Congenital obstructive uropathy: its origin and contribution to end-stage renal disease in children

Appearance of the bladder on initial voiding cystogram in boys with PUV and its relation to pre and postnatal findings

Introduction

Bladder profile in boys with Posterior Urethral Valves can be very varied with a spectrum going from high pressure, unstable, hypocompliant small bladders to hypercompliant, large acontractile bladders, with some being near-normal. Our question was whether appearance, specifically of the bladder, on initial VCUG was correlated to prenatal features and whether it could predict early postnatal outcome.

Method

We used a prospectively gathered database of boys with prenatally suspected PUV. We analyzed whether the appearance, specifically of the bladder, was related to date of prenatal diagnosis, presence of a megacystis on prenatal ultrasound, presence of vesico-ureteral reflux (VUR), presence of abnormal DMSA scan, nadir creatinine or presence of febrile urinary tract infection (fUTI) during the first two years of life.

Results

The database comprised 90 cystograms. 15% of bladders were judged normal/regular, 54 % were small/diverticular and 31% were large/diverticular. Bladder appearance was not associated with presence of prenatal megacystis, abnormal DMSA scan, VUR, nor rate of fUTI. The only significant associations were normal/regular bladder and early prenatal diagnosis (p = 0.04) and normal/regular bladder and elevated nadir creatinine (>75µmol/l) (p = 0.01).

Discussion

We believe that when focusing solely on the appearance of the bladder, excluding information about the urethra and presence of reflux, the cystogram alone is insufficient to inform on future bladder function. This could be used as an argument in favor of performing early urodynamics in this population.

Posterior Urethral Valves, Unilateral Vesicoureteral Reflux, and Renal Dysplasia (VURD) Syndrome: Long-Term Longitudinal Evaluation of the Kidney Function

The presence of unilateral vesicoureteral reflux (VUR), and renal dysplasia associated with posterior urethral valves (PUV) (VURD syndrome) was believed to represent a pressure-released pop-off mechanism protecting kidney function. We aimed to investigate its role with respect to long-term kidney function in a cross-sectional and longitudinal analysis. We compared the iohexol glomerular filtration rate (GFR) measured at 5 (GFR5) and 10 (GFR10) years of age in children with (Group A) and without (Group B) VURD syndrome, who underwent PUV resection under 2 years of age. VURD syndrome was diagnosed in cases of unilateral loss of kidney function (<15% on nuclear medicine test) associated with ipsilateral grade IV-V VUR. VURD syndrome was diagnosed in 16 (12.8%) out of 125 patients who met the inclusion criteria. While the median GFR5 was similar in the 2 groups [Group A: 87.3 (74.7-101.2) mL/min/1.73 m2 vs. Group B: 99.6 (77-113) mL/min/1.73 m2, p-value: 0.181], the median GFR10 values were significantly lower in children with VURD syndrome [Group A: 75.7 (71.2-85.9) mL/min/1.73 m2 vs. Group B: 95.1 (81.2-114.2) mL/min/1.73 m2, p-value: 0.009]. Similar results were obtained in a longitudinal analysis of the children with GFR measurement available both at 5 and 10 years of age [GFR5 in Group A: 93.1 (76.9-103.5) mL/min/1.73 m2 vs. Group B: 97.5 (80-113) mL/min/1.73 m2, p-value: 0.460; GFR10: Group A: 71.9 (71.9-85.9) mL/min/1.73 m2 vs. Group B: 94.8 (81.5-110.6) mL/min/1.73 m2, p-value: 0.024]. In conclusion, VURD syndrome does not show a protective role in kidney function preservation. On the contrary, it seems to be associated with a deterioration of the kidney function on a long-term follow-up.

Development of the Urinary Tract in Fetal Rats: A Micro-CT Study

INTRODUCTION

 Micro-computed tomography (micro-CT) is an established tool to study fetal development in rodents. This study aimed to use micro-CT imaging to visualize the development of the urinary tract in fetal rats.

MATERIALS AND METHODS

 Fetal rats from embryonic day (ED) 15, ED17, ED19, ED21, and N0 (newborn) (n = 6 per group; 3 males) were fixed and desiccated using the "critical point" technique. We utilized the micro-CT system (SkyScan) and analyzed the resulting scans with CTAn, DataViewer, and ImageJ to visualize the morphology and quantify the volumes of kidney, bladder, adrenal gland, as well as length of the ureter.

RESULTS

 High-resolution micro-CT showed continuous growth of both kidneys from ED15 to N0, with the highest increase between ED19 and ED21. The length of the ureter increased from ED15 to ED21 and remained stable until birth. The volume of the bladder steadily increased from ED15 to N0.In females, a statistically higher volume of the adrenal gland on ED21 was observed, whereas no sex-specific differences were seen for kidney, ureter, and bladder development.

CONCLUSION

 Micro-CT depicts an excellent tool to study urinary tract development in the fetal and neonatal rat. It enables the metric quantification of longitudinal anatomic changes in high definition without previous destructive tissue preparation. The present study revealed sex-specific differences of the adrenal gland development and provides comprehensive data for the understanding of fetal urinary tract development, inspiring future research on congenital urological malformations.

Risk factors for febrile urinary tract infection in boys with posterior urethral valves

OBJECTIVE

Boys with posterior urethral valves (PUV) present an increased risk of febrile urinary tract infection (fUTI). Identifying specific risk factors could allow for tailoring UTI prevention. The aim of this study was to use the data from the CIRCUP randomized controlled trial data to identify patient characteristics associated with a higher risk of fUTI.

PATIENTS AND METHODS

We performed a secondary analysis of the data from the CIRCUP randomized trial which included boys with PUV, randomized to circumcision and antibiotic prophylaxis vs. antibiotic prophylaxis alone and followed for 2 years. There was only 1 episode of fUTI in the circumcision group vs. 17 in the uncircumcised group. We therefore only studied the antibiotic prophylaxis alone group and compared age at prenatal diagnosis, size and weight at birth, presence of dilating VUR at diagnosis, abnormal DMSA scan at 2 months, and nadir creatinine between children who presented a fUTI and those who did not, as well as age at first episode of fUTI.

RESULTS

The study group consisted of 42 patients of which 17 presented at least on fUTI. Presence of dilating VUR was significantly associated with risk of fUTI (p = 0.03), OR: 6 [CI 95% = (1.13-27.52)]. None of the other parameters were associated with increased risk of fUTI. We observed three distinct time periods for presenting a fUTI with a decrease in infection rate after the first 40 days of life, then at 240 days of life.

CONCLUSION

In boys with PUV, presence of high-grade VUR is associated with a higher risk of presenting a fUTI. The rate of febrile UTIs seems to decrease after 9 months.

Circumcision and Risk of Febrile Urinary Tract Infection in Boys with Posterior Urethral Valves: Result of the CIRCUP Randomized Trial

BACKGROUND

Boys with posterior urethral valves (PUVs) have an increased risk of febrile urinary tract infections (fUTIs). Circumcision is believed to reduce the risk of fUTIs in boys, although there are no randomized trials demonstrating this.

OBJECTIVE

To determine the effect of circumcision on the risk of fUTIs in boys with PUVs.

DESIGN, SETTING, AND PARTICIPANTS

A clinical randomized trial that ran between August 2012 and July 2017 was conducted. The trial was multicentric, including 13 referral centers for pediatric urology. Male boys, aged 1-28 d, diagnosed with posterior urethral valves, confirmed by voiding cystogram, were included. The exclusion criteria included presence of a genital malformation contraindicating performing a circumcision.

INTERVENTION

Participants were randomized to neonatal circumcision + antibiotic prophylaxis (CATB) or antibiotic prophylaxis alone (ATB), and followed for 2 yr.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary outcome was a risk of presenting fUTIs in each group. An fUTI was defined as fever (>38.5 °C) with evidence of pyuria and culture-proven infection on urinalysis, obtained by urethral catheterization or suprapubic aspiration. A bivariate analysis of the primary outcome was performed using the Kaplan-Meier method.

RESULTS AND LIMITATIONS

In total, 91 patients were included: 49 in group CATB and 42 in group ATB. The probability of presenting an fUTI was 20% in group ATB versus 3% in group CATB. The hazard ratio of presenting an fUTI within 2 yr in the ATB group compared with that in the CATB group was 10.3 (95% confidence interval: 1.3-82.5). Sixty-four children (70.3%) had a complete follow-up at 2 yr of age.

CONCLUSIONS

Circumcision significantly decreases the risk of presenting an fUTI in boys with PUVs.

PATIENT SUMMARY

In this report, we compared, in a multicentric trial, the number of febrile urinary tract infections (UTIs) in boys with posterior urethral valves who had either antibiotic prophylaxis alone or antibiotic prophylaxis and circumcision. We found that those who had a circumcision had a significantly lower risk of febrile UTIs.

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 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.

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).

Reciprocal Spatiotemporally Controlled Apoptosis Regulates Wolffian Duct Cloaca Fusion

The epithelial Wolffian duct (WD) inserts into the cloaca (primitive bladder) before metanephric kidney development, thereby establishing the initial plumbing for eventual joining of the ureters and bladder. Defects in this process cause common anomalies in the spectrum of congenital anomalies of the kidney and urinary tract (CAKUT). However, developmental, cellular, and molecular mechanisms of WD-cloaca fusion are poorly understood. Through systematic analysis of early WD tip development in mice, we discovered that a novel process of spatiotemporally regulated apoptosis in WD and cloaca was necessary for WD-cloaca fusion. Aberrant RET tyrosine kinase signaling through tyrosine (Y) 1062, to which PI3K- or ERK-activating proteins dock, or Y1015, to which PLCγ docks, has been shown to cause CAKUT-like defects. Cloacal apoptosis did not occur in RetY1062F mutants, in which WDs did not reach the cloaca, or in RetY1015F mutants, in which WD tips reached the cloaca but did not fuse. Moreover, inhibition of ERK or apoptosis prevented WD-cloaca fusion in cultures, and WD-specific genetic deletion of YAP attenuated cloacal apoptosis and WD-cloacal fusion in vivo Thus, cloacal apoptosis requires direct contact and signals from the WD tip and is necessary for WD-cloacal fusion. These findings may explain the mechanisms of many CAKUT.

Lower urinary tract obstruction: fetal intervention based on prenatal staging

The authors present an overview of lower urinary tract obstruction (LUTO) in the fetus with a particular focus on the insult to the developing renal system. Diagnostic criteria along with the challenges in estimating long-term prognosis are reviewed. A proposed prenatal LUTO disease severity classification to guide management decisions with fetal intervention to maintain or salvage in utero and neonatal pulmonary and renal function is also discussed. Stage I LUTO (mild form) is characterized by normal amniotic fluid index after 18 weeks, normal kidney echogenicity, no renal cortical cysts, no evidence of renal dysplasia, and favorable urinary biochemistries when sampled between 18 and 30 weeks; prenatal surveillance is recommended. Stage II LUTO is characterized by oligohydramnios/anhydramnios, hyperechogenic kidneys but absent renal cortical cysts or apparent signs of renal dysplasia and favorable fetal urinary biochemistry; fetal vesicoamniotic shunting (VAS) or fetal cystoscopy is indicated to prevent pulmonary hypoplasia and renal failure. Stage III LUTO is oligohydramnios/anhydramnios, hyperechogenic kidneys with cortical cysts and renal dysplasia and unfavorable fetal urinary biochemistry after serial evaluation; fetal vesicoamniotic shunt may prevent severe pulmonary hypoplasia but not renal failure. Stage IV is characterized by intrauterine fetal renal failure, defined by anhydramnios and ultrasound (US) findings suggestive of severe renal dysplasia, and is associated with death in 24 h of life or end-stage renal disease (ESRD) within the first week of life; fetal vesicoamniotic shunt and fetal cystoscopy are not indicated.

Fetal surgery: a critical review

Therapeutic fetal surgical procedures are predicated upon the ability to make an accurate fetal diagnosis. The earliest open fetal surgical procedures were introduced in the 1960s to treat Rh isoimmunisation. They were introduced when it became possible to predict impending fetal demise. Open procedures were abandoned when percutaneous approaches proved superior. The introduction of fetal ultrasound allowed the diagnosis of other congenital anomalies, some being amenable to fetal interventions. Open fetal surgical procedures were initially utilised, with significant maternal morbidity. For some anomalies, percutaneous approaches became favoured. In general, all of these procedures involved significant risks to the mother, to save a baby that was likely to die before or shortly after birth without fetal intervention. Fetal repair for myelomeningocele was a "sea change" in approach. The same maternal risks were taken to improve the quality of life of the affected fetus, not save its life. The completion of the "MOMs Trial" has occasioned a "tsunami" of centres in North America applying this approach. Others are attempting percutaneous repairs, with mixed results. This paper reviews the history of fetal surgery, focusing on the themes of the tension between accurate diagnosis and prognosis and open versus "minimally invasive" approaches.

Fibroproliferative response to urothelial failure obliterates the ureter lumen in a mouse model of prenatal congenital obstructive nephropathy

Congenital obstructive nephropathy (CON) is the most prevalent cause of pediatric chronic kidney disease and end-stage renal disease. The ureteropelvic junction (UPJ) region, where the renal pelvis transitions to the ureter, is the most commonly obstructed site in CON. The underlying causes of congenital UPJ obstructions remain poorly understood, especially when they occur in utero, in part due to the lack of genetic animal models. We previously showed that conditional inactivation of Sec10, a central subunit of the exocyst complex, in the epithelial cells of the ureter and renal collecting system resulted in late gestational bilateral UPJ obstructions with neonatal anuria and death. In this study, we show that without Sec10, the urothelial progenitor cells that line the ureter fail to differentiate into superficial cells, which are responsible for producing uroplakin plaques on the luminal surface. These Sec10-knockout urothelial cells undergo cell death by E17.5 and the urothelial barrier becomes leaky to luminal fluid. Also at E17.5, we measured increased expression of TGFβ1 and genes associated with myofibroblast activation, with evidence of stromal remodeling. Our findings support the model that a defective urothelial barrier allows urine to induce a fibrotic wound healing mechanism, which may contribute to human prenatal UPJ obstructions.

Urothelial Defects from Targeted Inactivation of Exocyst Sec10 in Mice Cause Ureteropelvic Junction Obstructions

Most cases of congenital obstructive nephropathy are the result of ureteropelvic junction obstructions, and despite their high prevalence, we have a poor understanding of their etiology and scarcity of genetic models. The eight-protein exocyst complex regulates polarized exocytosis of intracellular vesicles in a large variety of cell types. Here we report generation of a conditional knockout mouse for Sec10, a central component of the exocyst, which is the first conditional allele for any exocyst gene. Inactivation of Sec10 in ureteric bud-derived cells using Ksp1.3-Cre mice resulted in severe bilateral hydronephrosis and complete anuria in newborns, with death occurring 6-14 hours after birth. Sec10 FL/FL;Ksp-Cre embryos developed ureteropelvic junction obstructions between E17.5 and E18.5 as a result of degeneration of the urothelium and subsequent overgrowth by surrounding mesenchymal cells. The urothelial cell layer that lines the urinary tract must maintain a hydrophobic luminal barrier again urine while remaining highly stretchable. This barrier is largely established by production of uroplakin proteins that are transported to the apical surface to establish large plaques. By E16.5, Sec10 FL/FL;Ksp-Cre ureter and pelvic urothelium showed decreased uroplakin-3 protein at the luminal surface, and complete absence of uroplakin-3 by E17.5. Affected urothelium at the UPJ showed irregular barriers that exposed the smooth muscle layer to urine, suggesting this may trigger the surrounding mesenchymal cells to overgrow the lumen. Findings from this novel mouse model show Sec10 is critical for the development of the urothelium in ureters, and provides experimental evidence that failure of this urothelial barrier may contribute to human congenital urinary tract obstructions.

An analysis of long-term occurrence of renal complications following pediatric pyeloplasty

OBJECTIVE

Few reports discuss post-pubertal renal complications after pyeloplasty. We analyzed long-term complications, such as decreased renal function (RF) measured by serum creatinine (SCr), hypertension (HTN), or proteinuria (protU) following pediatric pyeloplasty.

SUBJECTS AND METHODS

We retrospectively investigated 257 patients who underwent dismembered pyeloplasty due to ureteropelvic junction obstruction from January 1986 to December 2001. Medical history, preoperative and postoperative blood pressure, urinalysis, and SCr results were reviewed.

RESULTS

Fifty-five patients (47 male, 8 female) who were followed up for at least 10 years with post-pubertal follow-up data available were analyzed. Seven (12.7%) patients were diagnosed with HTN, and 10 (18.2%) with protU. The grade of hydronephrosis decreased, and the differential RF measured by MAG-3 renal scan significantly increased at final analysis (p<0.001). Presence of preoperative symptoms (p=0.034), and SCr elevation (p=0.018) showed correlation with HTN. HTN took 15.7 (±5.8) (7-25) years, and protU detection took 16.2 (±5.9) (6-23) years, with the highest incidence of both HTN and protU between 15 and 20 years postoperatively.

CONCLUSION

According to our investigation, a prudent evaluation of signs of RF decrease at 10 years after surgery, and then every 5 years, until 20 years should be recommended, although further studies are necessary.

Posterior urethral valves: Persistent renin angiotensin system activation after valve ablation and role of pre-emptive therapy with angiotensin converting enzyme-inhibitors on renal recovery

Aim:

To study renin angiotensin system (RAS) activity after posterior urethral valve ablation and the role of early induction of angiotensin converting enzyme-inhibitors (ACE-I) on the outcome of renal function.

Materials and Methods:

Thirty four children underwent valve ablation in which therapy with ACE-I was started 40.5 ± 4.1 (range 32-47 months) formed the study group. Post-ACE-I data were collected after mean duration of 18.2 ± 4.0 (12-28 months). Plasma renin activity (PRA), urinary micro albumin, glomerular filtration rate (GFR), and serum creatinine, before and after therapy were monitored.

Results:

Therapy with ACE-I resulted in a fall in micro albuminuria by 45.7% and 42.0% in patients without and with vesico ureteral reflux, respectively, and improvement in split renal function by 6.6% and 5.9% GFR respectively. A similar response was noted in patients without and with renal scars.

Conclusion:

The decline in renal function after valve ablation is accompanied by activation of RAS reflected in a gradual rise in PRA. Therapy with ACE-I stabilizes and then improves renal function, thereby, retarding the pace of renal damage.

Hydronephrosis in pediatric kidney transplant: clinical relevance to graft outcome

OBJECTIVE

To evaluate our pediatric renal transplant patient population at the Children's Hospital of Pittsburgh to better understand the clinical significance of hydronephrosis.

MATERIALS AND METHODS

We retrospectively reviewed records of patients who had received a renal transplant in 1998-2008. Exclusion criteria included multi-organ transplants and allograft failure within 3-months. We determined the incidence of hydronephrosis and compared serum creatinine, incidence of pyelonephritis, rejection and vesicoureteral reflux between the hydronephrotic and non-hydronephrotic cohorts. Data were analyzed using descriptive statistics, Student's t-test and Pearson Chi-Square test.

RESULTS

51 patients (35 male, 68.6%) were identified. The mean age at time of transplant was 8.7 ± 5.9 years and the mean follow-up period was 45.2 ± 45.4 months. Common causes of renal failure included posterior urethral valves, renal dysplasia, reflux and prune belly syndrome. Twenty-five (49%) patients developed hydronephrosis. This was associated with worsening renal function (p = 0.008). Hydronephrosis was also associated with pyelonephritis (p = 0.03) and male gender (p = 0.004). Age at transplant may be a predictor of pyelonephritis: median age of 10 patients with pyelonephritis was 4.6 years (range 0.6-19.9 years). Hydronephrotic cohort had increased rate of reflux and rejection; as not all patients underwent voiding cystourethrogram and/or allograft biopsy, this result was not significant.

CONCLUSIONS

Pediatric renal graft hydronephrosis was correlated with worsening renal function and increased incidence of pyelonephritis. More aggressive preoperative and postoperative urological testing and management should help preserve renal function.

Fetal lower urinary tract obstruction and its management

INTRODUCTION

Prenatal counselling in case of fetal obstructive uropathies still represents a clinical dilemma, despite ultrasound detection of lower urinary tract obstruction has greatly advanced during recent years as well as fetal intervention techniques.

MATERIALS AND METHODS

A systematic review of the relevant literature on the topic was performed, with a special focus on the role of antenatal ultrasound, in utero treatment and prognosis.

CONCLUSIONS

A clinico-diagnostic flow chart was developed, with the specific aim of aiding health care givers in the clinical management and the parental decision-making process.

Outcome of late presentation of posterior urethral valves in a resource-limited economy: challenges in management

Delayed presentation of patients with posterior urethral valve with complications like severe urosepsis, uremia, and anemia are seen in our setting. Renal replacement therapy which should have been offered to these patients is not readily available for children in our country. The aim of this study is to determine the pattern of late presentation and outcome of management of posterior urethral valve in a resource-limited setting. A descriptive retrospective study (1997–2009) was conducted. Data including pattern of presentation, duration of symptoms, complications, and outcome of initial management were analyzed. Twenty-one patients were seen. The median age was 3 years (2 days–13 years). The mean duration of symptoms before presentation was 2.6 years. Nineteen patients (91%) presented with urosepsis while 8 patients (36%) presented with significant renal insufficiency. Laboratory findings varied from-mild-to marked elevation in serum creatinine. Radiological findings confirmed the diagnosis of posterior urethral valve. We concluded that late presentation is common in our setting. This is associated with high morbidity and mortality rates. Efforts at improving awareness and early diagnosis among the health team should be made to stem the tide.

Adult care of children from pediatric urology

PURPOSE

In this article we highlight the difference, from established adult urology, in required approach to the care of adolescents and young adults presenting with the long-term consequences of the major congenital anomalies of the genitourinary tract. We review some abnormalities of the kidneys, progressive renal failure and disorders of bladder function from which general conclusions can be drawn.

MATERIALS AND METHODS

The published literature was reviewed and augmented with material from our institutional databases. For renal function the CAKUT (congenital abnormalities of the kidney and urinary tract) database at University College London Hospitals was used, which includes 101 young adult patients with CAKUT in whom the urinary tract has not been diverted or augmented. For bladder function some data are from patient records at Boston Children's Hospital.

RESULTS

Adolescents who grow up with the burden of a major congenital anomaly have an overwhelming desire to be normal. Many achieve high levels of education and occupy a wide range of employment scenarios. Babies born with damaged kidneys will usually experience improvement in renal function in the first 3 years of life. Approximately 50% of these cases will remain stable until puberty, after which half of them will experience deterioration. Any urologist who treats such patients needs to test for proteinuria as this is a significant indicator of such deterioration. In its absence, the urologist must have a reasonable strategy for seeking a urological cause. The most effective management for nephrological renal deterioration is with angiotensin converting enzyme inhibitors, which slow but do not prevent end stage renal failure. Renal deterioration is generally slower in these patients than in those with other forms of progressive renal disease. The bladder is damaged by obstruction or by functional abnormalities such as myelomeningocele. Every effort should be made to stabilize or reconstruct the bladder in childhood. A dysfunctional bladder is associated with or causes renal damage in utero, but continued dysfunction will cause further renal damage. Bladder function often changes in puberty, especially in boys with posterior urethral valves who may experience high pressure chronic retention. Dysfunction is managed with antimuscarinic drugs, clean intermittent self-catheterization and intestinal augmentation. Adult urologists must be able to manage the long-term problems associated with these treatments.

CONCLUSIONS

Pediatric conditions requiring management in adolescence are rare but have major, lifelong implications. Their management requires a broad knowledge of pediatric and adult urology, and could well be a specialty in its own right. Therefore, adult urologists must remain aware of the conditions, the problems that they may encounter and the special management required for these patients to live normal lives.

Matrilysin (MMP-7) inhibition of BMP-7 induced renal tubular branching morphogenesis suggests a role in the pathogenesis of human renal dysplasia

Congenital renal dysplasia (RD) is a severe form of congenital renal malformation characterized by disruption of normal renal development with cyst formation, reduced or absent nephrons, and impaired renal growth. The authors previously identified that matrilysin (matrix metalloproteinase-7) was overexpressed in a microarray gene expression analysis of human RD compared to normal control kidneys. They now find that active matrilysin gene transcription and protein synthesis occur within dysplastic tubules and epithelial cells lining cysts in human RD by RT-PCR and immunohistochemistry. Similar staining patterns were seen in obstructed kidneys of pouch opossums that show histological features similar to that of human RD. In vitro, matrilysin inhibits formation of branching structures in mIMCD-3 cells stimulated by bone morphogenetic protein-7 (BMP-7) but does not inhibit hepatocyte growth factor-stimulated branching. BMP-7 signaling is essential for normal kidney development, and overexpression of catalytically active matrilysin in human embryonic kidney 293 cells reduces endogenous BMP-7 protein levels and inhibits phosphorylation of BMP-7 SMAD signaling intermediates. These findings suggest that matrilysin expression in RD may be an injury response that disrupts normal nephrogenesis by impairing BMP-7 signaling.

CKD and bladder problems in children

Approximately 35% of children with CKD who require renal replacement therapy have a significant urological abnormality, including posterior urethral valves, a neuropathic bladder, prune belly syndrome, Hinman syndrome, or severe vesicoureteral reflux. In such children, abnormal bladder function can have a significant deleterious effect on the renal function. In children with bladder outlet obstruction, bladder compliance and capacity often are abnormal, and a sustained intravesical pressure of >40 cm H(2)O impedes drainage from the upper urinary tract. Consequently, in these conditions, regular evaluation with renal sonography, urodynamics, urine culture, and serum chemistry needs to be performed. Pediatric urological care needs to be coordinated with pediatric nephrologists. Many boys with posterior urethral valves have severe polyuria, resulting in chronic bladder overdistension, which is termed as valve bladder. In addition to behavioral modification during the day, such patients may benefit from overnight continuous bladder drainage, which has been shown to reduce hydronephrosis and stabilize or improve renal function in most cases. In children with a neuropathic bladder, detrusor-sphincter-dyssynergia is the most likely cause for upper tract deterioration due to secondary vesicoureteral reflux, hydronephrosis, and recurrent urinary tract infection (UTI). Pharmacologic bladder management and frequent intermittent catheterization are necessary. In some cases, augmentation cystoplasty is recommended; however, this procedure has many long-term risks, including UTI, metabolic acidosis, bladder calculi, spontaneous perforation, and malignancy. Nearly half of children with prune belly syndrome require renal replacement therapy. Hinman syndrome is a rare condition with severe detrusor-sphincter discoordination that results in urinary incontinence, encopresis, poor bladder emptying, and UTI, often resulting in renal impairment. Children undergoing evaluation for renal transplantation need a thorough evaluation of the lower urinary tract, mostly including a voiding cystourethrogram and urodynamic studies.

Current perspectives on congenital obstructive nephropathy

Congenital obstructive nephropathy is the leading cause of chronic renal disease in children. As a result, it represents a tremendous societal burden in terms of morbidity and mortality, as well as in health care expenses of caring for children with chronic kidney disease and end-stage renal disease. The various diagnostic, prognostic, and therapeutic challenges associated with congenital obstructive nephropathy highlight the importance of developing effective experimental models for studying this disease process. In this review, we define the clinical entity that is congenital obstructive nephropathy, outline the current standards of diagnosis and care, and discuss the utilization of current experimental models designed to help clarify some of the clinical conundrums associated with this important disease.

Pyospermia in an adult cohort with persistent lower urinary tract symptoms and a history of ablated posterior urethral valve

PURPOSE

To assess for the presence of lower urinary tract symptoms and abnormal semen parameters in adults with a history of PUV.

MATERIALS AND METHODS

The study involved 29 male patients, aged 17-51 (mean 21.5 years), with a history of PUV. Ten had more severe symptoms of frequency, urgency and enuresis, and agreed to detailed study. Medical history, urine analysis, ultrasonography and voiding cystourethrogram were completed for all. Magnetic resonance imaging of the bladder, prostate, seminal vesicles and ejaculatory ducts, ultrasonography of the prostate, as well as semen analysis and culture, and measurement of serum levels of follicle-stimulating hormone, luteinizing hormone and testosterone were performed on the 10/29 patients with severe symptoms.

RESULTS

Of the 8/10 patients who provided acceptable semen culture data, 88% (7/8) showed significant bacterial growth and pyospermia. On semen analysis, 3/8 patients had profound decreases in sperm count, 6/8 < 50% motility and 4/8 ≤ 30% normal forms. pH range for semen was 7.2-7.8 (mean 7.45). For all 10 patients, follicle-stimulating and luteinizing hormone values were within normal range. Elongation of the prostate was the only radiologic variant of the sex accessory structures.

CONCLUSION

A significant finding of pyospermia and bacterial growth in semen culture is reported in a subpopulation of young men with a history of PUV and severe lower urinary tract symptoms. This may have an impact on fertility.

Urinomas protect renal function in posterior urethral valves--a population based study

BACKGROUND/PURPOSE

Urinomas have been thought to protect renal function in boys with posterior urethral valves (PUVs), although recent reports have disputed this. This study tested the hypothesis that urinomas protect global renal function in boys with PUV.

METHODS

A retrospective analysis of all boys with PUV presenting to a tertiary unit derived from a region with an estimated population of 5.5 million was performed. Comparisons of the initial nadir creatinine, current creatinine, and renal status score (RSS) were made between those with and without urinomas. The RSS was derived from nephrology assessment of current renal status (0 = normal to 4 = end-stage renal failure or transplantation). Results were given as median (range), except for RSS, which was given as mean +/- SEM. P < or = .05 was regarded as significant.

RESULTS

During 1989-2009, 9 of 89 PUV boys were diagnosed with urinomas. Initial nadir creatinine was statistically lower in boys with urinomas (31 [18-44] vs 45 [20-574] mumol/L, P < .01). Length of follow-up was similar (5.1 [2.2-17.3] vs 5.9 [1.8-19.7] years, P = .59). Follow-up creatinine was significantly lower in urinoma boys (44 [25-77] vs 61 [29-1227] micromol/L, P < .05), as was the RSS (0.14 +/- 0.14 vs 0.91 +/- 0.14, P < .01). No urinoma boys progressed to end-stage renal failure or required transplant.

CONCLUSION

This population-based study of PUV boys demonstrates that urinomas reduce nadir creatinine and significantly protect long-term global renal function.

CONGENITAL URINARY BLADDER OUTLET OBSTRUCTION

The term congenital ‘bladder outlet obstruction (BOO)’ describes the collection of conditions in which the normal, urethral egress of urine from the fetal bladder is impaired. The term is interchangeable with fetal ‘lower urinary tract obstruction’, as used by other authors. After considering normal urinary tract embryology, we describe the epidemiology of congenital BOO and the primary anatomical disorders associated with it. We then proceed to describe its fetal and postnatal clinical manifestations and then consider therapies and interventions which have been used to manage the condition. We not only focus on urethral and bladder disease with constitutes BOO itself, but also describe associated kidney disorders which, via chronic renal excretory failure, are important causes of morbidity. Rather than provide an exhaustive review, we emphasise studies published in the last decade, and therefore readers are referred to other reviews citing numerous earlier references.

Ureter myogenesis: putting Teashirt into context

After the basic shape of the mammalian ureter is established, its epithelia mature and a coat of smooth muscle cells differentiate around nascent urothelia. The ureter actively propels tubular fluid from the renal pelvis to the bladder, and this peristalsis, which starts in the fetal period, requires coordinated smooth muscle contraction. Teashirt-3 (Tshz3) is expressed in smooth muscle cell precursors that form the wall of the forming mammalian ureter. The Teashirt gene family was first identified in Drosophila where Teashirt (Tsh) protein acts as a transcription factor directing embryonic anterior-posterior patterning and leg and eye development. In fly embryonic renal tubules, Tsh is expressed in mesodermally derived stellate cells intercalating between principal cells, and a paralogue, tiptop, is expressed in forming tubules. Teashirt is a component of several gene networks in flies and it is notable that similar networks control mammalian renal tract development. Null mutation of Tshz3 in mice leads to failure of functional muscularization in the top of the ureter and this is followed by congenital hydronephrosis. A signaling pathway can be envisaged, starting with sonic hedgehog secreted by the nascent ureteric urothelium and ending with ureteric smooth muscle cell differentiation, with Tshz3 downstream of bone morphogenetic protein 4 and upstream of myocardin and smooth muscle cell contractile protein synthesis. The phenotype of Tshz3 mutant mice resembles that of human congenital pelviureteric junction obstruction, and we suggest these individuals may have mutations of genes encoding molecules in the differentiation pathway mediated by Tshz3.

Keyhole sign: how specific is it for the diagnosis of posterior urethral valves?

OBJECTIVES

Posterior urethral valves (PUV) are the most common cause of renal impairment in boys during early childhood. Although antenatal suspicion of this pathology has become quite common in recent years, prenatal diagnosis remains challenging. The aim of this study was to evaluate the predictive value of different ultrasound criteria currently used to diagnose PUV.

METHODS

We reviewed the antenatal and postnatal files of 54 male patients referred to our center from 2000 to 2006 after detection of fetal bilateral hydronephrosis. The following ultrasound criteria were evaluated in relation to the postnatal diagnosis of PUV: amniotic fluid volume, bladder wall thickness, bladder dilatation and the presence of the 'keyhole sign'.

RESULTS

Forty-two fetuses (77.8%) were suspected to have PUV on prenatal examination. Out of these, 29 (69.0%) had PUV confirmed postnatally. The sensitivity and specificity of the antenatal diagnosis of PUV were 94% and 43%, respectively. Increased bladder wall thickness and bladder dilatation were highly associated with the diagnosis of PUV (P < 0.001). However, a thick-walled bladder was observed in 39.1% and a dilated bladder in 47.8% of the infants with a postnatal diagnosis other than PUV. The presence of the keyhole sign was not found to predict a diagnosis of PUV (P = 0.27).

CONCLUSION

In this series the use of classical prenatal ultrasound signs to diagnose PUV showed high sensitivity but low specificity. The best diagnostic indicators were increased bladder wall thickness and dilatation of the bladder. The keyhole sign was not found to be a reliable predictor of PUV.

Ca 2+ Regulation in Detrusor Smooth Muscle From Ovine Fetal Bladder After In Utero Bladder Outflow Obstruction

PURPOSE

We characterized intracellular Ca(2+) regulation in fetal bladders following outflow obstruction by examining the Ca(2+) response to agonists in smooth muscle cells.

MATERIALS AND METHODS

Severe bladder outflow obstruction was induced in male fetal sheep by placing a urethral ring and urachal ligation midway through gestation at 75 days. Fetuses were examined 30 days after surgery. Intracellular Ca(2+) in single smooth muscle cells isolated from the bladder wall was measured with epifluorescence microscopy using fura-2(AM) during exposure to agonists, such as carbachol and adenosine triphosphate, and to other activators, such as caffeine and KCl.

RESULTS

Detrusor smooth muscle cells from obstructed bladders had resting intracellular Ca(2+) similar to that in sham operated controls. The maximal response to carbachol was decreased following obstruction (p <0.05). Construction of dose-response curves also demonstrated higher EC(50) (p <0.05). However, these changes were not mirrored by caffeine evoked Ca(2+) release, which was not significantly different between the obstruction group and sham operated controls. Kinetic analysis of carbachol transients further revealed an attenuated maximal rate of increase in obstructed bladders (p <0.01). The magnitude of intracellular Ca(2+) to purinergic neurotransmitter adenosine triphosphate was also found to be smaller in cells from obstructed bladders (p <0.05), although transmembrane influx by high K depolarization was not significantly affected.

CONCLUSIONS

Muscarinic and purinergic pathways were down-regulated in fetal detrusor muscle following outflow obstruction. These major functional receptors appeared to be more susceptible to obstruction than other Ca(2+) regulators. Their impairment may contribute to the compromised contractile function seen in in utero bladder outflow obstruction.

Experimental short-term fetal bladder outflow obstruction: I. Morphology and cell biology associated with urinary flow impairment

PURPOSE

In fetal sheep, combined urethral and urachal obstruction initiated at 75 days' gestation and maintained for 30 days led to dysmorphic bladders, similar to those found in humans with prune belly syndrome, and uniformly disrupted kidney development. We aimed to create a less severe model of fetal bladder outlet obstruction, more closely resembling infants with posterior urethral valves, and additionally to further our understanding on the role of the urachus. We hypothesized that milder morphological renal tract changes would occur after shorter term experimental obstruction.

MATERIALS AND METHODS

Male fetal lambs were assigned to urachal and urethral ligation, urachal ligation only or sham operations. Analyses were performed after 9 days.

RESULTS

Concurrent urachal and urethral obstruction resulted in increased bladder weight, and protein and DNA content. Detrusor smooth muscle was well maintained, as assessed by light and electron microscopy, although urothelia showed basal apoptosis. Bladder obstruction led to hydronephrosis but failed to produce significant perturbations in urine osmolality. The nephrogenic cortex was either well preserved or was replaced by glomerular cysts; the latter group tended to have heavier bladders. Urachal obstruction alone produced similar changes suggesting that the male sheep fetal urethra is a high-resistance conduit in mid-gestation.

CONCLUSIONS

Concurrent urachal and urethral obstruction, or urachal obstruction alone, initiated in mid-gestation and maintained for 9 days leads to bladder overgrowth but preserved renal tubular function. In future, it will be interesting to determine whether bladder decompression around this stage leads to reversal of bladder overgrowth and/or ameliorates severe renal tract damage described after longer term fetal bladder outflow obstruction.

Critical and distinct roles for key RET tyrosine docking sites in renal development

Molecular mechanisms that lead to congenital anomalies of kidneys and the lower urinary tract (CAKUT) are poorly understood. To elucidate the molecular basis for signaling specificity of GDNF-mediated RET signaling in kidney development, we characterized mice that exclusively express either the human RET9 or RET51 isoform, or express these isoforms with individual mutations in docking tyrosines for PTB and SH2-domain-containing adaptors Src (Y981), PLCgamma (Y1015), and Shc (Y1062). Our results provide evidence for differential and isoform-specific roles of these docking sites in murine kidney development. Homozygous Ret(RET9) and Ret(RET51) mice were viable and show normally developed kidneys, indicating redundant roles of human RET isoforms in murine kidney development. In the context of the RET51 isoform, only mutation of the docking Tyr 1015 (Y1015F) resulted in severe renal anomalies. These included bilateral megaureters and multicystic kidneys that were caused by supernumerary ureteric buds that fail to separate from the wolffian duct as well as decreased branching morphogenesis. Similar kidney and ureter defects were observed in RET9(Y1015F) mice that contain the Y1015F mutation in the RET9 isoform. Interestingly, loss of RET9(Y1062)-mediated AKT/MAPK activation resulted in renal agenesis or kidney rudiments, whereas mutation of this residue in RET51 had no obvious effect on AKT/MAPK activity and renal development. These results reveal novel roles of key RET-dependent signaling pathways in embryonic kidney development and provide murine models and new insights into the molecular basis for CAKUT.

Implication of Wt1 in the pathogenesis of nephrogenic failure in a mouse model of retinoic acid-induced caudal regression syndrome

Renal malformations are common human birth defects that sometimes occur in the context of the caudal regression syndrome. Here, we found that exposure of pregnant mice to all-trans retinoic acid, at a time when the metanephros has yet to form, causes a failure of kidney development along with caudal regression. Maternal treatment with Am580 (retinoic acid receptor alpha agonist) also induced similar patterns of kidney maldevelopment in the fetus. In metanephroi from retinoic acid-treated pregnancies, renal mesenchyme condensed around the ureteric bud but then failed to differentiate into nephrons, instead undergoing involution by fulminant apoptosis to produce a renal agenesis phenotype. Results of whole organ cultures in serum-free medium, and also tissue recombination experiments, showed that the nephrogenic defect was intrinsic to the kidney and that it resided in the metanephric mesenchyme and not the ureteric bud. Renal mesenchyme from control embryos expressed Wilms' tumor 1 (Wt1), but this transcription factor, which is indispensable for kidney development, failed to express in metanephroi of retinoic acid-exposed embryos. Wt1 expression and organogenesis were both restored, however, when metanephroi from retinoic acid-treated pregnancies were grown in serum-containing media. Our data illuminate the pathobiology of a severe, teratogen-induced kidney malformation.

Maternal diet programs embryonic kidney gene expression

Human epidemiological data associating birth weight with adult disease suggest that organogenesis is "programmed" by maternal diet. In rats, protein restriction in pregnancy produces offspring with fewer renal glomeruli and higher systemic blood pressures than controls. We tested the hypothesis that maternal diet alters gene expression in the metanephros, the precursor of the definitive mammalian kidney. We demonstrated that maternal low-protein diet initiated when pregnancy starts and maintained to embryonic day 13, when the metanephros consists of mesenchyme surrounding a once-branched ureteric bud, is sufficient to significantly reduce glomerular numbers in offspring by about 20%. As assessed by representational difference analyses and real-time quantitative polymerase chain reactions, low-protein diet modulated gene expression in embryonic day 13 metanephroi. In particular, levels of prox-1, the ortholog of Drosophila transcription factor prospero, and cofilin-1, a regulator of the actin cytoskeleton, were reduced. During normal metanephrogenesis, prox-1 protein was first detected in mesenchymal cells around the ureteric tree and thereafter in nascent nephron epithelia, whereas cofilin-1 immunolocalized to bud derivatives and condensing mesenchyme. Previously, we reported that low-protein diets increased mesenchymal apoptosis cells when metanephrogenesis began and thereafter reduced numbers of precursor cells. Collectively, these studies prove that the maternal diet programs the embryonic kidney, altering cell turnover and gene expression at a time when nephrons and glomeruli have yet to form. The human implication is that the maternal diet ingested between conception and 5- 6-wk gestation contributes to the variation in glomerular numbers that are known to occur between healthy and hypertensive populations.

Cell Biology of Bladder Development and the Role of the Extracellular Matrix

The bladder is unique. It is the most distensible organ in the body. If the normal pattern of development is disturbed, the bladder can become dysfunctional and poorly compliant. Renal outcome is intimately linked to bladder function and hence bladder development. In this review we describe our current knowledge of the molecular processes that govern bladder development, with particular emphasis on the role of the extracellular matrix. Finally, we suggest a hypothetical model for bladder development.

A preliminary study of natural-fill radiotelemetered ovine fetal cystometry

OBJECTIVE

To determine whether fetal cystometric studies by radiotelemetry are feasible in the fetal lamb, and potentially suitable for chronically monitoring fetal bladder pressures in an experimental fetal model of bladder outlet obstruction (BOO), as in utero BOO (e.g. caused by posterior urethral valves) results in significant postnatal bladder dysfunction but the pathophysiological progression of fetal bladder maldevelopment remains poorly understood.

MATERIALS AND METHODS

The procedure required fetal sheep surgery and anaesthesia. Radiotelemetry implants comprised catheters that transmitted pressure fluctuations to an implant body; data were then transmitted using radio frequency to a receiver that passed this information to a computer. Four fetuses were used with different methods of catheter placement to optimize the technique.

RESULTS

Recordings were possible in three of the four sheep; during observation there were: (i) quiet periods with no abdominal or bladder pressure rises; (ii) synchronous activity in the bladder and abdomen; and (iii) discriminate activity, associated with intravesical activity only. Four patterns of discriminate bladder activity were observed, defined as void, immature void, staccato activity and 'unstable' type activity.

CONCLUSIONS

Radiotelemetry cystometry for long-term monitoring is feasible in the experimental fetus without causing death or morbidity, or inhibiting growth. The method can discriminate reproducible patterns of detrusor activity. Recorded 'voiding' types were consistent between experiments and as reported in other fetal animal studies.

Prenatal ultrasound guided percutaneous shunts for obstructive uropathy and thoracic disease

The authors reviewed the status of closed ultrasound-guided fetal therapy using a pigtail shunt to create vesicoamniotic or thoracoamniotic decompression of the fluid-filled space. This review includes published and textbook reports of in utero therapy for bladder obstruction, pleural effusion, and macrocystic adenomatoid malformation from 1985 through 2002. For fetuses affected by lower urinary tract obstruction, the key component is identifying those fetuses that have retained renal function and are most likely to benefit from in utero shunting. This good prognosis group has been shown to have improved survival rate and a lower incidence of renal failure. Complications of fetal loss are estimated at 5% owing to the shunt procedure, and the risk of shunt displacement varies from 30% to 50%. Hydrops secondary to primary PE has been shown to be associated with low fetal and neonatal survival at 21% to 23%. Treatment by thoracoamniotic shunting increases survival rate to 75%. The fetus with a macrocystic CCAM and secondary hydrops should be considered a candidate for thoracoamniotic shunt to decrease CCAM volume, reverse hydrops, and improve survival rate. Thoracoamniotic shunt and thoracocentesis pregnancy loss risks for pleural effusion (PE) and macrocystic adenomatoid malformation of the lung (CCAM) are 5% and 0.5% to 1.0%, respectively.

Neurotransmission and viscoelasticity in the ovine fetal bladder after in utero bladder outflow obstruction

Fetal bladder outflow obstruction, predominantly caused by posterior urethral valves, results in significant urinary tract pathology; these lesions are the commonest cause of end-stage renal failure in children, and up to 50% continue to suffer from persistent postnatal bladder dysfunction. To investigate the physiological development of the fetal bladder and the response to urinary flow impairment, we performed partial urethral obstruction and complete urachal ligation in the midgestation fetal sheep for 30 days. By electrical and pharmacological stimulation of bladder strips, we found that muscarinic, purinergic, and nitrergic mechanisms exist in the developing fetal bladder at this gestation. After bladder outflow obstruction, the fetal bladder became hypocontractile, producing less force after nerve-mediated and muscarinic stimulation with suggested denervation, and also exhibited greater atropine resistance. Furthermore, fetal bladder urothelium exerted a negative inotropic effect, partly nitric oxide mediated, that was not present after obstruction. Increased compliance, reduced elasticity, and viscoelasticity were observed in the obstructed fetal bladder, but the proportion of work performed by the elastic component (a physical parameter of extracellular matrix) remained the same. In addition to denervation, hypocontractility may result from a reduction in the elastic modulus that may prevent any extramuscular components from sustaining force produced by detrusor smooth muscle.

Urinary outflow obstruction increases apoptosis and deregulates Bcl-2 and Bax expression in the fetal ovine bladder

During organogenesis, net growth of tissues is determined by a balance between proliferation, hypertrophy, and apoptotic death. Human fetal bladder outflow obstruction is a major cause of end-stage renal failure in children and is associated with complex pathology in the kidney and lower urinary tract. Experimental manipulation of the fetal sheep urinary tract has proved informative in understanding the pathobiology of congenital obstructive uropathy. In this study we used an ovine model of fetal bladder outflow obstruction to examine effects on apoptotic cell death in the developing urinary bladder. While 30 days of obstruction in utero between 75 and 105 days gestation resulted in overall growth of the fetal bladder as assessed by weight, protein, and DNA measurements, we found that apoptosis, as assessed by in situ end-labeling, was up-regulated in fetal bladder detrusor muscle and lamina propria cells and that this was accompanied by a down-regulation of the anti-death protein Bcl-2 and an up-regulation of the pro-death protein Bax. Moreover, activated caspase-3, an effector of apoptotic death, was increased in obstructed bladders. This is the first study to define altered death in an experimental fetal model of bladder dysmorphogenesis. We speculate that enhanced apoptosis in detrusor smooth muscle cells is part of a remodeling response during compensatory hyperplasia and hypertrophy. Conversely, in the lamina propria, an imbalance between death and proliferation leads to a relative depletion of cells.

Effects of in utero bladder outflow obstruction on fetal sheep detrusor contractility, compliance and innervation

PURPOSE

Congenital bladder outflow obstruction caused by posterior urethral valves is a common cause of end stage renal failure in boys. We hypothesized that fetal bladder outflow obstruction perturbs detrusor contractility and innervation and bladder storage volume-pressure relationships.

MATERIALS AND METHODS

Severe bladder outflow obstruction was induced in male fetal sheep by placing a urethral ring and urachal ligation midway through gestation at 75 days. Fetuses were examined 30 days after surgery, when urinary tract dilatation, enlarged bladders and histologically abnormal kidneys were documented. Isolated strips of bladder detrusor from sham operated and obstructed fetuses were subjected to electrical field stimulation, carbachol, KCl and alpha-beta methylene-adenosine triphosphate. Whole bladder storage characteristics were determined by filling cystometry and bladder innervation was investigated by immunohistochemistry and Western blot.

RESULTS

Tension-frequency contractility studies showed that obstructed fetal bladder strips were significantly hypocontractile versus sham operated controls in response to electrical field stimulation and the specific agonists carbachol, KCl and alpha-beta methylene-adenosine triphosphate. Hypocontractility was greater with nerve mediated stimulation than with carbachol, suggesting relative denervation. Reduced innervation was confirmed by S100 and protein gene product 9.5 immunohistochemistry and by measuring a significant reduction in protein gene product 9.5 protein expression using Western blot. Filling cystometry showed that obstructed fetal bladders appeared more compliant (Delta V/Delta P, where Delta V is the change in volume and Delta P is the change in pressure) with larger capacity, more flaccidity and yet retained stress relaxation.

CONCLUSIONS

In response to severe experimental fetal bladder outflow obstruction the bladder becomes large and hypocontractile, and has aberrant innervation.