Congenital lower urinary tract obstruction: a population-based epidemiological study

Ultrasound Diagnosis of Malformations of the Fetal Kidneys and Urinary System

Malformations of the fetal kidneys and urinary system are common and easily visualized and diagnosed on ultrasound. This article presents the typical sonographic findings of these abnormalities during the various stages of pregnancy. Because malformations of the urogenital tract often have an association with genetic diseases/ciliopathies, these are also discussed. To complete the article, we provide a brief overview of the normal anatomy of the kidneys and urinary system. The normal anatomy and malformations of the genitalia will not be discussed in this article due to their complexity.

A Neonatal Case of Lower Urinary Tract Obstruction and Imperforate Anus: Urethral Decompression Due to Rectourinary Fistula

Lower urinary tract obstruction (LUTO) is a rare fetal condition associated with significant perinatal morbidity and mortality. Herein, we report a neonatal case of LUTO with anal atresia complicated by anhydramnios and pulmonary hypoplasia. After treatment for severe postnatal respiratory distress, the neonate underwent vesicostomy and colostomy. Postoperatively, respiratory status and renal function improved. This case highlights a unique feature where a large rectovesical fistula channeled fetal urine into the colon, which minimized obstructive damage to the urinary tract and preserved renal morphology. Fetal colonic dilatation and numerous enteroliths indicate urine influx into the intestinal tract. Our case suggests the importance of recognizing such exceptions in complete LUTO to predict postnatal outcomes diagnosed in utero.

Familial congenital lower urinary tract obstruction (LUTO) suggested by screening for lower urinary tract dysfunction in parents of patients: A descriptive study

Background

Congenital lower urinary tract obstruction (LUTO) describes a heterogeneous group of congenital malformations. Posterior urethral valves (PUV) represent the most common entity. Familial occurrence has been described, suggestive of underlying genetic factors. LUTO can occur in various degrees of severity. In severe forms, oligohydramnios, pulmonary hypoplasia, and renal damage can occur resulting in high pre- and postnatal mortality. On the contrary, mild forms may become apparent through recurrent urinary tract infections. Such high phenotypic variability has been described even within the same family. Here, we systematically screened parents of affected children for symptoms of LUTO.

Methods

The study population consisted of parents of LUTO patients. Fathers over 50 years of age were excluded, to avoid inclusion of male phenocopies due to early prostatic hypertrophy. Uroflowmetry, ultrasonography for residual urine and hydronephrosis, and laboratory examination of standard renal retention parameters were assessed, and a detailed patient history was taken, including the assessment of the International Prostate Symptom Score.

Results

Twenty-nine of 42 LUTO families enrolled were found eligible for the present study. Of these, we identified five families in which the father had already been diagnosed with infravesical obstruction (17%). Of the remaining families, nine agreed to participate in our study. Of these nine families, eight families had a child affected with PUV and one family had a child with urethral stenosis. Here, we found two fathers and one mother with symptoms of LUTO suggestive of mild LUTO and one family, in which the unborn male fetal brother of the affected index patient was also diagnosed prenatally with LUTO.

Conclusion

Our observations suggest that LUTOs have a higher heritability than previously thought and that first-degree relatives of the affected should be clinically assessed for symptoms of LUTO.

Post-obstructive diuresis after posterior urethral valve treatment in neonates: a retrospective cohort study

BACKGROUND

The management of posterior urethral valve (PUV) in neonates requires close monitoring in the intensive care unit because of the risk of post-obstructive diuresis (POD). Our aim was to describe the incidence and factors associated with POD in newborns treated for PUV.

METHODS

Retrospective analysis of the medical records of all neonates who underwent surgical intervention for PUV in our neonatal intensive care unit between January 2014 and April 2021.

RESULTS

Of the 40 patients included, 15 (37.5%) had POD defined by urine output > 6 ml.kg-1.h-1 during the first 24 h following urinary tract obstruction relief. At prenatal ultrasound examinations, oligohydramnios was more common in the group with POD than in the group without (53.3% vs. 8%, p = 0.002). Preterm birth was more frequent in neonates with POD (66.7% vs. 8%; p < 0.001). Median serum creatinine (212 [137-246] vs. 95 [77-125] µmol.l-1; p < 0.001) and urea (8.5 [5.2-12.2] vs. 4.1 [3.5-4.7] mmol.l-1; p < 0.001) concentrations on the day of obstruction relief were significantly higher in the group with POD than in the group without. After adjustment for prematurity, logistic regression models confirmed correlation between the occurrence of POD and the severity of the consequences of urethral obstruction (i.e., oligohydramnios and serum creatinine levels; ß = 2.90 [0.88; 5.36], p = 0.013 and ß = 0.014 [0.003; 0.031], p = 0.034, respectively).

CONCLUSIONS

In neonates, POD is common after the relief of PUV-related obstruction. Our findings may help to identify patients at highest risk. A higher resolution version of the Graphical abstract is available as Supplementary information.

Trends in Management of Fetuses with Suspected Lower Urinary Tract Obstruction (LUTO): A High-Risk Fetal and Pediatric Center Experience in a Universal-Access-to-Care System

INTRODUCTION

 Neonates with lower urinary tract obstruction (LUTO) experience high morbidity and mortality associated with the development of chronic kidney disease. The prenatal detection rate for LUTO is less than 50%, with late or missed diagnosis leading to delayed management and long-term sequelae in the remainder. We aimed to explore the trends in prenatal detection and management at a high-risk fetal center and determine if similar trends of postnatal presentations were noted for the same period.

METHODS

 Prenatal and postnatal LUTO databases from a tertiary fetal center and its associated pediatric center between 2009 and 2021 were reviewed, capturing maternal age, gestational age (GA) at diagnosis, and rates of termination of pregnancy (TOP). Time series analysis using autocorrelation was performed to investigate time trend changes for prenatally suspected and postnatally confirmed LUTO cases.

RESULTS

 A total of 161 fetuses with prenatally suspected LUTO were identified, including 78 terminations. No significant time trend was found when evaluating the correlation between time periods, prenatal suspicion, and postnatal confirmation of LUTO cases (Durbin-Watson [DW] = 1.99, p = 0.3641 and DW = 2.86, p = 0.9113, respectively). GA at referral was 20.0 weeks (interquartile range [IQR] 12, 35) and 22.0 weeks (IQR 13, 37) for TOP and continued pregnancies (p < 0.0001). GA at initial ultrasound was earlier in terminated fetuses compared to continued (20.0 [IQR 12, 35] weeks vs. 22.5 [IQR 13, 39] weeks, p < 0.0001). While prenatal LUTO suspicion remained consistently higher than postnatal presentations, the rates of postnatal presentations and terminations remained stable during the study years (p = 0.7913 and 0.2338), as were GA at TOP and maternal age at diagnosis (p = 0.1710 and 0.1921).

CONCLUSION

 This study demonstrated that more severe cases of LUTO are referred earlier and are more likely to undergo TOP. No significant trend was detected between time and prenatally suspected or postnatally confirmed LUTO, highlighting the need for further studies to better delineate factors that can increase prenatal detection.

Congenital lower urinary tract obstruction with spontaneous fetal bladder rupture due to posterior urethral valves: a case report

BACKGROUND

Congenital lower urinary tract obstruction (LUTO) is a rare but significant condition affecting fetal urinary tract development. LUTO has a range of etiologies, with posterior urethral valves (PUV) being the most common cause. The prenatal diagnosis of LUTO plays a crucial role in recognizing the condition and guiding management decisions. Prenatal ultrasound serves as the primary tool for identifying LUTO, with key findings including megacystis, bladder wall thickening, oligohydramnios, hydronephrosis, and the 'keyhole sign' indicating dilatation of the posterior urethra. We present a case of congenital LUTO with a rare complication of spontaneous fetal bladder rupture and urinary ascites, treated by peritoneo-amniotic shunt placement.

CASE PRESENTATION

A 27-year-old pregnant Caucasian women was referred at 28 weeks of pregnancy due to the presence of megacystis and bilateral hydronephrosis on routine ultrasound and suspicion of LUTO. Repeat ultrasound at 29 weeks showed significant fetal ascites, oligohydramnios and resolution of megacystis and hydronephrosis, after which diagnosis of spontaneous bladder rupture was made. Despite ascites aspiration and amnio-infusion, there was persistent ascites and oligohydramnios. A peritoneo-amniotic shunt was placed with resolution of ascites and normalization of the amniotic fluid volume. At 35 weeks, relapse of the megacystis was observed with bilateral pyelectasis and oligohydramnios, possibly due to healing of the bladder rupture, after which elective cesarean section was planned. Cystography confirmed spontaneous healing of the bladder rupture and the presence of posterior urethral valves, which were resected in the neonatal period with cold knife incision. Total follow-up of 8 years continued to show positive ultrasonographic results and good renal function, but the child suffers from bladder dysfunction, manifesting as overactive bladder disease.

CONCLUSIONS

LUTO might lead to important renal dysfunction and pulmonary hypoplasia in case of increasing disease severity. Spontaneous bladder rupture might improve renal prognosis, acting as a pop-off mechanism by decompression of the urinary tract. However, fetal bladder rupture is rare and only few cases have been reported. Prenatal intervention can be considered for moderate or severe LUTO, but the benefit for long-term outcome remains uncertain and further studies are needed.

Postnatal surgical treatment and complications following intrauterine vesicoamniotic shunting with the SOMATEX® intrauterine shunt. A single center experience

INTRODUCTION

Intrauterine vesicoamniotic shunting (VAS) using a Somatex® shunt was shown to significantly affect survival of male fetuses with megacystis in suspected lower urinary tract obstruction (LUTO) [Figure 1]. Data on postnatal surgical management and complications are largely lacking.

OBJECTIVE

To describe the postnatal management of patients with prenatal VAS for megacystitis in suspected severe LUTO.

STUDY DESIGN

All male newborns with previous intrauterine VAS using a Somatex® shunt treated in our institution were retrospectively analyzed. We evaluated the spectrum of urethral pathologies and postnatal surgical management, especially focusing on shunt removal.

RESULTS

Between 2016 and 2022, 17 patients (all male) were treated postnatally in our institution after VAS for suspected severe LUTO. Five fetuses with dislocated shunts underwent re-implantation in utero. Overall, premature birth before the 38th week of gestation was observed in eight patients (8/17). Seven shunts could be removed without further anesthesia as a bedside procedure. Ten patients required surgical shunt removal under general anesthesia due to migration (59%). Laparoscopic shunt extraction was performed in 8/10 cases. Most frequently, dislocated shunts were located incorporated in the detrusor in eight cases and the removal required a bladder suture in 2/8 patients. In one case, the shunt was removed from the abdominal wall and in one case from the intestine wall [Figure 2]. Posterior urethral valves were found in 8/17 patients, 6/17 patients showed a urethral atresia and one patient had urethral duplication. In two patients, we identified a high grade bilateral vesicoureteral reflux without LUTO.

CONCLUSION

In our observation, more than half of the newborns with megacystis in suspected LUTO require a shunt removal surgery after early VAS using a Somatex® shunt. Urethral atresia may be found more frequently in these patients. These data should be taken into consideration for prenatal counselling of parents and planning of postnatal management.

Modelling human lower urinary tract malformations in zebrafish

Advances in molecular biology are improving our understanding of the genetic causes underlying human congenital lower urinary tract (i.e., bladder and urethral) malformations. This has recently led to the identification of the first disease-causing variants in the gene BNC2 for isolated lower urinary tract anatomical obstruction (LUTO), and of WNT3 and SLC20A1 as genes implicated in the pathogenesis of the group of conditions called bladder-exstrophy-epispadias complex (BEEC). Implicating candidate genes from human genetic data requires evidence of their influence on lower urinary tract development and evidence of the found genetic variants' pathogenicity. The zebrafish (Danio rerio) has many advantages for use as a vertebrate model organism for the lower urinary tract. Rapid reproduction with numerous offspring, comparable anatomical kidney and lower urinary tract homology, and easy genetic manipulability by Morpholino®-based knockdown or CRISPR/Cas editing are among its advantages. In addition, established marker staining for well-known molecules involved in urinary tract development using whole-mount in situ hybridization (WISH) and the usage of transgenic lines expressing fluorescent protein under a tissue-specific promoter allow easy visualization of phenotypic abnormalities of genetically modified zebrafish. Assays to examine the functionality of the excretory organs can also be modeled in vivo with the zebrafish. The approach of using these multiple techniques in zebrafish not only enables rapid and efficient investigation of candidate genes for lower urinary tract malformations derived from human data, but also cautiously allows transferability of causality from a non-mammalian vertebrate to humans.

Fetal Therapy for Renal Anhydramnios

The most severe forms of congenital anomalies of the kidney and urinary tract present in fetal life with early pregnancy renal anhydramnios and are considered lethal due to pulmonary hypoplasia without fetal therapy. Due to the high rate of additional structural anomalies, genetic abnormalities, and associated syndromes, detailed anatomic survey and genetic testing are imperative when stratifying which pregnancies are appropriate for fetal intervention. Restoring amniotic fluid around the fetus is the principal goal of prenatal treatment. The ongoing multi-center Renal Anhydramnios Fetal Therapy (RAFT) trial is assessing the safety and efficacy of serial amnioinfusions to prevent pulmonary hypoplasia so that the underlying renal disease can be addressed.

Lower urinary tract obstruction caused by fibroepithelial polyp in a newborn boy

In this rare case we report a 3-week-old boy with postnatal continues stomach pains, crying and severe dysuria, caused by bladder outlet obstruction due to a histopathological confirmed fibroepithelial polyp in the prostatic urethra. The condition was diagnosed and fully treated with ultrasound and a therapeutic cystoscopy.

Congenital Anomalies of the Kidneys and Urinary Tract

Congenital anomalies of the kidneys and urinary tract (CAKUT) are some of the most common abnormalities detected on prenatal imaging assessment. It is estimated that CAKUT comprises 20% to 30% of all major birth defects. More than 200 clinical syndromes currently include CAKUT as a component of the phenotype. This chapter outlines the evaluation and management of the most common forms of CAKUT.

Could CA 19-9 be a useful biomarker in the diagnosis, prognosis, and prediction of adequate relief in lower urinary tract obstructions?

INTRODUCTION

posterior urethral valves represent an important cause of childhood chronic kidney disease. The identification of biomarkers that indicate early kidney damage and even adequate clearance could reduce how many patients head towards kidney failure.

OBJECTIVE

this study evaluated how this easy-analysis biomarker (CA 19-9) could help identifying potential renal damage and adequate clearance in obstructive uropathies.

METHODS

46 female Wistar rats were divided into 5 groups, with different patterns of partial urinary tract obstruction: group control; group OIV: infravesical obstruction; group OIVd: infravesical obstruction with reversion, obstruction relief 7 postoperative days later; group OUu: unilateral ureteral obstruction; group OUb: bilateral ureteral obstruction. The CA 19-9s performance was compared to another biomarker: Ngal. Determination of basal CA 19-9 and Ngal in urine and blood and serum creatinine levels was performed in the rats prior to surgery (T0) and after 14 days (T1). Group OIVd underwent intermediate (Ti) collection before clearance.

RESULTS

the urinary concentration of CA 19-9 increased in groups OIV, OIVd and OUb; elevation at T1 and Ti, reached statistical significance compared to the T0 value (p<0,05). Changes in urinary CA 19-9 were more expressive in infravesical obstruction groups (AUC 0.81). Obstruction relief in group OIVd promoted significant urinary CA 19-9 reduction (p<0,05) in the final evaluation.

CONCLUSIONS

CA 19-9 urinary concentration increased in partial urinary tract obstruction. Its best performance was in the bladder neck obstruction group, in which the elevation was detected early (6 days after infravesical obstruction) and the CA19-9 urinary concentration declined after clearance.

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.

Urologic Considerations in Pediatric Chronic Kidney Disease

Common causes of pediatric ESRD are distinct from those seen in the adult population. In the pediatric population, the most common are congenital anomalies of the kidney and urinary tract (CAKUT), affecting approximately 30% of children with CKD. These structural anomalies often require coordinated care with the pediatric urology team to address voiding issues, bladder involvement, and the potential need for surgical intervention. For pediatric nephrologists and urologists, common CAKUT that are encountered include antenatal hydronephrosis, obstructive uropathies (eg, posterior urethral valves), and vesicoureteral reflux. As more pediatric patients with CAKUT, CKD, and ESRD transition to adult care, it is important for receiving adult nephrologists to understand the clinical presentation, natural history, and prognosis for these diagnoses. This review outlines the diagnosis and potential interventions for these conditions, including strategies to address bladder dysfunction that is often seen in children with CAKUT. A discussion of these management decisions (including surgical intervention) for CAKUT, which are quite common to pediatric nephrology and urology practices, may provide unique learning opportunities for adult nephrologists who lack familiarity with these pediatric conditions.

Definition, diagnosis and management of fetal lower urinary tract obstruction: consensus of the ERKNet CAKUT-Obstructive Uropathy Work Group

Fetal lower urinary tract obstruction (LUTO) is associated with high mortality and postnatal morbidity caused by lung hypoplasia and impaired kidney function. Specific diagnostic features that can guide clinical approach and decisions are lacking; thus, the European Reference Network for Rare Kidney Diseases established a work group to develop recommendations regarding the clinical definition, diagnosis and management of prenatally detected LUTO. The work group recommends the use of antero-posterior diameter of renal pelvis as the most reliable parameter for suspecting obstructive uropathies and for suspecting prenatal LUTO in the presence of fetal megacystis. Regarding prenatal and postnatal prognosis of fetuses with LUTO, the risk of fetal and neonatal death depends on the presence of oligohydramnios or anhydramnios before 20 weeks' gestation, whereas the risk of kidney replacement therapy cannot be reliably foreseen before birth. Parents of fetuses with LUTO must be referred to a tertiary obstetric centre with multidisciplinary expertise in prenatal and postnatal management of obstructive uropathies, and vesico-amniotic shunt placement should be offered in selected instances, as it increases perinatal survival of fetuses with LUTO.

Development and in-vitro characterization of a novel fetal vesicoamniotic shunt - the Vortex Shunt

OBJECTIVES

To develop and test a novel vesicoamniotic shunt (VAS) to treat fetal lower urinary tract obstruction (LUTO), decrease dislodgement and optimize shunt deployment in-vitro.

METHODS

VAS design objectives included: 1) robust and atraumatic fixation elements, 2) kink resistant conduit to adjust to fetal movement and growth, 3) one-way pressure valve to facilitate bladder cycling, and 4) echogenic deployment visualization aids. The force to dislodge the novel Vortex shunt was compared with existing commercially available shunts in a bench-top porcine bladder model. Sonographic echogenicity was evaluated with ultrasound-guided deployment, and the shunt valve pressure measured.

RESULTS

A prototype novel Vortex shunt was developed using braided nitinol "umbrella-type" ends with a kink-resistant stem incorporating an internal one-way valve. The peak force required to dislodge the Vortex shunt was significantly higher than commercially available shunts (p<0.01). Shunt deployment in the bench-top model was easily confirmed with ultrasound guidance and the brisk decompression of the inflated porcine bladder thereafter. In-vitro valve gauge pressure testing mirrored bladder pressures in human LUTO cases.

CONCLUSION

In-vitro testing shows that the Vortex shunt may improve deployment, sonographic visualization, kink resistance, and dynamic size adjustment. Validation in preclinical animal models are warranted and currently underway. This article is protected by copyright. All rights reserved.

O antígeno carboidrato CA 19-9 poderia ser um biomarcador útil no diagnóstico, prognóstico e acompanhamento da obstrução baixa do trato urinário?

RESUMO Introdução: a válvula de uretra posterior representa uma importante causa de doença renal crônica na infância. A identificação de biomarcadores que monitorem danos renais precoces e o sucesso da desobstrução do trato urinário podem reduzir o número de pacientes que evoluem para insuficiência renal. Objetivo: avaliar o desempenho do biomarcador antígeno carboidrato CA 19-9 nas obstruções parciais do trato urinário. Método: 46 ratas Wistar foram divididas em 5 grupos: grupo controle; grupo OIV: obstrução infravesical; grupo OIVd: obstrução infravesical com alívio da obstrução após 7 dias; grupo OUu: obstrução ureteral unilateral; grupo OUb: obstrução ureteral bilateral. O desempenho do CA 19-9 foi comparado a outro biomarcador, a Ngal. A dosagem de CA 19-9 e Ngal na urina e no sangue, e os níveis de creatinina sérica foram avaliados nas ratas antes da cirurgia (T0) e após 14 dias (T1). O grupo OIVd foi submetido a uma coleta intermediária (Ti). Resultados: a concentração urinária de CA19-9 aumentou nos grupos OIV, OIVd e OUb; a elevação em T1 e Ti alcançou significância estatística em relação ao valor de T0 (p<0,05). As alterações no CA 19-9 urinário foram mais expressivas nos grupos de obstrução infravesical (AUC 0,81). O alívio da obstrução no grupo OIVd promoveu redução do CA 19-9 urinário (p<0,05). Conclusões: a concentração urinária de CA19-9 aumentou na obstrução parcial do trato urinário. Seu melhor desempenho foi no grupo de obstrução infravesical, no qual a elevação foi detectada precocemente (6 dias de pós-operatório) com queda após a retirada do fator obstrutivo.

Whole Exome Sequencing in a Population With Severe Congenital Anomalies of Kidney and Urinary Tract

Fetal and neonatal interventions (e.g., amnioinfusions, amniotic shunting, and infant dialysis) have increased survival of infants with severe Congenital Anomalies of the Kidney and Urinary Tract (CAKUT), however, outcomes vary dramatically. Our aim was to perform Whole Exome Sequencing (WES) in a unique severe CAKUT population with the goal to identify new variants that will enhance prediction of postnatal outcomes. We performed trio WES on five infants with severe CAKUT (undergoing fetal interventions and/or those who initiated renal replacement therapy (RRT) within 1 month of life) and their parents as well as three singletons. We identified three potential candidate gene variants (NSUN7, MTMR3, CEP162) and validated two variants in known CAKUT genes (GATA3 and FRAS1) showing strong enrichment in this severe phenotype population. Based on our small pilot study of a unique severe CAKUT population, WES appears to be a potential tool to help predict the course of infants with severe CAKUT prenatally.

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.

Z-scores of fetal bladder size for antenatal differential diagnosis between posterior urethral valves and urethral atresia

OBJECTIVE

To construct reference values for fetal urinary bladder distension in pregnancy and use Z-scores as a diagnostic tool to differentiate posterior urethral valves (PUV) from urethral atresia (UA).

METHODS

This was a prospective cross-sectional study in healthy singleton pregnancies aimed at constructing nomograms of fetal urinary bladder diameter and volume between 15 and 35 weeks' gestation. Z-scores of longitudinal bladder diameter (LBD) were calculated and validated in a cohort of fetuses with megacystis with ascertained postnatal or postmortem diagnosis, collected from a retrospective, multicenter study. Correlations between anatomopathological findings, based on medical examination of the infant or postmortem examination, and fetal megacystis were established. The accuracy of the Z-scores was evaluated by receiver-operating-characteristics (ROC)-curve analysis.

RESULTS

Nomograms of fetal urinary bladder diameter and volume were produced from three-dimensional ultrasound volumes in 225 pregnant women between 15 and 35 weeks of gestation. A total of 1238 urinary bladder measurements were obtained. Z-scores, derived from the fetal nomograms, were calculated in 106 cases with suspected lower urinary tract obstruction (LUTO), including 76 (72%) cases with PUV, 22 (21%) cases with UA, four (4%) cases with urethral stenosis and four (4%) cases with megacystis-microcolon-intestinal hypoperistalsis syndrome. Fetuses with PUV showed a significantly lower LBD Z-score compared to those with UA (3.95 vs 8.83, P < 0.01). On ROC-curve analysis, we identified 5.2 as the optimal Z-score cut-off to differentiate fetuses with PUV from the rest of the study population (area under the curve, 0.84 (95% CI, 0.748-0.936); P < 0.01; sensitivity, 74%; specificity, 86%).

CONCLUSIONS

Z-scores of LBD can distinguish reliably fetuses with LUTO caused by PUV from those with other subtypes of LUTO, with an optimal cut-off of 5.2. This information should be useful for prenatal counseling and management of LUTO. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Fetal therapy of LUTO (lower urinary tract obstruction) - a follow-up observational study

PURPOSE

Fetal megacystis (MC) can be severe and is mainly caused by fetal lower urinary tract obstruction (LUTO). Mortality of fetal LUTO can be high as a result of pulmonary hypoplasia and/or (chronic) renal insufficiency. Several technical procedures for vesicoamniotic shunting (VAS) were developed to improve fetal MC outcomes.

MATERIAL AND METHODS

We present the outcome of nine fetuses with MC who received VAS in the prenatal period (14 + 6 to 27 + 6 weeks GA) using the Somatex^® intrauterine shunt system. MC was defined as an increased longitudinal measurement of the bladder >15 mm. The median follow-up time after birth was 18 months.

RESULTS

Eight Fetuses had uncomplicated VAS intervention. One case developed PPROM 24 h after VAS leading to abortion. Pregnancy was later terminated in further two cases. All six live-born infants received intensive care treatment. Invasive-mechanical ventilation was necessary in one case who died 24 h post-partum of severe cardiac depression. Five infants who survived the follow-up time developed chronic renal insufficiency (CRI), with one infant developing end-stage renal failure requiring peritoneal dialysis.

CONCLUSION

Overall, 5 of 9 LUTO fetuses (55%) undergoing VAS with the Somatex^® intrauterine shunt system showed long-term survival beyond the neonatal period of 28 d (5/9; 55%) with varying morbidity.

Genome-Wide Survey for Microdeletions or -Duplications in 155 Patients with Lower Urinary Tract Obstructions (LUTO)

Lower urinary tract obstruction (LUTO) is, in most cases, caused by anatomical blockage of the bladder outlet. The most common form are posterior urethral valves (PUVs), a male-limited phenotype. Here, we surveyed the genome of 155 LUTO patients to identify disease-causing CNVs. Raw intensity data were collected for CNVs detected in LUTO patients and 4.392 healthy controls using CNVPartition, QuantiSNP and PennCNV. Overlapping CNVs between patients and controls were discarded. Additional filtering implicated CNV frequency in the database of genomic variants, gene content and final visual inspection detecting 37 ultra-rare CNVs. After, prioritization qPCR analysis confirmed 3 microduplications, all detected in PUV patients. One microduplication (5q23.2) occurred de novo in the two remaining microduplications found on chromosome 1p36.21 and 10q23.31. Parental DNA was not available for segregation analysis. All three duplications comprised 11 coding genes: four human specific lncRNA and one microRNA. Three coding genes (FBLIM1, SLC16A12, SNCAIP) and the microRNA MIR107 have previously been shown to be expressed in the developing urinary tract of mouse embryos. We propose that duplications, rare or de novo, contribute to PUV formation, a male-limited phenotype.

Predictive accuracy of prenatal ultrasound findings for lower urinary tract obstruction: A systematic review and Bayesian meta-analysis

BACKGROUND

Lower urinary tract obstruction (LUTO) is a rare but critical fetal diagnosis. Different ultrasound markers have been reported with varying sensitivity and specificity.

AIMS

The objective of this systematic review and meta-analysis was to identify the diagnostic accuracy of ultrasound markers for LUTO.

MATERIALS AND METHODS

We performed a systematic literature review of studies reporting on fetuses with hydronephrosis or a prenatally suspected and/or postnatally confirmed diagnosis of LUTO. Bayesian bivariate random effects meta-analytic models were fitted, and we calculated posterior means and 95% credible intervals for the pooled diagnostic odds ratio (DOR).

RESULTS

A total of 36,189 studies were identified; 636 studies were available for full text review and a total of 42 studies were included in the Bayesian meta-analysis. Among the ultrasound signs assessed, megacystis (DOR 49.15, [15.28, 177.44]), bilateral hydroureteronephrosis (DOR 41.33, [13.36,164.83]), bladder thickening (DOR 13.73, [1.23, 115.20]), bilateral hydronephrosis (DOR 8.36 [3.17, 21.91]), male sex (DOR 8.08 [3.05, 22.82]), oligo- or anhydramnios (DOR 7.75 [4.23, 14.46]), and urinoma (DOR 7.47 [1.14, 33.18]) were found to be predictive of LUTO (Table 1). The predictive sensitivities and specificities however are low and wide study heterogeneity existed.

DISCUSSION

Classically, LUTO is suspected in the presence of prenatally detected megacystis with a dilated posterior urethra (i.e., the keyhole sign), and bilateral hydroureteronephrosis. However, keyhole sign has been found to have modest diagnostic performance in predicting the presence of LUTO in the literature which we confirmed in our analysis. The surprisingly low specificity may be influenced by several factors, including the degree of obstruction, and the diligence of the sonographer at searching for and documenting it during the scan. As a result, providers should consider this when establishing the differential for a fetus with hydronephrosis as the presence or absence of keyhole sign does not reliably rule in or rule out LUTO.

CONCLUSIONS

Megacystis, bilateral hydroureteronephrosis and bladder wall thickening are the most accurate predictors of LUTO. Given the significant consequences of a missed LUTO diagnosis, clinicians providing counselling for prenatal hydronephrosis should maintain a low threshold for considering LUTO as part of the differential diagnosis.

Evaluation of polyuria and polydipsia along with other established prognostic factors in posterior urethral valves for progression to kidney failure: experience from a developing country

BACKGROUND

Up to 50% of children with posterior urethral valves (PUV) progress to kidney failure. This study aimed to evaluate polyuria and polydipsia and other established variables with later development of kidney failure in children with PUV.

METHODS

Retrospective analysis of 297 children with PUV who underwent ablation of valves between January 1992 and January 2015 at our tertiary care center. Patients were divided into two groups: those who developed kidney failure (group 1) and those who did not (group 2). Specific prognostic factors for progression to kidney failure were analyzed including age at presentation < 1 year, nadir serum creatinine > 1.0 mg/dl, bilateral grade 3 or higher VUR at diagnosis, recurrent febrile UTIs, severe bladder dysfunction, polyuria, and polydipsia.

RESULTS

Thirty-eight (12.8%) patients progressed to kidney failure. Twenty-four and 64 patients were polyuric in group 1 and group 2 respectively (p < 0.001, Z-4.4666). Twenty-two and 61 patients were polydipsic in both groups respectively (p < 0.001). On univariate analysis, predicting variables were as follows: age at presentation < 1 year (p < 0.001), nadir serum creatinine > 1 mg/dl (p < 0.001), B/L high-grade VUR (p < 0.001), severe bladder dysfunction (p < 0.001), recurrent febrile UTIs (p = 0.002), polyuria (p < 0.001), and polydipsia (p < 0.001). On multivariate Cox regression analysis, severe bladder dysfunction, recurrent febrile UTIs, polyuria, and polydipsia were identified as significant prognostic factors predictive of ultimate progression to kidney failure.

CONCLUSION

Polyuria and polydipsia along with recurrent febrile UTI and bladder dysfunction are major prognostic factors affecting long-term kidney outcome in cases of PUV. Graphical abstract.

Novel scoring system for determining fetal candidacy for prenatal intervention for severe congenital lower urinary tract obstruction

OBJECTIVES

To evaluate a novel scoring system that combines several prenatal parameters for selecting ideal candidates for fetal intervention, and for predicting postnatal survival in patients with severe fetal lower urinary tract obstruction (LUTO).

METHODS

We retrospectively reviewed all cases of severe LUTO evaluated for fetal intervention in a single large fetal center between January 2013 and December 2017. A scoring system for determining fetal candidacy for intervention was retrospectively developed based on postnatal outcomes. The proposed scoring system included fetal urinary biochemistry, renal ultrasound parameters, initial bladder volume, and degree of bladder refill. Relevant demographic characteristics, ultrasound reports and laboratory results were reviewed. Receiver operating characteristic (ROC) curves were used to select the cut-off values for initial bladder volume and degree of bladder refill and to evaluate the performance of the scoring system in predicting postnatal death.

RESULTS

Of the 79 LUTO patients evaluated, 31 were eligible for the study. The overall 6-month postnatal survival was 64.5 % (20/31). A scoring system (0-8) was suggested with 2 points for unfavorable biochemistry, 4 points for ultrasound evidence of dysplastic kidneys, 1 point for inadequate initial bladder volume and 1 point for inadequate bladder refill. Scores>3 (N = 7) were associated with 0 % 6-month survival. The ROC curve for predicting postnatal mortality showed area under curve (AUC) of 0.82 (95 % CI 0.65-0.99). Subgroup analysis within subjects who underwent fetal intervention (N = 22) also confirmed the significance of the distribution of the scoring system between groups who survived and those who did not after adjustment for GA at delivery (p = 0.01).

CONCLUSION

We propose a novel scoring system for antenatal evaluation of patients with severe LUTO which may be useful in selecting those candidates most appropriate for intervention and in counseling parents about predicted postnatal outcome.

Fetal interventions for congenital renal anomalies

Congenital abnormalities of the kidney and urinary tract (CAKUT) represent 20% of prenatally diagnosed congenital abnormalities. Although the majority of these abnormalities do not require intervention either pre or postnatally, there is a subset of patients whose disease is so severe that it may warrant intervention prior to delivery to prevent morbidity and mortality. These cases consist of patients with moderate lower urinary tract obstruction (LUTO) in which vesicocentesis, shunting or cystoscopy are options and patients with early pregnancy renal anhydramnios (EPRA) in whom amnioinfusion therapy may be an option. The main causes of EPRA are congenital bilateral renal agenesis (CoBRA), cystic kidney disease (CKD) and severe LUTO. Untreated, EPRA is universally fatal secondary to anhydramnios induced pulmonary hypoplasia. The evidence regarding therapy for LUTO is limited and the stopped early PLUTO (Percutaneous Shunting in Lower Urinary Tract Obstruction) trial was unable to provide definitive answers about patient selection. Evidence for EPRA therapy is also scant. Serial amnioinfusions have shown promise in cases of EPRA due to CoBRA or renal failure and this treatment modality forms the basis of the ongoing NIH funded RAFT (Renal Anhydramnios Fetal Therapy) trial. At present, there is consensus that treatment for EPRA should only occur in the setting of a clinical trial.

Therapeutic intervention for fetal lower urinary tract obstruction: Current evidence and future strategies

In-utero vesica-amniotic shunting for fetal lower urinary obstruction (LUTO) is known to improve perinatal survival. More recently, studies including centres performing fetal cystoscopy, have suggested benefit on longer-term survival and renal outcome - within the limitations of small numbers and limited follow-up. These interventions carry significant risk, and therefore patient selection, and optimal timing, are key. The aim of this article is to explore ways of improving the accuracy of prenatal diagnosis, and of identifying risk factors for fetal and postnatal renal failure. The next step is that of using established staging and classification systems to select the patient group that may benefit from intervention, based on published outcomes. Several factors come into play when selecting the timing of intervention, especially if the aim is that of renal, and not only pulmonary, preservation. Lastly, current technologies and their shortfalls are discussed.

Postnatal Management in Congenital Lower Urinary Tract Obstruction With and Without Prenatal Vesicoamniotic Shunt

Purpose: Congenital lower urinary tract obstruction (cLUTO) includes a heterogeneous group of conditions caused by a functional or mechanical outlet obstruction. Early vesicoamniotic shunting (VAS) possibly reduces the burden of renal impairment. Postpartum, pediatric urologists are confronted with neonates who have a shunt in place and a potentially impassable urethra with a narrow caliber. Early management of these patients can be challenging. Here, we would like to share the approach we have developed over time. Materials and Methods: We conducted a single-center retrospective analysis from 2016 to 2020 and included all patients diagnosed with cLUTO. Data focusing on time point and type of intervention was collected. Furthermore, patients with temporary diversion via a percutaneous VAS were selected for a more detailed review. Results: In total, 71 cases of cLUTO were identified during the study period. Within this group, 31 neonates received postnatal management and surgical intervention in our center. VAS was performed in 55% of these cases (N = 17). The postnatal treatment varied between transurethral or suprapubic catheterization and early Blocksom vesicostomy. In five infants with VAS, the urinary drainage was secured through the existing VAS by inserting a gastric tube (N = 1) or a 4.8 Fr JJ-stent (N = 4). To our knowledge, this is the first report of a stent-in-stent scheme, which can remain indwelling until the definite treatment. Conclusion: Having a secure urine drainage through a VAS allows the often premature infant to grow until definite surgery can be performed. This avoids placing a vesicostomy, which requires anesthesia.

Fetal bladder outflow obstruction: Interventions, outcomes and management uncertainties

Fetal lower urinary tract obstruction (LUTO) is classically based on prenatal ultrasound identification of a dilated/ thick-walled bladder, bilateral hydronephrosis, dilated ureters and a dilated posterior urethra (also known as the "keyhole sign") in a male fetus. Although the most common underlying diagnosis is posterior urethral valves, the prenatal appearance may be similar with urethral atresia or stenosis, the Prune-Belly Syndrome, or even a cloacal anomaly in a female. These conditions form part of the Congenital Anomalies of Kidney and Urinary Tract (CAKUT) spectrum, which is the commonest cause of end-stage renal disease in children. Although it is difficult to predict postnatal renal function from the prenatal appearance, studies have recently identified predictive features (based on ultrasound findings and fetal biochemistry), and established staging systems to assist with counselling, and, where indicated, patient selection for in-utero intervention. Current in-utero therapy includes amnio-infusion, vesico-amniotic shunting, and fetal cystoscopy with valve ablation or urethral stenting. Postnatal survival and renal functional outcomes, complications and management uncertainties are described, highlighting areas of future development.

Decreased biventricular myocardial deformation in fetuses with lower urinary tract obstruction

BACKGROUND

To observe myocardial deformations in fetuses with isolated lower urinary tract obstruction (LUTO) and identify the correlation between myocardial deformation and the severity of obstruction.

METHODS

The strain (S), strain rate in systole (SRs) and strain rate in diastole (SRd) of the left and right ventricles at the first examination were prospectively analyzed and compared between fetuses with isolated LUTO and gestational age (GA)-matched normal control fetuses. Multiple regression analyses were used to assess the obstructive factors for impaired strain and strain rate, and the independent variables included bladder volume, sum of the bilateral pelvic diameters, sum of the bilateral ureteral diameters, mean bilateral renal artery pulsatility index, and amniotic fluid index.

RESULTS

Thirty-six fetuses with isolated LUTO and 36 normal controls were enrolled. Overall, decreased S, SRs and SRd of both ventricles were noted in fetuses with LUTO (p < 0.001). Moreover, S and SR were significantly negatively related to distended bladder volume (p < 0.001).

CONCLUSIONS

Fetuses with LUTO demonstrated decreased left and right myocardial deformation, and this impaired cardiac dysfunction was correlated with the urinary bladder volume. Evaluating the myocardial deformation in fetal LUTO could provide information to aid in parental counselling and intervention monitoring.

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.

Prenatal regenerative fetoscopic interventions for congenital anomalies

Fetal intervention has progressed in the past two decades from experimental proof-of-concept to practice-adopted, life saving interventions in human fetuses with congenital anomalies. This progress is informed by advances in innovative research, prenatal diagnosis, and fetal surgical techniques. Invasive open hysterotomy, associated with notable maternal-fetal risks, is steadily replaced by less invasive fetoscopic alternatives. A better understanding of the natural history and pathophysiology of congenital diseases has advanced the prenatal regenerative paradigm. By altering the natural course of disease through regrowth or redevelopment of malformed fetal organs, prenatal regenerative medicine has transformed maternal-fetal care. This review discusses the uses of regenerative medicine in the prenatal diagnosis and management of three congenital diseases: congenital diaphragmatic hernia, lower urinary tract obstruction, and spina bifida.

[Case report of an infant hyperkalemia: Suggestion of a hospital procedure for the milk pretreatment with sodium polystyrene sulfonate resin]

Sodium polystyrene sulfonate (SPS) is used to reduce intestinal potassium absorption in hyperkalemia during conservative management of chronic renal failure in infants. Milk can be pretreated by SPS to reduce the risk of enteropathy associated with oral or rectal administration. We report the case of an infant for whom this pre-treatment has been implemented. The objective of this work was to define the hospital procedure for the pre-treatment of milk by the SPS. This pre-treatment involves both a drug and infant milk. Each product has its own regulation and their processes do not normally cross each other. The roles of each contributor were therefore defined: prescription of pre-treated milk (dose of SPS and volume of milk) by the physician, dispensing of SPS by the pharmacist, delivery of milk by the milk kitchen staff, pre-treatment by a nurse and administration by a nursing auxiliary. The preparation of the bottles is as follows: placing approximately 1g of SPS per 100mL of milk in contact, stirring, resting in the refrigerator for one hour, taking the supernatant to be administered. In the reported case, serum potassium levels were reduced from 5.57mmol/L before treatment to 4.53mmol/L after treatment, in line with the 20% decrease found in the literature. This method of administration is beneficial in terms of tolerance and acceptability. The preparation is simple and allows going back home under treatment.

Neurodevelopmental Outcome in Infants with Lower Urinary Tract Obstruction Based on Different Degrees of Severity

OBJECTIVE

To determine postnatal neurodevelopmental (ND) outcomes for children with congenital lower urinary tract obstruction (LUTO) based on disease severity.

METHODS

Twenty male infants with LUTO were classified prenatally as Stage 1 (normal amniotic fluid and renal function; n = 5), Stage 2 (signs of obstruction with preserved renal function; n = 13), and Stage 3 (signs of severe renal damage; n = 2). ND status was assessed using the Developmental Profile-3 test in 5 developmental domains (physical, adaptive behavior, social-emotional, cognitive, and communication). Each domain was considered to be delayed if standard scores were 2 or more SD below the mean. ND outcomes were compared between cases with an expected normal renal function (LUTO Stage 1) and those with impaired renal function (LUTO Stages 2 and 3). Results from cases with Stage 2 were also compared to those from Stage 3. ORs were calculated to predict risk for adverse ND outcome for each domain considering prenatal and postnatal factors.

RESULTS

Gestational age (GA) at the diagnosis of LUTO was similar between both groups (Stage 1: 24.85 ± 7.87 vs. Stages 2 and 3: 21.4 ± 4.31 weeks; p = 0.24). Twelve of 15 cases with Stage 2 or 3 underwent vesicoamniotic shunt placement compared to none of Stage 1 fetuses (p < 0.01). No differences in GA at delivery were detected between the groups (37.9 ± 1.6 vs. 35.1 ± 3.6 weeks; p = 0.1). One of the infants in the Stage 2 and 3 groups received a kidney transplant during follow-up. One case (20%) from Stage 1 group required dialysis during the first 6 months of life, and 1 case from Stage 2 to 3 group required it during the first 6 months (p = 1.0), whereas 3 additional cases needed dialysis from 6 to 24 months (p = 0.6). Mean age at Developmental Profile 3 (DP-3) testing was 20.3 ± 12.3 months (Stage 1: 11.2 ± 8.6 vs. Stages 2 and 3: 23.4 ± 13.4 months; p = 0.07). Fifteen of the 20 patients (75%) had no ND delays. Of the 5 patients with ND delays, 4 received dialysis. No differences in ND outcomes between infants with LUTO Stage 1 and those with Stages 2 and 3 were detected except for a trend toward better physical development in Stage 1 (102.6 ± 11.6 vs. 80.7 ± 34.9; p = 0.05). Infants diagnosed with LUTO Stage 3 showed significantly lower adaptive scores than those diagnosed with Stage 2 (Stage 2: 101.9 ± 22.3 vs. Stage 3: 41.5 ± 30.4; p = 0.04) and a nonsignificant trend for lower results in physical (85.8 ± 33.0 vs. 47.5 ± 38.9; p = 0.1) and socio-emotional (94.7 ±17.9 vs. 73.5 ± 13.4; p = 0.1) domains. Infants who received dialysis showed 15-fold increased risk (95% CI 0.89-251) for delayed socio-emotional development (p = 0.06). Diagnosis of fetal renal failure increased the risk for delays in the adaptive domain 30-fold (95% CI 1.29-93.1; p = 0.03). Infants with abnormal renal function had 19 times (95% CI 1.95-292) increased risk for delays in the physical domain (p = 0.03).

CONCLUSIONS

While most patients with LUTO do not exhibiting ND delays, our results support the importance of ND monitoring, especially in severe forms of LUTO, as increased severity of this condition may be associated with poorer ND outcomes.

Fetal lower urinary tract obstruction: What should we tell the prospective parents?

Fetal lower urinary tract obstruction (LUTO), which often results in marked perinatal morbidity and mortality, is caused by a heterogeneous group of anatomical defects that lead to blockage of the urethra. The classic prenatal presentation of LUTO includes megacystis with hydronephrosis. While mild forms of the disease can be associated with favorable outcomes, more severe disease commonly leads to dysplastic changes in the fetal kidneys, and ultimately oligohydramnios, which can result in secondary pulmonary hypoplasia and renal failure at birth. The aim of this review is to provide practitioners with a general overview of the diagnosis and treatment of LUTO based on disease severity, along with some points to consider when counseling prospective parents of fetuses with this condition.

Etiology and management of early pregnancy renal anhydramnios: Is there a place for serial amnioinfusions?

Early pregnancy renal anhydramios (EPRA) comprises congenital renal disease that results in fetal anhydramnios by 22 weeks of gestation. It occurs in over 1 in 2000 pregnancies and affects 1500 families in the US annually. EPRA was historically considered universally fatal due to associated pulmonary hypoplasia and neonatal respiratory failure. There are several etiologies of fetal renal failure that result in EPRA including bilateral renal agenesis, cystic kidney disease, and lower urinary tract obstruction. Appropriate sonographic evaluation is required to arrive at the appropriate urogenital diagnosis and to identify additional anomalies that allude to a specific genetic diagnosis. Genetic evaluation variably includes karyotype, microarray, targeted gene testing, panels, or whole exome sequencing depending on presentation. Patients receiving a fetal diagnosis of EPRA should be offered management options of pregnancy termination or perinatal palliative care, with the option of serial amnioinfusion therapy offered on a research basis. Preliminary data from case reports demonstrate an association between serial amnioinfusion therapy and short-term postnatal survival of EPRA, with excellent respiratory function in the neonatal period. A multicenter trial, the renal anhydramnios fetal therapy (RAFT) trial, is underway. We sought to review the initial diagnosis ultrasound findings, genetic etiologies, and current management options for EPRA.

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.

Fetal megacystis: a lot more than LUTO

OBJECTIVE

Fetal megacystis presents a challenge in terms of counseling and management because of its varied etiology and evolution. The aim of this study was to present a comprehensive overview of the underlying etiologies and structural anomalies associated with fetal megacystis.

METHODS

This was a retrospective multicenter study of cases referred to the fetal medicine unit of one of the eight academic hospitals in The Netherlands with a diagnosis of fetal megacystis. For each case, data on and measurements of fetal urinary tract and associated structural anomalies were collected. All available postmortem examinations and postnatal investigations were reviewed in order to establish the final diagnosis. In the first trimester, fetal megacystis was defined as longitudinal bladder diameter (LBD) ≥ 7 mm, and in the second and third trimesters as an enlarged bladder failing to empty during an extended ultrasound examination lasting at least 40 min.

RESULTS

Of the 541 pregnancies with fetal megacystis, it was isolated (or solely accompanied by other signs of lower urinary tract obstruction (LUTO)) in 360 (67%) cases and associated with other abnormal ultrasound findings in 181 (33%) cases. The most common associated ultrasound anomaly was an increased nuchal translucency thickness (22%), followed by single umbilical artery (10%) and cardiac defect (10%). A final diagnosis was established in 418 cases, including 222 (53%) cases with isolated LUTO and 60 (14%) infants with normal micturition or minor isolated urological anomalies. In the remaining 136 (33%) cases, concomitant developmental or chromosomal abnormality or genetic syndrome was diagnosed. Overall, 40 chromosomal abnormalities were diagnosed, including trisomy 18 (n = 24), trisomy 21 (n = 5), Turner syndrome (n = 5), trisomy 13 (n = 3) and 22q11 deletion (n = 3). Thirty-two cases presented with anorectal malformations involving the anus, rectum and urogenital tract. In cases with confirmed urethral and anal atresia, megacystis occurred early in pregnancy and the bladder appeared severely distended (the LBD (in mm) was equal to or greater than twice the gestational age (in weeks)). Fetal macrosomia was detected in six cases and an overgrowth syndrome was detected in four cases, comprising two infants with Beckwith-Wiedemann syndrome and two with Sotos syndrome. Megacystis-microcolon-intestinal hypoperistalsis syndrome was diagnosed in five (1%) cases and prenatally suspected only in one case.

CONCLUSIONS

Although the main cause of fetal megacystis is LUTO, an enlarged fetal bladder can also be present as a concomitant finding of miscellaneous genetic syndromes, developmental disturbances and chromosomal abnormalities. We provide an overview of the structural anomalies and congenital disorders associated with fetal megacystis and propose a practical guide for the differential diagnosis of genetic syndromes and chromosomal and developmental abnormalities in pregnancies presenting with fetal megacystis, focusing on the morphological examination of the fetus. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Rare Variants in BNC2 Are Implicated in Autosomal-Dominant Congenital Lower Urinary-Tract Obstruction

Congenital lower urinary-tract obstruction (LUTO) is caused by anatomical blockage of the bladder outflow tract or by functional impairment of urinary voiding. About three out of 10,000 pregnancies are affected. Although several monogenic causes of functional obstruction have been defined, it is unknown whether congenital LUTO caused by anatomical blockage has a monogenic cause. Exome sequencing in a family with four affected individuals with anatomical blockage of the urethra identified a rare nonsense variant (c.2557C>T [p.Arg853^∗]) in BNC2, encoding basonuclin 2, tracking with LUTO over three generations. Re-sequencing BNC2 in 697 individuals with LUTO revealed three further independent missense variants in three unrelated families. In human and mouse embryogenesis, basonuclin 2 was detected in lower urinary-tract rudiments. In zebrafish embryos, bnc2 was expressed in the pronephric duct and cloaca, analogs of the mammalian lower urinary tract. Experimental knockdown of Bnc2 in zebrafish caused pronephric-outlet obstruction and cloacal dilatation, phenocopying human congenital LUTO. Collectively, these results support the conclusion that variants in BNC2 are strongly implicated in LUTO etiology as a result of anatomical blockage.

Antenatal staging of congenital lower urinary tract obstruction

OBJECTIVE

To propose a staging system for congenital lower urinary tract obstruction (LUTO) capable of predicting the severity of the condition and its prognosis.

METHODS

This was a national retrospective study carried out at the eight Academic Hospitals in The Netherlands. We collected prenatal and postnatal data of fetuses at high risk of isolated LUTO that were managed conservatively. Postnatal renal function was assessed by the estimated glomerular filtration rate (eGFR), calculated using the Schwartz formula, considering the length of the infant and the creatinine nadir in the first year after birth. Receiver-operating characteristics (ROC) curve analysis, univariate analysis and multivariate logistic regression analysis with stepwise backward elimination were performed in order to identify the best antenatal predictors of perinatal mortality and postnatal renal function.

RESULTS

In total, 261 fetuses suspected of having LUTO and managed conservatively were included in the study. The pregnancy was terminated in 110 cases and perinatal death occurred in 35 cases. Gestational age at appearance of oligohydramnios showed excellent accuracy in predicting the risk of perinatal mortality with an area under the ROC curve of 0.95 (P < 0.001) and an optimal cut-off at 26 weeks' gestation. Fetuses with normal amniotic fluid (AF) volume at 26 weeks' gestation presented with low risk of poor outcome and were therefore defined as cases with mild LUTO. In fetuses referred before the 26^th week of gestation, the urinary bladder volume (BV) was the best unique predictor of perinatal mortality. ROC curve analysis identified a BV of 5.4 cm³ and appearance of oligohydramnios at 20 weeks as the best threshold for predicting an adverse outcome. LUTO cases with a BV ≥ 5.4 cm³ or abnormal AF volume before 20 weeks' gestation were defined as severe and those with BV < 5.4 cm³ and normal AF volume at the 20 weeks' scan were defined as moderate. Risk of perinatal mortality significantly increased according to the stage of severity, from mild to moderate to severe stage, from 9% to 26% to 55%, respectively. Similarly, risk of severely impaired renal function increased from 11% to 31% to 44%, for mild, moderate and severe LUTO, respectively.

CONCLUSIONS

Gestational age at appearance of oligo- or anhydramnios and BV at diagnosis can accurately predict mortality and morbidity in fetuses with LUTO. Our proposed staging system can triage reliably fetuses with LUTO and predict the severity of the condition and its prognosis. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Surgical interventions and anesthesia in the 1st year of life for lower urinary tract obstruction

BACKGROUND

Patients with a prenatal diagnosis of lower urinary tract obstruction (LUTO) may undergo prenatal interventions, such as vesicoamniotic shunt (VAS) placement, as a temporary solution for relieving urinary tract obstruction. A recent FDA communication has raised awareness of the potential neurocognitive adverse effects of anesthesia in children. We hypothesized as to whether a prenatal LUTO staging system was predictive of the number of anesthesia events for prenatally diagnosed LUTO patients.

METHODS

We retrospectively reviewed the prenatal and postnatal clinical records for patients with prenatally diagnosed LUTO from 2012 to 2015. Patients were stratified by prenatal VAS status and by LUTO disease severity according to Ruano et al. (Ultrasound Obstet Gynecol. 2016).

RESULTS

31 patients were identified with a prenatal LUTO diagnosis, and postnatal records were available for 21 patients (seven patients in each stage). When combining prenatal and postnatal anesthesia, there was a significant difference in the number of anesthesia encounters by stage (1.6, 3.7, and 6.7 for Stage I, II, and III respectively, p = .034). Upon univariate analysis, higher gestational age (GA) at birth was associated with a decreased number of anesthesia events in the first year (p = .031).

CONCLUSIONS

The majority of infants with prenatally diagnosed LUTO will undergo postnatal procedures with general anesthesia exposure in the first year of life. Patients with higher prenatal LUTO severity experienced a higher number of both prenatal and postnatal anesthesia encounters. In addition, higher GA at birth was associated with fewer anesthesia encounters in the first year.

LEVEL OF EVIDENCE

This is a prognostic study with Level IV evidence.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Current epidemiology and antenatal presentation of posterior urethral valves: Outcome of BAPS CASS National Audit

AIM

Posterior urethral valves (PUVs) are the most common cause of congenital bladder outlet obstruction (BOO) in boys and end-stage renal failure (ESRF) in childhood. In the 1980s, 1 in 4000 boys had PUV. Presentation was 1/3 antenatal/neonatally, 1/3 postnatal, 1/3 late (>1 year). This study aimed to describe the current proportions in a contemporary cohort.

METHODS

A national audit (BAPS CASS) of referrals in the UK and Ireland of boys diagnosed with suspected or confirmed PUV in a year was conducted. National registration data provided the male birth-rate. Data were presented as number (%), analysed by Mann-Whitney U-test and Chi-square test, with P < 0.05 taken as significant. The study was approved by a national ethics committee (NRES Committee South Central Oxford A (12/SC/0416)).

RESULTS

Data were collected from 1st October 2014 to 30th September 2015 from 25/26 centres on 121 cases of suspected bladder outlet obstruction (BOO), of which 113 (93%) were because of PUV. The male birth rate during the period was 432,806/year. The calculated incidence of BOO was 1/3580 and for PUV was 1/3800 per-annum. The proportion of PUV presenting according to age was: antenatally (n = 40, 35%), infancy (n = 47, 42%), and late (n = 26, 23%). Plasma creatinine was higher in antenatally-diagnosed BOO vs. postnatal, 54 (39.5-109.5) μmol/l vs. 34(21-47) μmol/l, P = 0.0005. Hydronephrosis and ureteric dilatation were significantly greater in antenatally diagnosed BOO vs. postnatal vs. late. Renal dysplasia (cortical thinning, poor corticomedullary differentiation, or renal cysts) was significantly more likely in antenatally diagnosed BOO.

CONCLUSION

Neither the incidence (~1/4000) nor the proportion antenatally diagnosed (~1/3) of boys with PUV appears to have changed in the past 30 years. Those boys who were antenatally diagnosed have significantly higher postnatal plasma creatinine, more hydroureteronephrosis, and renal dysplasia than those diagnosed in infancy or later. It may be hypothesized that this is the reason they are detected antenatally.

LEVEL OF EVIDENCE

Prognosis study - Level I - prospective national cohort study.