Nadir creatinine in posterior urethral valves: How high is low enough?

Deep learning imaging features derived from kidney ultrasounds predict chronic kidney disease progression in children with posterior urethral valves

BACKGROUND

We sought to use deep learning to extract anatomic features from postnatal kidney ultrasounds and evaluate their performance in predicting the risk and timing of chronic kidney disease (CKD) progression for boys with posterior urethral valves (PUV). We hypothesized that these features would predict CKD progression better than clinical characteristics such as nadir creatinine alone.

METHODS

We performed a retrospective cohort study of boys with PUV treated at two pediatric health systems from 1990 to 2021. Features of kidneys were extracted from initial postnatal kidney ultrasound images using a deep learning model. Three time-to-event prediction models were built using random survival forests. The Imaging Model included deep learning imaging features, the Clinical Model included clinical data, and the Ensemble Model combined imaging features and clinical data. Separate models were built to include time-dependent clinical data that were available at 6 months, 1 year, 3 years, and 5 years.

RESULTS

Two-hundred and twenty-five patients were included in the analysis. All models performed well with C-indices of 0.7 or greater. The Clinical Model outperformed the Imaging Model at all time points with nadir creatinine driving the performance of the Clinical Model. Combining the 6-month Imaging Model (C-index 0.7; 95% confidence interval [CI] 0.6, 0.79) with the 6-month Clinical Model (C-index 0.79; 95% CI 0.71, 0.86) resulted in a 6-month Ensemble Model that performed better (C-index 0.82; 95% CI 0.77, 0.88) than either model alone.

CONCLUSIONS

Deep learning imaging features extracted from initial postnatal kidney ultrasounds may improve early prediction of CKD progression among children with PUV. A higher resolution version of the Graphical abstract is available as Supplementary information.

Nadir creatinine as a predictor of renal outcomes in PUVs: A systematic review and meta-analysis

Background

Posterior urethral valves (PUVs) represent the most severe pediatric obstructive uropathy, responsible for chronic renal failure in up to 65% of cases and progression to end-stage kidney disease (ESKD) in about 8%-21% of patients. Unfortunately, renal outcomes have poorly improved over time. The key point is to identify patients at risk; thus, several prenatal and postnatal prognostic factors have been analyzed to improve clinical outcomes. Postnatal nadir creatinine seems to accurately predict long-term renal prognosis, but there is no definitive evidence to support this finding.

Objective

We performed a systematic review with meta-analysis to analyze the predictive value of nadir creatinine on long-term renal function in infants with PUVs.

Methods

We conducted this systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed and Cochrane Library were systematically searched for studies published from January 2008 to June 2022. All the articles were checked independently by two reviewers in two steps.

Results

A total of 24 articles were screened, and 13 were included for data extraction. Data from 1,731 patients with PUVs were analyzed, with a mean follow-up of 5.5 years; of these, on average, 37.9% developed chronic kidney disease (CKD) and 13.6% developed ESKD. All the articles evaluated nadir creatinine as a predictor of CKD, most using a level of 1 mg/dL, with statistical significance at the 5% level. The relative risk of developing CKD in patients with creatinine values higher than the nadir cutoff considered was 7.69 (95% CI: 2.35-25.17, I ² = 92.20%, p < 0.001).

Conclusions

Nadir creatinine is the best prognostic factor for long-term renal function in patients affected by PUV. A value above the cutoff of 1 mg/dL should be considered a significant predictor for the risk of CKD and ESKD. Further studies are needed to define different nadir creatinine cutoffs for better stratification of the different CKD stages and for the development of reliable scores, which include the association of several variables.

Role of progressive urethral dilation and primary valve ablation in the long-term renal outcomes of small, preterm infants with posterior urethral valve

INTRODUCTION

PUV patients managed with primary vesicostomy instead of primary valve ablation (PVA) historically are preterm, low-birth-weight (LBW) infants with inadequate urethral size. We previously described progressive urethral dilation (PUD) as an effective method of enhancing the likelihood of PVA in these infants, allowing equal access to PVA as an initial management method.

OBJECTIVE

We aim to characterize renal outcomes in patients managed with PUD + PVA and compare this to outcomes with PVA alone. We also re-examine the effect of LBW and gestational age on renal outcomes in PUV with a cohort treated uniformly by PVA.

METHODS

We performed retrospective review of 78 neonates with PUV treated with PVA prior to 10 weeks of age with >1 year of follow up. Before valve ablation, boys either underwent PUD (serial upsizing of a smaller bore urethral catheter to an 8Fr catheter; PUD + PVA) or non-dilation (smaller bore catheter was maintained; PVA-only). PUD + PVA versus PVA-only was compared using chi-square and t-test. Logistic regression was performed to assess the effect of PUD, preterm (<37 weeks), LBW (<2.5 kg), and other predictors on the final outcomes of CKD3+ and ESRD.

RESULTS

31 of 78 patients underwent PUD + PVA. Mean follow up was 5.2 years (SD 3.4), with no significant difference between PUD + PVA and PVA-only. The PUD + PVA group included significantly lower gestational age infants with lower birth weight and ablation weight. There was no significant effect of PUD on final CKD3+ or ESRD outcome on univariable or multivariable analysis. When adjusted for other variables, only Cr nadir >0.5 remained an independent predictor of CKD3+ (OR 41.2; p < 0.001) and ESRD (OR 18.9; p = 0.015).

DISCUSSION

We previously demonstrated that PUD is an effective means to achieve PVA in small neonates who might otherwise require vesicostomy. The data herein demonstrates no significant effect of PUD on renal outcomes. In this unique cohort of newborns treated with PVA, only creatinine nadir and not gestational age or an independent predictor of outcomes.

CONCLUSION

In small preterm infants who would have been excluded from PVA due to limited urethral size, PUD + PVA confers the same renal outcomes as PVA alone in larger infants. This novel data will assist in the risk-benefit analysis of using PUD before PVA in newborns diagnosed with PUV. When primary intervention is uniformly PVA, preterm birth and LBW are not independent predictors of renal outcomes.

Chronic Kidney Disease in Boys with Posterior Urethral Valves-Pathogenesis, Prognosis and Management

Posterior urethral valves (PUV) are the most common form of lower urinary tract obstructions (LUTO). The valves can be surgically corrected postnatally; however, the impairment of kidney and bladder development is irreversible and has lifelong implications. Chronic kidney disease (CKD) and bladder dysfunction are frequent problems. Approximately 20% of PUV patients will reach end-stage kidney disease (ESKD). The subvesical obstruction in PUV leads to muscular hypertrophy and fibrotic remodelling in the bladder, which both impair its function. Kidney development is disturbed and results in dysplasia, hypoplasia, inflammation and renal fibrosis, which are hallmarks of CKD. The prognoses of PUV patients are based on prenatal and postnatal parameters. Prenatal parameters include signs of renal hypodysplasia in the analysis of fetal urine. Postnatally, the most robust predictor of PUV is the nadir serum creatinine after valve ablation. A value that is below 0.4 mg/dl implies a very low risk for ESKD, whereas a value above 0.85 mg/dl indicates a high risk for ESKD. In addition, bladder dysfunction and renal dysplasia point towards an unbeneficial kidney outcome. Experimental urinary markers such as MCP-1 and TGF-β, as well as microalbuminuria, indicate progression to CKD. Until now, prenatal intervention may improve survival but yields no renal benefit. The management of PUV patients includes control of bladder dysfunction and CKD treatment to slow down progression by controlling hypertension, proteinuria and infections. In kidney transplantation, aggressive bladder management is essential to ensure optimal graft survival.

Catheter test: A reliable alternative to assess adequacy of bladder management in patients of PUV in developing countries

INTRODUCTION

Following posterior urethral valve ablation, persisting bladder dysfunction can lead to lack of improvement or worsening of hydronephrosis and as well, to lack of improvement or even worsening renal function. On the other hand, managing bladder dysfunction offers the possibility of lessening both the degree of hydronephrosis and the level of serum creatinine. As we have no available urodynamics we feel impelled to find other means of diagnosing and managing abnormal bladder dynamics in these boys. We wanted to determine if a short course of continuous bladder drainage would be an effective means of lowering abnormal serum creatinine levels. Based on an assumption that most bladders following valve ablation, especially in those boys with a persistently elevated serum creatinine post valve ablation, have some form of dysfunction, we wanted to determine if a short course of continuous catheter drainage could improve these abnormal serum creatinine levels.

METHODS

The study was conducted over a 3year period and included all children up to 3 years of age who had higher age-appropriate nadir serum creatinine, 3 months post valve ablation. Patients were followed up at 1 week, 2 month and 3-month post valve ablation. On third follow-up visit patients with an elevated serum creatinine level were subjected to continuous bladder drainage (catheter test) for 5 days and serum creatinine level was recorded at the end of 5th day. Enforced bladder management which included dose titration of anti-muscaranic drugs and clean intermittent catheterization (CIC) with or without nocturnal catheter drainage (NOC) was instituted for next 3 months. Serum creatinine was determined at the end of the 3 month period and compared with prior values.

RESULTS

A total of 21 patients were included in the study. The mean age of the children at the time of valve ablation was 6.97 ± 4.38 months. There was a significant fall in serum creatinine from 0.64 ± 0.12 mg/dl pre 5 days of drainage to 0.48 ± 0.10 at the end of the 5 day period (p = 0.024) along with a significant rise in GFR (p = 0.001). Following 3 months of enforced bladder management, there was a very mild rise in creatinine to 0.51, a normal age adjusted value.

DISCUSSION

The study demonstrates the importance of early diagnosis of bladder dysfunction in boys with an elevated serum creatinine levels post valve ablation. Elevated nadir serum creatinine 3 months post ablation seems to be a useful indicator of possible bladder dysfunction; lowering of serum creatinine following a 5 day trial of continuous bladder drainage confirms this diagnosis. However, the lack of availability of urodynamic testing leaves the specific type of bladder dysfunction undiagnosed.

CONCLUSION

Lowering of serum creatinine following a 5-day trial of continuous bladder drainage can be used as a rough indicator of existing bladder dysfunction in boys with a history of PUV and should be used in countries without urodynamic equipment as an indicator for at least a 3 month trial of enforced bladder management.

Nadir creatinine predicts long-term bladder function in boys with posterior urethral valves

INTRODUCTION

Posterior urethral valves (PUV) cause lower urinary tract obstruction leading to increased intravesical pressure during fetal urinary tract development. Though the bladder and kidneys are separate organs, with different embryological origins, they are complementary and influence each other both before and after birth. We aimed to assess the relationship between renal and bladder function in boys with PUV and whether early renal markers could predict future bladder function.

PATIENTS AND METHODS

We included all boys with prenatally suspected lower urinary tract obstruction, born between 2000 and 2013, in two University Hospitals, with at least 5 years follow-up. We excluded patients who presented a Lower Urinary Tract Obstruction other than PUV, children who presented multiple birth defects and neonatal deaths and those with incomplete long-term renal or bladder function data. We included data on nadir creatinine (NC), long-term renal function and long-term bladder function (defined by Uroflow parameters). Boys with PUV were divided into three severity groups for renal function according to their NC and three severity groups for bladder function as determined by Uroflow.

RESULTS

We included 73 boys. Average nadir creatinine was 43.4 ± 26.1 μmol/L. Twenty-nine boys (49.3%) presented a NC < 35 μmol/L, thirty-eight (52.1%) a NC between 35 and 75 μmol/L, and 6 (8.2%) a NC > 75 μmol/L. Thirty-eight (52.1%) presented normal bladder function, 23 (31.5%) presented moderately impaired bladder function and 12 (16.4%) presented severely impaired bladder function. 41.4% of boys with NC < 35 had abnormal bladder function vs 46.2% of those with an NC between 35 and 75 μmol/L and 83.3% of boys with NC > 75 μmol/L. Nadir creatinine both predicted both bladder function and renal status (table 1). Correlation between presence of grade 3-5 CKD and poor uroflow was also significant (p < 0.005).

DISCUSSION

Nadir creatinine was significantly correlated to bladder function at 5 years of age. What this study suggests is that as nadir creatinine increases so does the risk of severe bladder dysfunction. Our results, though limited to flowmeter and renal function, could help pediatric urologist tailor bladder function monitoring, and indicate which patients could benefit from more aggressive bladder therapy.

CONCLUSION

Bladder and renal function are linked in boys with posterior urethral valves. Boys with high nadir creatinine could benefit from early bladder function evaluation and management.

Urinary Tract Dilation in the Fetus and Neonate

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

Predictors of advanced chronic kidney disease in infancy after definitive vesicoamniotic shunting for congenital lower urinary tract obstruction

BACKGROUND

Severe congenital lower urinary tract obstruction (cLUTO) is associated with poor postnatal outcomes, including chronic and end stage kidney disease, and high mortality. Studies of the impact of fetal intervention through vesicoamniotic shunting are marred by a device malfunction rate of up to 60%. In this study, we delineate the postnatal course and infant kidney function following definitive urinary diversion in utero.

MATERIALS AND METHODS

This is a retrospective, single-center cohort study of 16 male infants who survived the fetal intervention to birth, from 2010 to 2014 at a single center. All had patent shunts in place at birth. Perinatal and biochemical characteristics were collected with patients followed for one year, or until demise, with serial measures of serum creatinine (SCr) and serum cystatin C (CysC).

RESULTS

Of the 16 males, 81% were non-white (38% black, 43% Hispanic). Shunts were placed at a median of 20 weeks (IQR 19,23) gestation, with median fetal bladder volume of 39 cm³ (IQR 9.9,65). All neonates were born preterm [median 34 weeks (IQR 31,35)] and the majority with low birth weight [median 2340 grams (1,895, 2,600)]. 63% required positive pressure ventilation. Advanced chronic kidney disease stage 4-5 at 1 year of age was predicted by neonatal characteristics: peak SCr ≥2 mg/dl, time to peak SCr > 6 days, discharge SCr ≥1.0 mg/dl, CysC ≥2.5 mg/l, urine protein:creatinine ≥4.8 mg/mg, urine microalbumin:creatinine ≥2.2 mg/mg. In infancy, a nadir SCr ≥0.5 mg/dl occurring before 160 days (5.3 months) of age was also predictive of advanced chronic kidney disease stage 4-5 at 1 year. Three patients died in the neonatal period, with 1 receiving kidney replacement therapy (KRT). Three additional patients required KRT before 12 months of age.

CONCLUSIONS

Even with definitive vesicoamniotic shunting for cLUTO, postnatal morbidity and mortality remain high, emphasizing the role of renal dysplasia, in spite of urinary diversion, in postnatal kidney dysfunction. Neonatal and infant biochemical parameters exhibit distinct trends that offer families and physicians a better understanding of the prognosis of childhood kidney function.

Posterior urethral valves: Role of prenatal diagnosis and long-term management of bladder function; a single center point of view and review of literature

Posterior Urethral Valves (PUV) are the most common cause of lower urinary tract obstruction. More severe forms are detected early in pregnancy (mainly type I), while other forms are usually discovered later in childhood when investigating lower urinary tract symptoms. Bladder dysfunction is common and is associated with urinary incontinence in about 55% (0%-72%). Despite the removal of the obstruction by urethral valve ablation, pathological changes of the urinary tract can occur with progressive bladder dysfunction, which can cause deterioration of the upper urinary tract as well. For this reason, all children with PUV require long-term follow-up, always until puberty, and in many cases life-long. Therefore, management of PUV is not only limited to obstruction relief, but prevention and treatment of bladder dysfunction, based on urodynamic observations, is paramount. During time, urodynamic patterns may change from detrusor overactivity to decreased compliance/small capacity bladder, to myogenic failure (valve bladder). In the past, an aggressive surgical approach was performed in all patients, and valve resection was considered an emergency procedure. With the development of fetal surgery, vesico-amniotic shunting has been performed as well. Due to improvements of prenatal ultrasound, the presence of PUV is usually already suspected during pregnancy, and subsequent treatment should be performed in high-volume centers, with a multidisciplinary, more conservative approach. This is considered to be more effective and safer. Primary valve ablation is performed after clinical stability and is no longer considered an emergency procedure after birth. During childhood, a multidisciplinary approach (pediatric urologist, nephrologist, urotherapist) is recommended as well in all patients, to improve toilet training, using an advanced urotherapy program with medical treatments and urodynamic evaluations. The aim of this paper is to present our single center experience over 30 years.

Evaluating the impact of pop-off mechanisms in boys with posterior urethral valves

INTRODUCTION

Posterior urethral valves are urethral leaflets that cause Lower Urinary Tract Obstruction (LUTO) in boys and are associated with congenital renal dysplasia and abnormal bladder function. They affect 1:4,000 to 1:25,000 births and can be responsible for End-Stage Renal Failure in childhood. There have been several studies on the effect of pop-off mechanisms in boys with posterior urethral valves, but results are contradictory. We aimed to assess and discuss the effect of pop-off mechanisms on renal function in a large cohort of patients.

PATIENTS AND METHOD

Boys with PUV with and without pop-off mechanisms (urinoma, VURD or giant bladder diverticula) were divided into three severity groups for renal function according to their nadir creatinine (low-risk NC < 35 μmol/L, intermediate-risk NC between 35 and 75 μmol/L, and high-risk NC > 75 μmol/L). We compared children with and children without pop-off mechanisms for mean renal function as well as patient distribution within each severity group.

RESULTS

We included 137 boys of which 39 had a pop-off mechanism. Patients had complete data for at least 5 years follow-up. Though there was no significant statistical difference in mean renal function between the pop-off and non-pop-off group, patient distribution within each severity group varied according to whether patients had a pop-off mechanism or not.

CONCLUSION

Though there was no significant difference in mean renal function between boys with and without pop-off mechanisms, it is possible that these are two different patient populations and direct comparison is not possible.

Impact of surgical intervention on progression to end-stage renal disease in patients with posterior urethral valve

Background

Posterior urethral valve patients present with varied presentations at any age of life and have significant associated morbidity and require long-term follow-up and care.

Methods

This was a single-center ambispective cohort study carried out over a period of 2 years. Patient data regarding the symptoms, investigations, interventions, secondary complications were recorded and were followed up regularly during the study till either normalization of their creatinine level which was maintained up to one-year post-fulguration (non-CKD) or progression to end-stage renal disease (ESRD) requiring renal transplant. Various clinical factors were then compared between these groups.

Results

The age of presentation varies from 6 months antenatal period to a maximum of 34 years. Most common symptom was of lower urinary tract obstruction, followed by recurrent febrile UTI. The interval between disease presentation detection and PU valve fulguration ranged from 6 days to more than 5 years, median duration being 1 month. 85.7% patients had hydroureteronephrosis on initial USG. In VCUG, there was no significant difference found between the presence of reflux and poor renal outcome. Age of presentation greater than 2 years was seen in 52% of patients with CKD compared to only 10% patients in non-CKD group (significant, p value 0.02). Among patients who developed CKD, 60% of patients had PU valve fulguration after one month of disease presentation, while in contrast, among the non-CKD group, 80% of patients had it done within one month of disease presentation. (significant, p value 0.03).

Conclusions

Late age of presentation, delayed fulguration with high initial creatinine, and failure of serum creatinine to return to normal after one-month post-fulguration are important risk factors in the progression of the disease to ESRD. Symptomatic improvement after interventions does not correlate with progression to ESRD. The number of interventions also does not predict progression to ESRD. Interventions should be chosen wisely on case to restore near-normal physiology and delay progression to ESRD.

Clinical predictors of chronic kidney disease in congenital lower urinary tract obstruction

Congenital lower urinary tract obstruction is associated with oligohydramnios and significant perinatal mortality and long-term chronic kidney disease. The counseling of families facing this diagnosis, especially when prenatal intervention is proposed, is fraught with ambiguity. This review aims to equip the provider with the current evidence behind the conventional and novel biomarkers predictive of chronic kidney disease. The relevant clinical predictors are categorized by when they are identified, antenatally or postnatally, and as either anatomic or chemical. They are considered for their prognostic value and the challenges in obtaining them, specifically the risk to the fetus in the case of prenatal biomarkers. Serum creatinine in infancy is the traditional chemical biomarker of kidney function and continues to be a consistent predictor of future serum creatinine. β-2 microglobulin may provide earlier information regarding fetal glomerular and tubular function and is also predictive of long-term serum creatinine. Renal parenchymal area is an anatomic surrogate of nephron mass that is used in both prenatal and postnatal settings. Understanding the anatomic and chemical biomarkers is essential for future refinement of the staging algorithm used to distinguish which patients may benefit from early in utero intervention.

Serum creatinine levels in cases of posterior urethral valve: 29 years experience of a pediatric urology reference center

OBJECTIVES

The aim of this retrospective study is to describe the importance of serum creatinine levels for the long-term renal outcome in cases of posterior urethral valve.

METHODS

Records of 94 patients who underwent cystoscopic valve ablation were evaluated retrospectively. Demographic variables, radiologic findings, and serum creatinine levels were recorded. Patients were grouped according to the serum creatinine levels in the first month of life. Twenty-four patients' serum creatinine levels were found to be above 1 mg/dL in group 1 and ≤1 mg/dL in 70 patients in group 2.

RESULTS

The initial findings of 74 patients were as follows: pyelonephritis in 24 (32.43%) patients, hydronephrosis in 20 (27.02%), and inability to urinate in 18 (24.32%). Prenatal hydronephrosis was present in 36 cases (38.29%). Of the 92 voiding cystograms, 53.26% had findings that included vesicoureteral reflux. The mean serum creatinine levels of the patients in group 1 increased above 1 mg/dL in the 2nd year, the significant difference between the two groups lasted up to 7 years of age, and no significant difference was observed at the age of 7. The mean serum creatinine levels of the patients in group 2 were observed to increase above 1 mg/dL by the 10th year.

CONCLUSIONS

In patients with posterior urethral valves, nadir creatinine, especially higher than 1 mg/dL, should be considered as high risk for end-stage renal disease. Therefore, clinicians should improve awareness about early detection and treatment of posterior urethral valves, and these patients should be monitored as early as possible for the risk of chronic kidney disease.

Renal outcomes of neonates with early presentation of posterior urethral valves: a 10-year single center experience

OBJECTIVE

Evaluate renal outcomes and early predictive factors in infants with congenital posterior urethral valves who required catheter or surgical urinary tract decompression within the first 7 days of life.

STUDY DESIGN

A 10-year retrospective study at a single hospital. Primary outcomes were estimated glomerular filtration rate (eGFR) and development of end stage renal disease (ESRD).

RESULTS

Of 35 infants, 50% developed eGFR <90 mL/min/1.73 m² and 15% progressed to ESRD. Nadir creatinine, need for invasive ventilation in the newborn period, and need for surgical diversion after catheter diversion were associated with worse outcomes. 50% of infants requiring invasive ventilation as neonates developed eGFR <60 mL/min/1.73 m² in childhood.

CONCLUSIONS

Half of infants with early presentation and intervention developed significant renal insufficiency in childhood, similar to children with later presentation or who had fetal intervention. Invasive ventilation in the newborn period and need for surgical urinary diversion are associated with worse outcomes.

Prediction model of postnatal renal function in fetuses with lower urinary tract obstruction (LUTO)-Development and internal validation

OBJECTIVE

To develop a prediction model of postnatal renal function in fetuses with lower urinary tract obstruction (LUTO) based on fetal ultrasound parameters and amniotic fluid volume.

METHODS

Retrospective nationwide cohort study of fetuses with postnatally confirmed LUTO and known eGFR. Fetuses treated with fetal interventions such as vesico-amniotic shunting or cystoscopy were excluded. Logistic regression analysis was used to identify prognostic ultrasound variables with respect to renal outcome following multiple imputation of missing data. On the basis of these fetal renal parameters and amniotic fluid volume, a model was developed to predict postnatal renal function in fetuses with LUTO. The main study outcome was an eGFR less than 60 mL/min * 1.73 m² based on the creatinine nadir during the first year following diagnosis. Model performance was evaluated by receiver operator characteristic (ROC) curve analysis, calibration plots, and bootstrapping.

RESULTS

Hundred one fetuses with a confirmed diagnosis of LUTO were included, eGFR less than 60 was observed in 40 (39.6%) of them. Variables predicting an eGFR less than 60 mL/min * 1.73m² included the following sonographic parameters: hyperechogenicity of the renal cortex and abnormal amniotic fluid volume. The model showed fair discrimination, with an area under the ROC curve of 0.70 (95% confidence interval, 0.59-0.81, 0.66 after bootstrapping) and was overall well-calibrated.

CONCLUSION

This study shows that a prediction model incorporating ultrasound parameters such as cortical appearance and abnormal amniotic fluid volume can fairly discriminate an eGFR above or below 60 mL/min * 1.73m² . This clinical information can be used in identifying fetuses eligible for prenatal interventions and improve counseling of parents.

Posterior urethral valve and anterior rectal duplication: a new combination

We present a rare case of association of anterior rectal duplication and posterior urethral valve (PUV). A term neonate with no antenatal concerns was admitted with urosepsis and acute renal injury at 18 days of age. History revealed a poor urinary stream and dribbling. After resuscitation and stabilisation, renal tract ultrasound and micturating cysto-urethrogram were performed. Cystourethroscopy showed PUV and a mass indenting the bladder posteriorly. MRI confirmed the presence of a cystic lesion anterior to the rectum suspicious of rectal duplication. Laparoscopic-assisted excision of the anterior rectal duplication cyst was then performed. The infant recovered uneventfully. Creatinine normalised postoperatively and has been stable at follow-up.

Prenatal extravasation of urine seems to preserve renal function in boys with posterior urethral valves

INTRODUCTION

A posterior urethral valve (PUV) may lead to extravasation of urine, resulting in prenatal ascites and/or perirenal urinoma. Extravasation has been presumed to act as a pop-off mechanism, preserving renal function, but previous reports addressing this presumption have been inconclusive.

AIM OF STUDY

The present study compares renal function in patients with PUV with and without extravasation.

MATERIAL AND METHODS

Sixty boys with a confirmed diagnosis of PUV as neonates (gestational age [GA]<44 weeks) throughout 2001-2016 were included. Clinical data were collected from medical records. Renal function was assessed by nadir plasma creatinine, creatinine at the last follow-up, and glomerular filtration rate (GFR) at the last follow-up. The GFR was estimated using the Schwartz formula. Renal function was classified according to the kidney disease: improving global outcomes (KDIGO) guidelines' grades of chronic kidney disease (CKD). Glomerular filtration rate > 90 ml/min/1.73m² at the last follow-up was classified as normal renal function.

RESULTS

Twelve patients (20%) had ascites and/or urinoma, and 48 (80%) did not. GA and birth weight were not different in patients with and without extravasation. PUV was suspected from prenatal ultrasound findings in 66.7% of the patients in both groups. Median nadir creatinine was 21 (range, 11-33) μmol/L in boys with ascites/urinoma, and all values were within the age-adjusted reference values. Nadir creatinine was 23 (14-199) μmol/L in boys without extravasation, and it was above the normal range in 14 boys. The incidence of elevated nadir creatinine was significantly different in the two groups (p < 0.025). One of the 12 patients with extravasation developed chronic renal failure (CKD 3). In the group of 48 patients without extravasation, 20 (42%) had chronic renal failure grade 2-5, and among these, 5 patients have had a renal transplant (CKD grade 5). The prevalence of CKD grade 2-5 was statistically different in the two groups (p = 0.03). These findings are presented in the summary figure.

CONCLUSION

Extravasation of urine was found in 12 of 60 (20%) boys with PUV. These patients had significantly lower prevalence of CKD at the last follow-up than patients without extravasation. This finding is important in prenatal counseling. It also indicates that prenatal decompression of the bladder and upper tract is beneficial in patients with PUV, which is relevant to the discussion of prenatal intervention in these fetuses.

Outcome of posterior urethral valve in 64 children: a single center's 22-year experience

BACKGROUND

Posterior urethral valve (PUV) is the most serious form of congenital anomalies of kidney and urinary tract (CAKUT) in boys with significant risk of progression to chronic kidney disease (CKD). We present our long-term results in children with PUV.

METHODS

Retrospective chart review of 113 children with PUV followed within the years of 1996-2018 was performed. Clinical, laboratory and epidemiologic parameters were analyzed for their impact on renal outcome.

RESULTS

The median age of diagnosis was 1.00 month (1.00-132.00) and the median follow-up period was 70 months (60.00-216.00). Antenatal diagnosis was present in 33 patients (51.5%) mainly with bilateral hydronephrosis and oligohydramnios. The most common postnatal presentation was recurrent urinary tract infection (UTI) in 14 cases (21.9%) and incontinence in three cases (4.7%). Vesicoureteral-reflux (VUR) was present in 31 cases (48.4%). All patients had surgery and urinary diversion was needed in 18 (28.2%). Varying stages of chronic kidney disease (CKD) developed in 23 cases (35.9%) and rise in serum creatinine was especially prominent after the 4th year of follow-up. Of 23 CKD patients, seven (10.9%) were in ESRD and on dialysis. Mortality occurred in one (1.5%) patient. Hypertension, proteinuria and high initial serum creatinine (>1.28 mg/dL) were statistically significant risk factors for CKD, as expected. Surprisingly VUR and UTI did not show such a significant impact on CKD development. Antenatal detection was with significantly less risk for CKD.

CONCLUSIONS

Our results confirm that PUV has a considerable risk for CKD development. Antenatal diagnosis, management of proteinuria and hypertension may modify this progression. But already injured kidneys still have a potential risk. The need for further research to evaluate the impact of any intervention on long term renal outcome is obvious.

The postnatal management of boys in a national cohort of bladder outlet obstruction

AIM

The most common cause of congenital bladder outlet obstruction (BOO) is posterior urethral valves (PUV). Initial treatment requires decompression, but transurethral incision (TUI) or primary diversion is all described. There is no randomized control trial to guide management. This study aims to describe management, circumcision, and UTI rate in a national cohort of PUV boys.

METHODS

Boys diagnosed with BOO were recruited (via BAPS CASS) over 1 year with ethics committee approval (ref: 12/SC/0416). Data were collected via questionnaire, presented as number (%), analyzed by Mann-Whitney/chi-square/Fisher Exact tests, and p < 0.05 was taken as significant.

RESULTS

BOO presented in 121 boys during 2014-2015, and 113 were PUV. Catheter placement in 87/121(72%) was more likely to happen in antenatal vs. postnatal vs. late(>1 y) presentations, p < 0.0001. Polyuria occurred in 23/45(51%), 12/48(25%), 0/28(0%), respectively, p < 0.0001. Initial surgical treatment was TUI in 108/121(89%) and vesicostomy in 2. Two ureterostomies were secondary procedures. Circumcision was performed in 52/121(43%) in antenatal presentation vs. postnatal vs. late 27/45(60%), 20/48(42%), 2/28(7%), respectively, p = 0.01. 69 UTIs occurred in 49 patients. Circumcision was associated with an 86% reduced risk of UTI, p < 0.0001. There was a 66% reduction in UTI risk associated with TUI alone, p < 0.01. There was 1 death due to pulmonary hypoplasia and renal failure, and 2 experienced end-stage renal failure (ESRF).

CONCLUSION

Standard treatment for BOO and PUV in the current UK cohort is urethral catheterization followed by TUI. Supravesical diversion is a rescue therapy. UTIs are common and reduced by circumcision, with 43% being circumcised. Initial mortality rate was 1%, and 1.6% present in ESRF.

LEVEL OF EVIDENCE

Prognostic study - Level I - Prospective National Cohort Study.

Current strategies to predict and manage sequelae of posterior urethral valves in children

Posterior urethral valves (PUV) constitute a significant urological cause of chronic kidney disease (CKD) in children. The condition is characterised by the unique pathophysiology of the evolution of bladder dysfunction after relief of obstruction, which contributes to CKD. Improvements in prenatal diagnosis followed by selective foetal intervention have not yet produced improvement in long-term renal outcomes, although better patient selection may alter this in the future. Proactive management with surveillance, pharmacotherapy, timed voiding, double voiding, and/or assisted bladder-emptying, is being increasingly offered to those with severe bladder dysfunction and has the potential of reducing the burden of renal disease. Clinicians are currently able to counsel regarding the prognosis using serum creatinine and other emerging markers. However, much of this work remains to be validated. Satisfactory graft survival rates are now reported with aggressive management of bladder dysfunction in children who are candidates for renal transplantation. Knowledge gaps exist in identifying early markers of renal injury, risk stratification, and in understanding patient and carer perspectives in PUV.

Predicting and Modifying Risk for Development of Renal Failure in Boys with Posterior Urethral Valves

PURPOSE OF REVIEW

The purpose of this review is to bring the reader up to date on the current risk factors for the development of renal deterioration in the boys with posterior urethral valves (PUV) and approaches to modify this risk.

RECENT FINDINGS

Renal bladder ultrasound (RBUS) is routinely performed in boys with PUV and recent advancements allow imaging processing that can more accurately quantify renal parenchyma and correlate this with risk for renal loss. Refinement of urine studies may improve our ability to stratify patients into renal loss categories. Use of videourodynamics (VUDS) allows refined assessment of the valve bladder to identify those who might benefit from secondary procedures and/or the addition of targeted pharmacotherapy to improve bladder emptying or dangerous storage pressures. All boys with a history of PUV are at a significant long-term risk of renal deterioration. The literature suggests that several technical advances have improved our ability to predict this risk, although there needs to be further refinement and validation before widespread use. Utilization of close follow-up, VUDS, pharmacotherapy, and bladder drainage provide the best methods to improve care to this group of patients and if more studies confirm their utility, adoption of these as part of standard of care protocols may be warranted.

Prediction of need for intervention in posterior urethral valves: Use of urine osmolality

AIM

Renal tubular dysfunction (RTD) causing obligate production of hypoosmolar urine in boys with posterior urethral valves (PUVs) has been described. It is not known how clinically significant this is. We hypothesize that a feedback loop is present in many PUV boys who suffer deterioration of their lower urinary tract (LUT). RTD results in hypoosmolar urine, obligate polyuria, and bladder stretch-injury. The increasing back-pressure worsens RTD, thus exacerbating the injury. Coexisting renal dysplasia and acquired renal scarring exacerbate this. We compared the concentrating ability (random clinic urine osmolality) of PUV boys who had no LUT deterioration to those who required intervention, examining the confounding effect of renal impairment with a subgroup analysis comparing those with plasma creatinine ≤80μmol/l.

METHODS

A retrospective review of our PUV database was performed. Age, intervention, and highest recorded random clinic urine osmolality (>1year) with concurrent plasma creatinine were recorded (normal urine osmolality 500-850 mOsm/kg). Data are given as median values, analyzed by Mann-Whitney u-test, with P<0.05 deemed significant.

MAIN RESULTS

Urine osmolality was available in 77 boys with PUV out of 125 in our series. Of these, 34 required subsequent intervention (e.g., Mitrofanoff procedure, bladder augmentation). Age at testing trended towards being higher in the intervention group [7.9 (4.3-10.9) years vs. nonintervention 6.3 (4-8.4); P=0.06]. Urine osmolality was significantly reduced in the intervention group [411(293-547) vs. 631 (441-805) mOsm/kg; P<0.001]. Subgroup analysis comparing only those with creatinine ≤80μmol/l was respectively 451 (322-567) mOsm/kg (n=22) vs. 645 (469-810) mOsm/kg (n=40), P<0.01.

CONCLUSION

This study confirms that hypoosmolar urine is highly associated with progression of LUT dysfunction, requiring intervention. Even boys with normal creatinine values have a greater risk of LUT deterioration if they have a RTD and produce hypoosmolar urine.

LEVEL OF EVIDENCE

IV (retrospective service development project).

Can quantity of amniotic fluid reliably predict postnatal renal function in boys with posterior urethral valves: a decision curve analysis

OBJECTIVE

Prenatal management of male fetuses with suspected posterior urethral valves depends on reliable markers for postnatal long-term renal function. Whether ultrasound parameters, including the presence or absence of oligohydramnios, are reliable remains the subject of debate. We decided to evaluate the reliability of quantity of amniotic fluid to predict postnatal renal function using decision curve analysis (DCA), a method for evaluating the clinical utility of a diagnostic test.

METHODS

We analyzed retrospectively 51 male fetuses born with prenatally suspected posterior urethral valves between 2009 and 2012. We studied the relationship between quantity of amniotic fluid on prenatal ultrasound and the nadir creatinine during the first year of life as a proxy of postnatal renal function using DCA.

RESULTS

Twelve fetuses presented with prenatal oligohydramnios. Thirty-one children had a normal nadir creatinine, of which one had prenatal oligohydramnios (3.2%). Thirteen had a nadir creatinine between 35 and 75 μmol/L, of which four had prenatal oligohydramnios (30.8%). Seven had a nadir creatinine >75 μmol/L, all of them had prenatal oligohydramnios.

CONCLUSION

In this retrospective study, DCA confirms the relationship between prenatal quantity of amniotic fluid volume and postnatal renal function. © 2017 John Wiley & Sons, Ltd.

Posterior urethral valves: are neonatal imaging findings predictive of renal function during early childhood?

BACKGROUND

Obstructive renal dysplasia as observed on US is associated with posterior urethral valves and is regarded as predicting poor renal functional outcome.

OBJECTIVE

To investigate whether any characteristic of urinary tract imaging at birth is predictive of renal function in children with prenatally diagnosed posterior urethral valves.

MATERIALS AND METHODS

We reviewed clinical data including renal function (at birth and up to 3 years of age) and clinical outcome (urinary infection, dialysis, renal transplantation). Imaging data included US (dilatation of the urinary tract, renal cortical echogenicity, signs of cystic dysplasia, urinoma) and cystourethrography findings (vesicoureteral reflux, bladder anomalies, presence of valves) from imaging performed directly after birth.

RESULTS

We retrospectively studied 30 children. Three of the 30 (10%) were in renal failure by the age of 3 years. Twelve of 14 (85%) children with parenchymal anomalies (cortical hyperechogenicity or cystic changes) and 8/9 (89%) children with bilateral high-grade reflux had normal renal function at age 3 years. One child without cystic dysplasia or reflux had abnormal renal function from birth. None of the six children with urinoma developed renal failure by the age of 3 years.

CONCLUSION

Presence of cortical hyperechogenicity, cystic changes or bilateral reflux cannot be considered prognostic of renal failure by the age of 3 years.

DNA copy number variants: A potentially useful predictor of early onset renal failure in boys with posterior urethral valves

INTRODUCTION

Posterior urethral valves (PUV) are among the most common urological causes of chronic kidney disease (CKD) in childhood. Recently, genomic imbalances have been cited as potential risk factors for altered kidney function and have been associated with CKD. The phenotypic effects of a copy number variant (CNV) in boys with PUV are unknown. Here, it was hypothesised that the progression to early renal failure in PUV patients may be influenced by genetic aberrations.

OBJECTIVE

To assess the relationship between CNVs and renal outcomes.

PATIENTS AND METHODS

Between September 2012 and July 2015, 45 children with PUV were recruited to evaluate the presence of CNVs in their DNA. The patients' medical records were retrospectively reviewed. The criteria for outcomes of renal function included: assessments of the nadir serum creatinine in the first year of life, the estimated glomerular filtration rate at 1 and 5 years, and the requirement for renal replacement.

RESULTS

Thirteen CNVs were identified in 12 boys (29% of the cohort). Microarray analysis revealed two pathogenic CNVs (well-established CNVs known to be associated with genetic disease) and 11 of unknown significance (CNVs with insufficient current available evidence for unequivocal determination of clinical significance), including genes that have been previously implicated in kidney diseases and urogenital disorders. The median follow-up was 10.2 years (range 3-17.5) in the group of patients with CNV compared with 5.8 years (range 1-16.6) in those CNV-. The nadir creatinine values were significantly higher in boys with CNVs than in those without CNVs (57.5 μmol/L (range 23-215) and 28 μmol/L (range 18-155), respectively (P = 0.05) (Figure). Boys CNV+ had a worse prognosis, with a higher incidence of Stage-V CKD compared with the control group (33% with CNVs vs. 9% in CNV-, P = 0.06) at a median age of 22 months (range 8 months-16 years). Four (33%) patients CNV+ underwent renal transplantation.

DISCUSSION

The role of CNVs in the deterioration of renal function remains unknown. It can be hypothesised that CNVs could be a contributing factor or may serve as an accelerant for the progression to renal failure.

CONCLUSION

The CNVs >100 Kb were significantly associated with early onset renal failure in children with PUV. Prenatal detection of CNV could help to identify foetuses at high risk of severe renal impairment in cases of suspected PUV, especially in cases without oligohydramnios or severe pulmonary hypoplasia. These preliminary results should be confirmed in a larger cohort of patients.