephrosis, renal or bladder abnormalities. Clinical and ultrasound follow-up was performed. Parents were familiarized with urinary tract infection (UTI) signs. If UTI was confirmed, VCUG was performed. Hydronephrosis outcome was assessed as intrauterine resolution, total or partial resolution, stability or progression.

RESULTS

MIAHN was detected in 193 newborns (109 unilateral, 84 bilateral; 277 renal units); 23 (12%) had UTI and 2 of them showed low-grade reflux. After a mean follow-up of 15 months, 91 renal units showed intrauterine resolution (33%), 111 (40%) total resolution, 20 (7%) partial resolution, 52 (19%) stability and 3 (1%) progression.

CONCLUSION

Total resolution of hydronephrosis was observed in 73% of renal units during the first year. Routine antibiotic prophylaxis and VCUG might not be necessary in all infants with MIAHN, clinical and ultrasound follow-up being advisable during the first year of life.

The impact of vesicoureteral reflux treatment on the incidence of urinary tract infection

Vesicoureteral reflux (VUR) is a heterogeneous disease and its management remains one of the most controversial topics in pediatrics. Management options include surveillance, antibiotics, and surgery. The approval of dextranomer/hyaluronic acid (DHA) as a bulking agent by the Food and Drug Administration was followed by wide acceptance of endoscopic techniques as a major tool in the management of reflux. Pyelonephritis rather than VUR is the most common cause of kidney damage in children. It should be emphasized that the primary goal of diagnosing and treating VUR should be preventing this complication. There are no sufficient data in the literature to address the impact of the different treatment modalities on the incidence of febrile urinary tract infections (feb-UTIs) denoting pyelonephritis, with very few studies evaluating endoscopic treatment in light of this clear and well-defined outcome. The fact that we can correct the anatomy at the vesicoureteral junction with a simple and relatively safe outpatient procedure does not justify offering it to all patients. In this review, we attempt to critically evaluate the available literature pertaining to the impact of different treatment modalities on reducing the incidence of febrile UTIs and kidney damage, with a special emphasis on endoscopic treatment.

Managing children under 36 months of age with febrile urinary tract infection: a new approach

BACKGROUND

Recent guidelines on urinary tract infection (UTI) agree on reducing the number of invasive procedures. None of these has been validated by a long-term study. We describe our 11-years experience in the application of a diagnostic protocol that uses a reduced number of invasive procedures.

METHODS

We reviewed retrospectively the records of 406 children aged between 1 and 36 months at their first UTI. All patients underwent renal ultrasound (RUS). Children with abnormal RUS and those with UTI recurrences underwent voiding cystourethrography (VCUG) and dimercaptosuccinic acid (DMSA) renal scans.

RESULTS

RUS after the first UTI was pathological in 7.4% children; 4.4 % had a second UTI. We performed 48 VCUG: 14 patients (29%) had vesicoureteral reflux (VUR), 12 of which showed an abnormal RUS while 2 had recurrent UTI. After DMSA renal scan renal damage appeared in only 6 of them (12.5%); all these children showed grade IV VUR.

CONCLUSIONS

The application of our guidelines leads to a decrease in invasive examinations without missing any useful diagnoses or compromising the child's health.

Urinary tract anomalies associated with high grade primary vesicoureteral reflux

BACKGROUND

Few studies have evaluated the significance of associated urological anomalies in vesicoureteral reflux (VUR). The aim of our study was to determine the incidence of associated urological anomalies in patients with high grade VUR and to assess their impact on renal parenchymal scarring.

METHODS

We retrospectively reviewed the hospital records of 1,765 consecutive cases diagnosed with high grade VUR (Grade III-V) at our hospital between 1998 and 2010. The diagnosis of VUR was made by a voiding cystourethrogram (VCUG). Renal scarring was evaluated by dimercapto-succinic acid (DMSA) scintigraphy and classified into three groups: mild (focal defects in uptake between 40 and 45%), moderate (uptake of renal radionuclide between 20 and 40%), and severe (shrunken kidney with relative uptake <20%). All associated urological anomalies were diagnosed by ultrasound or VCUG or DMSA scan.

RESULTS

Associated urological anomalies were present in 229 (13%) children. There were 87 boys and 142 girls. Duplex kidney was the main associated anomaly occurring in 148 (64.6%) of the 229 patients. Other anomalies were: bladder diverticulum in 29, solitary kidney in 12, ureterocele in 13, hypospadiasis in 11, pelviureteric junction obstruction in 9, malrotated kidney in 3, horseshoe kidney in 2, crossed fused ectopia in 1 and renal cyst in 1. DMSA scan revealed renal scarring in 105 (47.7%) of the 220 children who had a DMSA scan. 75 (50.7%) children with duplex kidneys showed renal scarring.

CONCLUSION

Associated urological anomalies occur commonly in patients with high grade VUR. Our data shows that nearly half of the patients with VUR and associated urological anomalies have renal scarring. Early recognition and treatment of VUR patients with associated urological anomalies may decrease the risk of renal parenchymal damage.

Vesico-ureteric reflux: using mouse models to understand a common congenital urinary tract defect

Vesico-ureteric reflux (VUR) is a common congenital urinary tract defect in which urine flows retrogradely from the bladder to the kidneys because of an abnormally formed uretero-vesical junction. It is associated with recurrent urinary tract infections, renal hypo/dysplasia, reflux nephropathy, hypertension, and end-stage renal disease. In humans, VUR is genetically and phenotypically heterogeneous, encompassing diverse renal and urinary tract phenotypes. To understand the significance of these phenotypes, we and others have used the mouse as a model organism and this has led to the identification of new candidate genes. Through careful phenotypic analysis of these models, a new understanding of the genetics and biology of VUR is now underway.

Genetics of vesicoureteral reflux

Primary vesicoureteral reflux (VUR) is the most common urological anomaly in children, affecting 1-2% of the pediatric population and 30-40% of children presenting with urinary tract infections (UTIs). Reflux-associated nephropathy is a major cause of childhood hypertension and chronic renal failure. The hereditary and familial nature of VUR is well recognized and several studies have reported that siblings of children with VUR have a higher incidence of reflux than the general pediatric population. Familial clustering of VUR implies that genetic factors have an important role in its pathogenesis, but no single major locus or gene for VUR has yet been identified and most researchers now acknowledge that VUR is genetically heterogeneous. Improvements in genome-scan techniques and continuously increasing knowledge of the genetic basis of VUR should help us to further understand its pathogenesis.

Endoscopic treatment of primary grade V vesicoureteral reflux using hyaluronic acid copolymer (DX/HA)

PURPOSE

Since DX/HA was approved by the Food and Drug Administration in 2001 as an acceptable tissue-augmenting substance for subureteral injection, endoscopic treatment has become increasingly popular for treating vesicoureteral reflux (VUR). However, most paediatric urologists still continue to recommend ureteral reimplantation as the treatment of choice in the management of grade V VUR. The purpose of this study was to prospectively evaluate the effectiveness of endoscopic subureteral injection of DX/HA in the treatment of grade V reflux.

MATERIALS AND METHODS

During 2001-2009, 56 children (35 males, 21 females) with primary grade V VUR underwent endoscopic treatment using DX/HA. Their ages ranged from 4 months to 11 years. Forty-nine patients had unilateral grade V VUR, and seven had bilateral grade V (63 refluxing ureters including 17 duplex systems). Renal scarring on dimercaptosuccinic acid was observed in 39 kidneys (mild scarring 13, moderate scarring 14 and severe scarring 12). In all patients, endoscopic injection was made after inserting the needle within the wide ureteral orifice. Renal ultrasound and voiding cystourethrogram was performed 3 months after the endoscopic treatment. If VUR had not resolved, the patient was considered for further endoscopic treatment. After the VUR was resolved, children were followed with renal ultrasound at 1 year and every 2 years thereafter.

RESULTS

The VUR completely resolved after first injection of DX/HA in 33 (52.4%) ureters and downgraded to grade I VUR in 7 (11.1%) ureters. 19 (30.2%) ureters required a second injection, and 4 (6.3%) ureters required a third injection to resolve VUR. No children in this series needed reimplantation of ureters or presented with ureteral obstruction during follow-up.

CONCLUSION

Endoscopic treatment with DX/HA is effective in eradicating grade V primary reflux. This simple and minimally invasive treatment should be offered to all parents of children with grade V VUR as an alternative to ureteral reimplantation.

DMSA scan for revealing vesicoureteral reflux in young children with urinary tract infection

OBJECTIVES

The objective of this study was to assess the ability of acute dimercaptosuccinic acid (DMSA) scintigraphy for revealing vesicoureteral reflux (VUR) in young children after a first febrile urinary tract infection (UTI).

METHODS

Children aged<or=24 months and were admitted with a first febrile UTI during a 5-year period were evaluated. The ability of acute DMSA scintigraphy to reveal dilating (grades 3-5) or severe (grades 4-5) VUR was assessed by comparing DMSA scan findings with those of voiding cystourethrography.

RESULTS

Of the 296 children included, 46 had dilating and 25 severe VUR. Abnormal DMSA scan results were associated with an odds ratio of 4.36 for dilating and 5.50 for severe VUR. For detecting dilating VUR, the area under the curve (AUC) was 0.68, the positive likelihood ratio (LR) was 2.00, and the negative LR was 0.46; for severe VUR, those values were 0.69, 2.10, and 0.38, respectively. Children with abnormal DMSA scan results combined with abnormal ultrasonography had an odds ratio of 3.60 for dilating and 6.32 for severe VUR. Despite normal findings on both investigations, 12 children had dilating and 4 severe VUR. For dilating VUR, the area under the (AUC) was 0.65, the positive LR was 1.70, and the negative LR was 0.47; for severe VUR, the values were 0.69, 1.90, and 0.29, respectively.

CONCLUSIONS

Our data suggest that acute DMSA scintigraphy has limited overall ability in identifying VUR and should not be endorsed as replacement for voiding cystourethrography in the evaluation of young children with a first febrile UTI.

Antenatal and postnatal ultrasound in the evaluation of the risk of vesicoureteral reflux

Antenatal hydronephrosis (ANH) is a frequent anomaly detected on fetal ultrasound scans. There is no consensus recommendation for the postnatal follow-up and/or the necessity to perform a voiding cystourethrography (VCUG) to diagnose vesicoureteral reflux (VUR). We conducted a cohort/non-randomized trial of 121 patients with ANH, defined as an anterior posterior diameter (APD) >or=5 mm after the 20th week of gestation, to evaluate the ability of the antenatal and postnatal ultrasonography results to predict VUR. All infants had two successive ultrasounds at 5 days and 1 month, respectively, after birth. A VCUG was performed at 6 weeks in children with a persistent APD >or=5 mm and/or an ureteral dilatation observed on at least one of two postnatal ultrasounds. In total, 88 patients had VCUG and nine had VUR, with five having high-grade reflux (>grade II). The risk of VUR increased significantly with the degree of APD detected on the postnatal ultrasound scan (p = 0.03). The odds ratios were 5.0 [95% confidence interval (CI) 0.5-51.2] for APD = 7-9 mm and 9.1 (95% CI 1.0-80.9) for APD >or=10 mm. The results of this study show that among our patient cohort antenatal ultrasound was not predictive of reflux. There was, however, a relation between the importance of the postnatal renal pelvis diameter and the risk of VUR. A cut-off of 7 mm showed a fair ability of ultrasonography to predict VUR and a cut-off of 10 mm enabled all severe refluxes in the 88 patients who had a VCUG to be diagnosed.

Catheter-free methods for vesicoureteric reflux detection: our experience and a critical appraisal of existing data

In recent years, the exact role of vesicoureteric reflux (VUR) in general has become controversial, though in some groups of children the knowledge of the existence or non-existence of VUR is still a very important issue. The number of techniques available for the assessment of VUR is increasing, and a new classification taking into account their real characteristics (direct/indirect, catheter-using/catheter-free, radiation-giving/radiation-free) has been proposed. The purpose of the following review is to evaluate the currently available evidence supporting the use of various catheter-free methods for VUR detection. We believe that as the clinical role of VUR has been questioned, it is even more important for the method of its detection to be user-friendly as regards catheterisation, radiation and availability. There is still no evidence supporting the assertion that any of the catheter-free methods of VUR detection might be the optimal one for any child. However, there are some groups of children who would benefit from using them. New studies using new, catheter-free methods of VUR detection or a combination of two or more of the methods described may prove useful in improving sensitivity and providing additional data on this important issue.

Vesicoureteral reflux associated renal damage: congenital reflux nephropathy and acquired renal scarring

PURPOSE

The pathophysiology, evaluation, description and clinical implications of renal damage associated with vesicoureteral reflux remain controversial. We summarized the current understanding of this important aspect of clinical vesicoureteral reflux.

MATERIALS AND METHODS

We performed a detailed review of the literature on clinical, pathological and experimental data related to congenital vesicoureteral reflux and bladder dynamics. We also reviewed the clinical context and imaging evaluation with underlying experimental data related to post-infectious reflux nephropathy.

RESULTS

Congenital reflux nephropathy is a pattern of impaired renal function and development with renal dysplasia as the most severe but not the only form. Mechanisms of developmental disruption are potentially related to vesicoureteral reflux dynamics during gestation and associated bladder dynamics, which may continue into postnatal life. Acquired renal injury associated with infection is related to particular bacterial and host factors that determine infection virulence, host inflammatory response and tissue recovery. As best seen on dimercapto-succinic acid scan, acute changes may resolve but may also persist as permanent renal scarring. Specific risk factors for acute pyelonephritis and renal scarring in patients with vesicoureteral reflux include higher reflux grade, dysfunctional voiding/elimination, recurrent pyelonephritic episodes and delayed initiation of antibiotic therapy. Low pressure sterile reflux is not a cause of reflux nephropathy.

CONCLUSIONS

Renal damage associated with vesicoureteral reflux may be congenital or acquired and the respective pathophysiological mechanisms are likely different. Congenital damage is often dysplasia, which may be a result of disordered renal development secondary to significant alterations in bladder dynamics. These processes may continue into the newborn period while kidney maturation continues. Recognizing the clinical potential for ongoing effects on renal function and the role of bladder development are important for clinical care. Post-pyelonephritic acquired damage is the result of a complex interaction of host and bacterial factors that leads to acute alterations in renal function, and may lead to permanent renal scarring. Strategies for timely intervention as well as prevention are essential to limit the risk of permanent renal injury, which may predispose to hypertension and renal insufficiency in some patients.

Could prophylactic antibiotics be stopped in patients with history of vesicoureteral reflux?

OBJECTIVE

To compare the incidence and type of urinary tract infection (UTI) in patients with primary vesicoureteral reflux (VUR) diagnosed after a febrile UTI while they were on prophylactic antibiotics (PA) and after stopping PA.

MATERIALS AND METHODS

Criteria to discontinue PA were: no UTI during 12+ or more months on PA, old enough to communicate UTI symptoms, potty trained and absence of risk factors for UTI. Patients with at least 1 year of follow up without PA were included (n=77). We recorded: age at which PA was indicated and stopped, time on and off PA, incidence and type of UTI (cystitis vs acute pyelonephritis (APN)), and renal scan results.

RESULTS

PA was started and stopped at a mean age of 18.5 and 61 months, respectively. Mean time on PA was 39 months (range 12-95): 25 patients had 44 UTI episodes (0.17 episodes/patient/year), and 31 (70%) of them were APN. Mean time of antibiotics was 44.5 months (range 12-162): 13 patients had 24 UTI episodes (0.08 episodes/patient/year), eight (33%) of which were APN (P<0.05). A renal scan was performed in 71 patients after the index infection and repeated in 12. Two patients lost renal function while still on PA.

CONCLUSION

Discontinuing PA in patients with history of VUR is a safe practice and should be considered as a management option.

Sensitivity of ultrasonography in detecting renal parenchymal defects: 6 years' follow-up

While (99m)Tc-dimercaptosuccinic acid (DMSA) scanning is still considered the most accurate method for the assessment of renal parenchymal defects (RPDs), our study 6 years previously suggested that ultrasonography (US) could be a safe and efficient substitute for this purpose, provided that it is reliably performed and that renal function parameters are followed. By comparison of the original and follow-up study data from 67 children, the accuracy of our recommendations was re-evaluated. US was performed and renal function parameters investigated and correlated to the DMSA scans from the original study. US identified all six patients with clinically significant RPD and 52/61 with clinically insignificant RPDs, seen on the DMSA scans. Twenty two out of 22 severe RPDs, 21/23 moderate RPDs and 20/40 mild RPDs seen on the DMSA scans were detected by US. In ten cases normal US findings from the original study were rendered abnormal, correlating well with the DMSA scans with respect to RPD localization and kidney size. These results further support our previous suggestion that US is a safe and harmless alternative to DMSA scanning in the detection and follow-up of RPDs. While it cannot be excluded that small RPDs missed on the initial US might 'develop' clinical significance in later life, children with normal findings on initial US should have another sonogram done, at the shortest a year later, together with an investigation of renal function parameters.

Predictors of renal scar in children with urinary infection and vesicoureteral reflux

We evaluated the predictors of renal scar in children with urinary tract infections (UTIs) having primary vesicoureteral reflux (VUR). Data of patients who were examined by dimercaptosuccinic acid (DMSA) scintigraphy between 1995 and 2005 were evaluated retrospectively. Gender, age, reflux grade, presence/development of scarring, breakthrough UTIs, and resolution of reflux, were recorded. The relation of gender, age and VUR grade to preformed scarring and the relation of gender, age, VUR grade, presence of preformed scarring, number of breakthrough UTIs and reflux resolution to new scarring were assessed. There were 138 patients [male/female (M/F) 53/85]. Multivariate analysis showed that male gender [odds ratio (OR) 2.5], age > or = 27 months in girls (OR 4.2) and grades IV-V reflux (OR 12.4) were independent indicators of renal scarring. On the other hand, only the presence of previous renal scarring was found to be an independent indicator for the development of new renal scar (OR 13.4). In conclusion, while the most predictive variables for the presence of renal scarring among children presenting with a UTI were male gender, age > or = 27 months in girls, and grades IV-V reflux, the best predictor of new scar formation was presence of previous renal scarring.

Magnetic resonance urography in children

Magnetic resonance (MR) urography is a powerful tool that fuses anatomic information with functional data in a single test without the use of ionizing radiation. This article provides an overview of the technical aspects of MR urography and common clinical applications, such as the evaluation of hydronephrosis, reflux nephropathy, and renal dysplasia.

Demography of renal disease in childhood

The demography of renal failure in childhood is examined through an analysis of the UK Renal Registry data on patients in established renal failure (ERF) and studies of chronic kidney disease populations. The predominant cause is renal dysplasia and related conditions. Congenital obstructive uropathy is the third largest group overall and the second in early childhood. Males predominate in both these groups. Antenatal diagnoses are frequently not made despite routine scanning. Those children, who present to nephrology after the age of 3 months without an antenatal diagnosis, progress to ERF later than those diagnosed antenatally. Discrepancies exist between the demography of antenatal diagnoses and those seen postnatally. This is likely to represent the limitations of antenatal ultrasound as a diagnostic screening tool.

Is antibiotic prophylaxis in children with vesicoureteral reflux effective in preventing pyelonephritis and renal scars? A randomized, controlled trial

OBJECTIVES

There has been intense discussion on the effectiveness of continuous antibiotic prophylaxis for children with vesicoureteral reflux, and randomized, controlled trials are still needed to determine the effectiveness of long-term antibiotics for the prevention of acute pyelonephritis. In this multicenter, open-label, randomized, controlled trial, we tested the effectiveness of antibiotic prophylaxis in preventing recurrence of pyelonephritis and avoiding new scars in a sample of children who were younger than 30 months and vesicoureteral reflux.

METHODS

One hundred patients with vesicoureteral reflux (grade II, III, or IV) diagnosed with cystourethrography after a first episode of acute pyelonephritis were randomly assigned to receive antibiotic prophylaxis with sulfamethoxazole/trimethoprim or not for 2 years. The main outcome of the study was the recurrence of pyelonephritis during a follow-up period of 4 years. During follow-up, the patients were evaluated through repeated cystourethrographies, renal ultrasounds, and dimercaptosuccinic acid scans.

RESULTS

The baseline characteristics in the 2 study groups were similar. There were no differences in the risk for having at least 1 pyelonephritis episode between the intervention and control groups. At the end of follow-up, the presence of renal scars was the same in children with and without antibiotic prophylaxis.

CONCLUSIONS

Continuous antibiotic prophylaxis was ineffective in reducing the rate of pyelonephritis recurrence and the incidence of renal damage in children who were younger than 30 months and had vesicoureteral reflux grades II through IV.

Dimercaptosuccinic acid (DMSA) renal scan in the evaluation of hypertension in children

Renal scarring is known to be associated with hypertension. The primary objective of this study was to investigate the prevalence of renal scarring in children referred to our clinic with hypertension. The secondary objective was to compare renal ultrasound (US) examination with dimercaptosuccinic acid (DMSA) renal scan in diagnosing renal scars in these patients. The study included 159 patients who underwent DMSA renal scan as well as renal US for the evaluation of hypertension of unknown etiology. Thirty-three (21%) patients were found to have renal scars; their demographic details, including mean age and gender distribution, were not significantly different from those without renal scars. In comparison with the DMSA renal scan, sensitivity and specificity of renal US in diagnosing renal scars were 36% and 94%, respectively. In our study, in which the prevalence of scarring was 21%, this gave positive predictive and negative predictive values of 63% and 85%, respectively. In conclusion, our study indicates that renal scarring is present in 21% of otherwise healthy children who are evaluated for newly diagnosed hypertension, and renal US is not a sensitive imaging modality to rule out renal scarring.

Evaluation of reflux nephropathy, pyelonephritis and renal dysplasia

MR urography has the potential to significantly improve our understanding of the relationship between reflux nephropathy, pyelonephritis, vesicoureteric reflux and renal dysplasia. MR urography utilizes multiple parameters to assess both renal anatomy and function and provides a more complete characterization of acquired and congenital disease. Pyelonephritis and renal scarring can be distinguished by assessing the parenchymal contours and signal intensity. Characteristic imaging features of renal dysplasia include small size, subcortical cysts, disorganized architecture, decreased and patchy contrast enhancement as well as a dysmorphic pelvicalyceal system. Because of its ability to subdivide and categorize this heterogeneous group of disorders, it seems inevitable that MR urography will replace DMSA renal scintigraphy as the gold standard for assessment of pyelonephritis and renal scarring. MR urography will contribute to our understanding of renal dysplasia and its relationship to reflux nephropathy.

Renal dysplasia and MRI: a clinician's perspective

Renal dysplasia is a common abnormality in children. The role of MRI in evaluating children with renal dysplasia is evolving. More information is clearly necessary before MRI replaces conventional imaging modalities. In order to appropriately use MRI, the radiologist must have an understanding of the clinical questions that are important in the management of children with renal dysplasia. This review provides background information on renal dysplasia for the pediatric radiologist. The focus is on unilateral disease, especially multicystic dysplastic kidneys, and bilateral dysplasia, which is the most common cause of kidney failure in children. The emphasis is on the important clinical issues, and the potential of MRI as a methodology for providing clinically useful information not otherwise available from other imaging modalities.