Predictors of eventual end stage renal disease in children with posterior urethral valves

Pre-transplant management of valve bladder: a critical literature review

OBJECTIVE

Indications, timing and problems related to augmentation cystoplasty (AC), in the context of posterior urethral valves (PUV) and renal transplantation (RT) are ill defined. Associated bladder dysfunction (BD) is not a stable condition and may cause the loss of the renal graft. Polyuria, accentuates BD and seems to improve after RT. The objective of this research is to critically review the available literature, aiming to rationalize the treatment of PUV with BD in the context of end stage renal disease (ESRD).

MATERIALS AND METHODS

A thorough literature review was performed. Pertinent papers were, critically analyzed and classified according to the level of evidence.

RESULTS

Data relating to PUV, RT and AC showed low levels of evidence. Results of RT in PUV cases with adequate management of BD were comparable to those suffering from other causes of ESRD. Bladder function can recover spontaneously after urinary undiversion. There were no established criteria to indicate AC in the context of ESRD and PUV or to define the ideal protocol to treat associated vesicoureteral reflux (VUR). Urinary tract infections (UTIs) were more frequent in transplanted PUV patients; this is possibly related to the inadequate control of BD, especially after AC. AC is feasible after RT with outcomes comparable to preemptive ones.

CONCLUSION

AC increases the risk of UTI after RT. Preemptive AC should be constructed only if the risks associated with increased bladder pressures exceed those associated with AC. Adequate management of BD is essential to improve bladder function and to minimize UTIs. AC is feasible after RT, with complication rates similar to the ones performed beforehand. Since a considerable number of PUV patients with high-pressure bladders eventually develop myogenic failure, it seems logical to postponing AC in this population, as long as they are under close surveillance.

Plasma renin activity: An early marker of progressive renal disease in posterior urethral valves

Introduction:

A significant number of children with posterior urethral valves (PUV) develop chronic renal failure (CRF) due to activation of the renin angiotensin system (RAS). We investigated the role of plasma renin activity (PRA) in these cases and sought to establish a relationship between the accepted criteria of renal damage and PRA.

Aims and Objectives:

The aim of this study is to establish the relationship between PRA and CRF.

Materials and Methods:

The records of 250 patients with PUV were reviewed. Multiple linear regression analysis was used to assess correlations between PRA, grade of reflux, presence of scars and raised creatinine and decrease in glomerular filtration rates (GFR). A P < 0.5 was considered as significant.

Results:

A total of 58 patients were included. Their mean age was 16 years, range 5.3-24.2 years, mean follow-up period was 12.6 ± 3.6 years. At diagnosis, 22/58 (38%) patients were in CRF and 36/58 (62%) patients had normal renal function (RF). The mean PRA after treatment was higher in those who developed CRF than in those with normal RF (12.6 ± 10.2 vs. 34.6 ± 14.2 ng/ml/24 h, P = 0.02). Mean GFR at 1 year of age were 48 ± 9.8 ml/min/1.73 m² and 86 ± 12.5 ml/min/1.73 m² respectively (P = 0.005). PRA correlated negatively with GFR, t = –2.816,

Confidence Interval:

P = 0. 007. In the temporal plot over a period of 14 years, a rise in PRA preceded the fall in GFR in patients who developed CRF.

Conclusions:

This study shows that RAS is activated earlier in kidneys susceptible to damage. PRA could be investigated as a marker for the early detection and prevention of ongoing renal damage.

The role of urinary TGF-β₁, TNF-α, IL-6 and microalbuminuria for monitoring therapy in posterior urethral valves

BACKGROUND

Long-term renal deterioration is common in patients with posterior urethral valves (PUV), and early identification of detrimental factors can help in counselling patients as well as in guiding future therapy. The aim of our study was (1) to evaluate urinary transforming growth factor-β1 (TGF-β1), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) levels and microalbuminuria before and after ablation of PUV and (2) to examine the effect of early induction of angiotensin-converting enzyme inhibitors (ACE-I) on renal recovery.

METHODS

The study included 30 patients with diagnosed PUV. Urinary cytokines were measured pre-operatively and post-operatively for 1 year. The study group was subdivided into two subgroups at 6 months after surgery. Group 1 included 16 patients whose urinary TGF-β1 level showed a declining trend. Group 2 included 14 patients whose urinary TGF-β1 showed a rising trend or plateaued; these patients were started on ACE-I therapy, which they received for at least 6 months.

RESULTS

Urinary TGF-β1, TNF-α and microalbumin levels were high in patients with PUV. In Group 1 patients, urinary TGF-β1, TNF-α and microalbumin levels fell significantly following valve ablation and continued to decline for 12 months. In Group 2 patients, after an initial fall following valve ablation, urinary TGF-β1, TNF-α and microalbumin showed a continued rise until 6 months post-surgery. After ACE-I therapy, there was 53.43 % fall in urinary TGF-β1, 43.15 % fall in microalbuminuria, 28.57 % improvement in split renal function and 35.80 % improvement in GFR.

CONCLUSIONS

Based on our results, urinary TGF-β1, urinary TNF-α and microalbuminuria can be used as biomarkers for the early recognition of ongoing renal damage in patients with PUV. ACE-I plays a role in retarding renal damage in these patients.

Endoscopic treatment of vesicoureteral reflux in children with posterior urethral valves

PURPOSE

We reviewed the clinical outcome of endoscopic injection therapy in children with vesicoureteral reflux persisting after posterior urethral valve ablation.

METHODS

We retrospectively reviewed the charts of 16 patients with posterior urethral valves who have undergone endoscopic injection to correct persistent reflux after successful relief of urethral obstruction. Breakthrough urinary tract infections, persistent high-grade reflux and failed ureteroneocystostomy were the indications of endoscopic antireflux surgery.

RESULTS

Reflux was grade I in 1, grade II in 3, grade III in 11 and grade IV in 4 ureters. Mean age at injection was 6.9 ± 3.8 years and the mean interval from initial intervention to injection was 4.3 ± 2.4 years. Injected material was dextranomer/hyaluronic acid in the majority (87.5 %) of cases. Reflux was resolved or downgraded in 12 ureters (63.1 %) after a single injection. All failed cases had urodynamically documented bladder dysfunction.

CONCLUSION

More than half of the patients with vesicoureteral reflux, persisting after initial valve ablation, showed complete resolution or significant downgrading in their reflux grade after endoscopic injection. Given the technical difficulties and potential complications of open surgical reimplantation in valve patients, endoscopic subureteral injection can be considered as an effective alternative to cure persistent vesicoureteral reflux.

Risk factors for renal insufficiency in children with urethral valves

Posterior urethral valves (PUV) associated with renal dysplasia are one of the most common causes of end stage kidney disease (ESKD) in childhood. In order to identify risk factors for the progression of this condition to early renal failure, we have retrospectively analyzed the clinical course, renal function, and first postnatal renal ultrasound in a sample of 42 young male patients with PUV, who were followed at a single center. Twelve (28.6%) were diagnosed with ESKD at a median age of 11.3 years. Our comparison of PUV patients without decreased estimated glomerular filtration rate (eGFR) (group A; K/DOQI CKD stage 0-1) with PUV patients showing a decreased eGFR (group B; K/DOQI CKD stage 2-5) revealed the following significant risk factors for loss of eGFR: renal volume <3rd percentile (P < 0.001), elevated echogenicity (P = 0.001), pathologic corticomedullary differentiation (P < 0.001), >3 febrile urinary tract infections (P = 0.012), and decreased eGFR at 1 year of age (P < 0.001). Receiver operating characteristic curve analysis in the cohort confirms that patients showing a renal volume >88.2 ml/m(2) body surface area (BSA) are not at risk to develop K/DOQI CKD stage 5 (sensitivity 75%, specificity 77.3%, positive/negative predictive value 37.5/94.4%). Ultrasound promises to be a valuable tool for identifying endangered patients.

Impact of posterior urethral valves on pediatric renal transplantation: a single-center comparative study of 297 cases

OBJECTIVE

  This is a retrospective long-term evaluation of the renal allografts and bladder functions in pediatric recipients who had posterior urethral valves (PUV).

PATIENTS AND METHODS

Between March 1976 and February 2009, 2033 live-donor renal transplantations were carried out in our center. Of these, 297 (14.2%) were in the pediatric age (≤18 yr). The pediatric recipients included 20 (6.7%) boys who developed end-stage renal disease as a late complication of PUV and recognized as group I while the remaining 277 pediatric recipients were defined as group II. Demographic characteristics, post-transplant complications and graft function were compared among both groups. Patient and graft survivals of both groups were also estimated. Moreover, the bladder function of the study group was evaluated by urodynamic studies.

RESULTS

Patients with PUV (group I) were significantly younger than group II. Although the overall rate of urological complications in both groups was essentially similar, the incidence of urinary fistulae and urinary tract infection were higher in group I. The mean (SD) follow up periods for group I and II were 4.7 (4.1) and 6.4 (4.8) yr, respectively. At last follow up the serum creatinine values were similar among patients of both groups. Moreover, there were no differences in graft or patient survival at five and 10 yr. Detrusor over-activity could be elicited in only one of group I patients. Schafer nomogram showed non-obstructed pattern in all cases.

CONCLUSION

Good functional outcome could be achieved for patients with PUV if renal transplantation is necessary. Pre-transplant surgical procedures may be required such as nephroureterectomy, cytoplasty or injection of refluxing ureters. A robust anti-refluxing uretero-vesical anastomosis is important, and can be achieved by a Lich-Gregoir procedure.

Posterior urethral valves: multivariate analysis of factors affecting the final renal outcome

PURPOSE

Posterior urethral valves represent the most common obstructive uropathy in children with a broad spectrum of clinical severity. We evaluated prognostic variables affecting the outcome of renal function in such children.

MATERIALS AND METHODS

Between 1987 and 2004, 120 patients with a mean age of 2 years with posterior urethral valves were treated initially with valve ablation at our center. We studied certain parameters, including age at presentation, serum creatinine (initial and nadir), initial creatinine clearance, renal ultrasound findings (hydronephrosis and renal parenchymal echogenicity), vesicoureteral reflux on initial voiding cystourethrogram, bladder dysfunction and popoff mechanisms such as the syndrome of large vesical diverticulum, urinoma and ascites. Long-term renal outcome was assessed.

RESULTS

Followup was 2 to 16 years (median 3.6). Renal insufficiency developed at the end of followup in 44 patients (36.5%). Serum creatinine at hospital admission, nadir serum creatinine, initial creatinine clearance and renal parenchymal echogenicity were significant predictors of the final renal outcome (p < 0.05). Patient age at diagnosis (2 or less vs greater than 2 years), upper tract dilatation, the presence or absence of vesicoureteral reflux, popoff mechanisms and bladder dysfunction had no significant impact on future renal function. On multivariate analysis nadir serum creatinine was the only independent prognostic factor.

CONCLUSIONS

Our data confirm the high prognostic value of nadir creatinine after primary valve ablation. Also, initial serum creatinine, creatinine clearance and renal parenchymal echogenicity on initial renal ultrasound correlate significantly with long-term renal function in children with posterior urethral valves.

A follow-up study of children with posterior urethral valve

There are not many studies on long term follow up of children following surgery for posterior urethral valve in India. This study was done to assess the growth and renal function of children who had completed five years after surgery for posterior urethral valve at our hospital. Thirty children were included in this study. They were assessed retrospectively for the age and pattern of presentation, time of surgery and outcome. Outcomes measured were stunting, renal failure (GFR, tubular functions) and bladder functions. Fifty per cent of children were symptomatic five years after surgery with enuresis, dribbling, polyuria and recurrent urinary tract infection (UTI). GFR was <60 ml/m/1.73 m(2) in 33%. Growth failure, according to the World Health Organization (WHO) definition, was present in one-third of children. A low GFR was associated with growth failure. Poor bladder function evidenced by history of dribbling and significant residual urine was seen in one-third of patients. Residual hydronephrosis was seen in 74%. The most common presenting symptoms of PUV were poor urinary stream followed by recurrent UTI, poor weight gain, renal failure and abdominal mass. Eighty per cent of the study population had undergone surgery in infancy. Five years after surgery, 50% children were symptomatic; 30% had stunting. 33% had a GFR <60 ml/m/1.73 m(2) and a significantly greater degree of stunting than those with GFR >60 ml/m/1.73 m(2). Sonologically normal kidneys on follow-up were associated with a GFR above 60 ml/m/1.73 m(2). Poor bladder function was present in 30% of the children. Univariate analysis showed that statistically significant risk factors for decline in GFR in this study are oligohydramnios and surgery beyond the neonatal period.

Prognostic value of serum creatinine levels in children with posterior urethral valves treated by primary valve ablation

PURPOSE

We evaluated the prognostic value of serum creatinine level at presentation and nadir creatinine during follow up for future renal function (RF) in children with posterior urethral valves (PUV).

MATERIALS AND METHODS

Between 1987 and 2004, 120 cases of PUV were treated initially at our hospital with valve ablation. Initial assessment included serum creatinine measurement, urine analysis and culture, renal ultrasonography and voiding cystourethrography. After valve ablation, renal ultrasound and serum creatinine measurement were repeated and thereafter during visits until the end of follow up.

RESULTS

Follow up ranged from 2 to 12 years (mean=4.4). Renal insufficiency (RI) developed at the end of follow up in 44 patients (36.5%). The mean initial and nadir serum creatinine in the RI group was higher than in the normal RF group (P<0.05). With a cut-off value of 1mg/dl for initial and nadir serum creatinine, the incidence of RI was significantly different (P<0.05).

CONCLUSION

Our data confirm the high prognostic value of nadir serum creatinine after relief of valvular obstruction. Further, the serum creatinine level before valve ablation correlates significantly with long-term RF in children with PUV.

Kidney transplantation in children with posterior urethral valves

There is controversy about the outcome of renal transplantation in patients with PUV. The objective of this study was to analyze the outcome of renal transplantation in children with PUV. Fifteen patients had a history of PUV as the etiology of their ESRD. Forty-five patients comprised a control group without lower urinary tract anomalies. Mean age and follow-up duration were not significantly different between the case and the control group (p = 0.1). The immunosuppressive protocol and the year of transplantation were similar in these two groups (p = 0.2, 0.4, respectively). Among patients with PUV, 37.5% had acute rejection; and 56.2% had chronic rejection. Among the controls, 22.2% had acute rejection and 28.8% had chronic rejection. None of these differences was significant. Mean survival time was seven yr in affected patients and 6.2 yr in the control group (p = 0.9). Among patients with PUV, the rate of graft survival in the first year after transplantation was 95%; and those in the third, fifth, and seventh yr, 91%, 65%, and 50%, respectively. For the controls, the graft survival was 83% at one yr; 80% at three yr; 71% at five yr; and 60% at seven yr after transplantation (p = 0.9). Conclusively, this study showed that a history of PUV had no effect on graft function. Graft survival was not different among these patients compared with patients free of these anomalies. We also showed that urological complications were few in these patients.

Validation of initial serum creatinine as a predictive factor for development of end stage renal disease in posterior urethral valves

OBJECTIVE

The aim of this study was to determine the value of initial serum creatinine in prediction of End-stage renal disease (ESRD) in children with posterior urethral valves PUV.

METHODS

In this retrospective study, patients diagnosed with PUV admitted in Aliasghar Children's Hospital in Tehran, Iran from 1991 through 2001 were studied. Based on the development of ESRD (need for dialysis) they were classified in two groups and their demographics, initial presentations, laboratory data, imaging findings and outcomes were reviewed and compared.

RESULTS

Thirty six male patients with PUV, treated with valve ablation (13), vesicostomy (13), or high ureterostomy (10) were followed for developing ESRD. Sixteen of the 36 patients developed ESRD at their last follow-up. There was no significant difference in age at initial presentation, presence of urinary tract infections, incidence of vesicoureteral reflux, renal dysplasia or type of primary surgical intervention between the patients with or without ESRD. Patients who progressed to ESRD had serum creatinine concentration > 1.0 mg/dl at diagnosis as compared to those without ESRD (P = 0.001).

CONCLUSION

Initial serum creatinine is a valuable factor for prediction of renal outcome in patients with PUV.

Clinical and radiological characteristics of Nigerian boys with posterior urethral valves

Posterior urethral valve (PUV) obstruction is the most common cause of bladder outlet obstruction in boys. Currently, the diagnosis of PUV is commonly made prenatally. In our environment, however, prenatal diagnosis is rare and the diagnosis is usually made postnatally from the clinical and radiological features. This study therefore examines the clinical and radiological spectrum of boys with PUV in our environment. We examined the clinical presentations, ultrasonographic and the micturating cystourethrographic (MCUG) features of boys with PUV in our institution over a 22-month period from June 2006. There were 28 patients with PUV over this period. The age at presentation ranged from 11 days to 11 years (mean age = 2.7 years). Although prenatal ultrasound scan was done in 23 (82.1%) patients, no prenatal diagnosis was made in any of the patients. The diagnosis was made after infancy in 16 (57.1%) patients. Recurrent urinary tract infection (UTI) was the most common mode of presentation occurring in 14 (50.0%) patients with 7 (50.0%) of the patients with UTI presenting with septicaemia. Voiding dysfunctions, which occurred in all the patients, were the primary mode of presentation in 12 (42.9%) patients. Three (10.7%) patients presented with renal insufficiency, which was significantly associated with the age at presentation (P = 0.026). Ultrasound scan done in the postnatal period strongly suggested the diagnosis of posterior urethral valves in 22 (78.6%) patients in whom the posterior urethra was found to be dilated, associated with thick-walled urinary bladder and bilateral hydronephrosis. Trabeculations of the bladder was a constant feature on MCUG. Other features on MCUG included dilatation of the posterior urethra in 26 (92.8%), bladder diverticuli in 15 (53.6%) and unilateral and bilateral vesicoureteric reflux in 3 (10.7%) and 1 (3.6%) patient(s), respectively. The diagnosis of PUV obstruction which is often made late in our environment, is mainly by clinical, sonographic and MCUG features in the postnatal period. A majority of patients present late, with recurrent UTI.

Posterior urethral valve: Outcome of antenatal intervention

INTRODUCTION AND AIM

Antenatal treatment of obstructive uropathy, although widely performed, remains controversial. This study evaluated the long-term outcome of managing patients with posterior urethral valves (PUV), highlighting the effect of antenatal vesicoamniotic shunt placement for patients who underwent fetal surgery.

METHODS

The medical records of 58 patients with PUV were retrospectively reviewed from June 1998 to June 2004. On the basis of prenatal assessment of sonographic findings and serial urinary electrolytes and protein measurements, patients were divided into two groups: group 1 comprised patients who had antenatal vesicoamniotic shunt placement whereas group 2 comprised patients who underwent postnatal surgical correction of PUV. Their outcomes and long-term results were evaluated.

RESULTS

Patients were followed up from 6 months to 6(1/2) years (mean 3.9 years). Group 1 included 12 patients who had vesicoamniotic shunt placement and were confirmed postnatally to have PUV. Four patients out of 12 died (33.3%); three out of the eight living patients had perinatal complications. Of the eight living patients, three (37.5%) underwent valve ablation and five (62.5%) underwent urinary diversion (three vesicostomies and two cutaneous ureterostomies). Renal function returned to normal in only four patients (50%). Radiological abnormalities (hydronephrosis and/or reflux) resolved in three (37.5%) patients, was downgraded in one (12.5%) patient and persisted in four patients (50%). Group 2 included 46 patients who were treated postnatally. Thirty-five patients (76%) underwent primary valve ablation, while 11 (24%) underwent urinary diversion (seven vesicostomies, four cutaneous ureterostomy and one pyelostomy). Renal function returned to normal in all patients who underwent valve ablation, except in three, while renal function returned to normal in only three of 11 patients who underwent urinary diversion. Radiological hydronephrosis and/or reflux resolved in 28 patients (60.9%), was downgraded in six patients (13%) and persisted in 12 patients (26.1%).

CONCLUSIONS

Antenatal vesicoamniotic shunt placement makes no difference to the outcome and long-term results of patients with PUV and debate about its efficacy on renal outcome remains. Primary valve ablation is the keystone of treatment for patients with PUV that might achieve the primary goal of nephron preservation. The lowest creatinine concentration in the first year of life is the most appropriate predictor of future renal function.

Renal transplantation in children with posterior urethral valves

The objective of this study was to analyze whether renal transplantation (RT) in children with posterior urethral valves (PUV) constitutes a special group with respect to groups with different etiologies of end-stage renal disease (ESRD). Between 1979 and 2004, 22 RT were performed in 19 children with PUV. The median age at RT was 10 years (range: 1.3-17). Immunosuppression was provided by triple therapy and polyclonal/monoclonal antibodies. This group was compared with the two control groups: (1) glomerulopathy (n=62) and (2) pyelonephritis/dysplasia (n=42) without lower urinary tract disease, transplanted in the same period. Ten graft losses occurred in 22 transplants: thrombosis (2), acute rejection (3), chronic graft nephropathy (2), and death of patients (3) with a functioning graft in the 1st postoperative month. We did not find significant differences versus the control group in renal function or probability of graft or patient survival at 1, 5, and 10 years. We observed a greater risk of urological complication in patients with PUV. RT with PUV constitutes a special group due to the compulsory young age and the need for careful and complex medicosurgical management; nevertheless, the results achieved were similar to those obtained in our general RT population.

The Role of Nutrition in Chronic Renal Insufficiency of Childhood: How Much Do We Know?

Dietary protein restriction in the treatment of symptomatic renal failure has been utilized for many years, especially as a means for reduction of 'fixed acid" load. Studies in animal models of renal failure suggest that low protein intake may retard the progression of renal disease as well. However, large, well-organized investigations into this question in humans have fallen prey to difficulties that are almost impossible to overcome. Chief among these difficulties is the problem of chronically reducing protein intake in patients with a lifelong intake far above the recommended daily allowance (RDA). Another is the fact that all previous studies have been performed in patients with moderate to severe compromise of renal function. Thus, the potential efficacy of reduced protein intake in the retardation of the progression of renal disease remains an open question. In this article, we discuss the current state of knowledge and propose an approach to answering this question.

Posterior urethral valves: preliminary observations on the significance of plasma Renin activity as a prognostic marker

PURPOSE

A significant number of children with posterior urethral valves (PUVs) have chronic renal failure due to tubulointerstitial damage. Activation of the renin-angiotensin system is known to inflict this injury. We investigated the role of plasma renin activity (PRA) in patients with PUVs and sought to establish a relationship between renal damage and PRA.

MATERIALS AND METHODS

The records of patients with PUVs were reviewed regarding the time of valve ablation, serum creatinine, scars, grade of reflux and glomerular filtration rate (GFR). PRA was measured before and after valve ablation.

RESULTS

A total of 25 patients had PUVs (mean age 3.2 +/- 2.4 years, mean period of observation 4.5 +/- 1.2 years). Mean PRA was increased before valve ablation in all patients irrespective of age, and decreased after ablation. Of 25 patients 14 (56%) had renal damage, with a mean PRA of 36 +/- 4.5 ng/ml per hour compared to 26 +/- 8.2 ng/ml per hour in patients with normal renal function (chi-square 4.2 p = 0.01). Of the 14 patients with renal damage 9 (64%) had normal GFR at age 1 year but increased PRA. Of these 14 patients the accepted criteria for renal damage of increased serum creatinine, high grade reflux, scars and decreasing GFR were present in only 6 (43%), 3 (21%), 2 (14%) and 4 (29%), respectively. PRA was increased in all 14 cases.

CONCLUSIONS

PRA was increased before valve ablation and decreased after ablation. It is increased in patients with early renal damage. Our preliminary observations indicate that PRA may be helpful in identifying patients with early renal damage.

LONG-TERM BLADDER DYSFUNCTION AND RENAL FUNCTION IN BOYS WITH POSTERIOR URETHRAL VALVES BASED ON URODYNAMIC FINDINGS

PURPOSE

Posterior urethral valves are the most common cause of congenital obstructive uropathy leading to renal failure in childhood. We investigate the influence of bladder dysfunction on renal function impairment.

MATERIALS AND METHODS

We retrospectively reviewed the records of 116 patients with posterior urethral valves. After valve ablation urodynamic studies were performed in all patients. The presence of vesicoureteral reflux (VUR), renal dysplasia, serum creatinine during followup as well as urodynamic abnormalities were recorded. Mean followup was 10.3 years after valve ablation.

RESULTS

All patients underwent endoscopic valve ablation and urinary diversion was performed in 32. Renal dysplasia was found in 9 patients. Renal function impairment at the end of followup was present in 35 patients. Urodynamic studies showed poor compliance in 30 boys, detrusor overactivity in 44, and poor compliance and detrusor overactivity in 17. Bilateral VUR was found in 17 boys at the time of diagnosis. Urodynamic studies were normal in 23 (20%) patients, of whom 4 had renal failure. Univariate analysis showed that poor compliance and detrusor overactivity had a significant correlation to renal function impairment in addition to bilateral VUR and renal dysplasia. In a multivariate analysis bilateral VUR was an independent prognostic factor for poor prognosis.

CONCLUSIONS

Bladder dysfunction may contribute to renal function impairment eventually but normal urodynamic findings do not preclude renal deterioration. It is likely that loss of compliance and detrusor overactivity would actually result in a valve bladder reaching its end point function.

Posterior urethral valves: does young age at diagnosis correlate with poor renal function?

OBJECTIVES

To determine whether young age at presentation is associated with poor renal function in patients with posterior urethral valves (PUVs). Previous studies have indicated that a young age at diagnosis is an adverse prognostic factor for patients with PUVs.

METHODS

Fifty-three children with PUVs were diagnosed between January 1998 and March 2000. The patients included 25 infants with a median age of 3 months (group 1) and 28 children with a median age of 3.5 years (group 2). No statistically significant difference was present between the two groups regarding presenting symptoms, incidence of hydronephrosis, bilateral vesicoureteral reflux, presence of popoff mechanisms, or number of positive urinary cultures at presentation. Primary valve ablation was carried out in all patients. The median follow-up period for groups 1 and 2 was 19 and 18.5 months, respectively (P <0.05).

RESULTS

The percentage of serum creatinine deviation greater than the normal age-reference range was calculated for each patient at diagnosis and at the last follow-up visit. The median percentage of serum creatinine deviation at presentation was 190% for group 1 and 22% for group 2 (P >0.05). The median percentage of serum creatinine deviation at the last follow-up visit was nil for group 1 and 10% for group 2 (P <0.009). Persistently dilated upper tracts were noted in 48% and 86% of patients in groups 1 and 2, respectively (P <0.004).

CONCLUSIONS

In contrast to the findings of previous studies, we provide evidence of a less favorable outcome with delayed presentation of PUVs relative to those diagnosed in the first year after birth in respect to renal function and upper tract dilation.

Prognostic factors for persistent distal renal tubular acidosis after surgery for posterior urethral valve

Risk factors, including age at presentation, age at surgery, time between presentation and surgery, urodynamic abnormalities, and vesicoureteric reflux, were prospectively studied for the development of distal renal tubular acidosis (DRTA) before surgery and persistent DRTA after surgery in 24 boys with posterior urethral valve (PUV) with normal serum creatinine levels. DRTA was persistent in 11 of 17 boys (65%) at the end of follow-up after intervention. For the development of DRTA before surgery, only a longer time between presentation and surgery (intervening period) turned out to be a significant risk factor on multivariate analysis (beta = -0.13; P = 0.04). Boys with persistent DRTA after surgery had older age at presentation (P = 0.03), older age at surgery (P = 0.001), a longer intervening period (P = 0.0007), and bilateral or severe unilateral reflux (P = 0.04) before surgery. On univariate logistic regression, age at surgery (beta = -0.07; P = 0.04) and intervening period (beta = -0.13; P = 0.02) were found to be significant risk factors for persistent DRTA, but on multivariate analysis, only intervening period was found to be significant (beta = -0.13; P = 0.02). A delay in intervention after noticing voiding symptoms can predict a high incidence of DRTA before intervention and persistent DRTA after surgery in boys with PUV.

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

Most children with end-stage renal failure are born with abnormal kidneys, with fetal obstructive uropathy accounting for about half these cases. Posterior urethral valves (PUV) is overwhelmingly the most common, specific diagnosis, and is confined to boys. In general, the condition is sporadic, although familial cases have been reported, perhaps suggesting that genetic factors play a role in pathogenesis. PUV can present antenatally, detected on routine fetal ultrasonography, or postnatally, when it is associated with renal failure and bladder dysfunction. Advances in postnatal surgery and medical management have reduced the mortality in PUV, but it is uncertain whether antenatal diagnosis or treatment (eg, with vesicoamniotic shunts) improves long-term renal outcome. Other disorders associated with human fetal obstructive uropathy are urethral atresia, the prune belly syndrome, and multicystic dysplastic kidney. The nephropathy associated with fetal obstructive uropathy is renal dysplasia and comprises undifferentiated and metaplastic tissues. Several studies in animals and in humans suggest that fetal urine flow impairment causes deregulation of renal precursor cell turnover and expression of growth factor/survival and transcription factor genes. Furthermore, some of these morphologic and molecular changes can be ameliorated experimentally by fetal surgical decompression or administration of specific growth factors.

Obstructive nephropathy in children: long-term progression after relief of posterior urethral valve

BACKGROUND

Approximately one third of children with end-stage renal disease have the illness because of urinary tract malformations, obstructive uropathy, and hypoplasia/dysplasia. The significant drop in infant mortality from obstructive uropathies in recent decades, attributable to prenatal diagnosis with renal ultrasonography and coordinated surgical and medical care, necessitated a reevaluation of the long-term outcome.

METHODS

To that end, we examined the long-term progression of obstructive nephropathy after neonatal relief of posterior urethral valves in our center over a span of 21 years, with diagnosis and care being provided by the same pediatric and urology team.

RESULTS

The 10 consecutive cases of posterior urethral valves represented 7% of all patients with congenital malformative uropathies seen over this period. The following procedures were performed: primary valve ablation (90%) and vesicostomy (40%). Seventy percent of patients progressed to end-stage renal disease over a (mean +/- standard error of the mean) follow-up of 11.3 +/- 2.1 years. The linear plot of the log of the inverse of serum creatinine versus time suggested unrelenting progression. The rate of progression was rapid after serum creatinine exceeded 5 mg/dL but the rate was slow and steady from serum creatinine of 1.5 to 5 mg/dL.

CONCLUSIONS

To test the effect of a therapeutic intervention to ameliorate the rate of progression, this steady and prolonged progression of 0.5 mg/dL per year between serum creatinine concentration of 1.5 to 5 mg/dL would seem the optimal study.

Delayed presentation of posterior urethral valves: a not so benign condition

PURPOSE

Posterior urethral valves are usually detected during infancy by prenatal sonography. Rarely they may be diagnosed during later childhood, adolescence or even adulthood. Less is known about presentation and outcome in these older patients. We reviewed our experience at 4 institutions with the late presentation of posterior urethral valves.

MATERIALS AND METHODS

A 13-year retrospective review revealed the late presentation of posterior urethral valves in 47 patients 5 to 35 years old (mean age 8). Data collected included presenting symptomatology, radiographic findings and renal function. Statistical analysis determined the relationships among presenting symptoms, patient age at diagnosis and renal function.

RESULTS

The most common presenting symptoms were diurnal enuresis in 60% of the cases, urinary tract infection in 40% and voiding pain in 13%. Other presenting symptoms in less than 10% of the cases included poor stream, gross hematuria and proteinuria. At diagnosis hydronephrosis and vesicoureteral reflux were present in 40 and 33% of the patients, respectively, while serum creatinine was elevated in 35% and end stage renal disease had developed in 10%. The severity of presenting signs and symptoms was significantly associated with renal impairment, while patient age at diagnosis was not.

CONCLUSIONS

Posterior urethral valves is not merely a disease of infancy. Voiding cystourethrography should be considered in boys older than 5 years who have voiding complaints, especially in association with diurnal enuresis or urinary tract infection. Patients who present late with posterior urethral valves are at risk for progression to end stage renal disease.

Posterior urethral valves: long-term renal function consequences after transplantation

PURPOSE

We assessed the long-term efficacy of renal transplantation in children with posterior urethral valves.

MATERIALS AND METHODS

We retrospectively compared the outcomes of renal transplantation in 66 children with posterior urethral valves and 116 with malformation uropathies (controls).

RESULTS

Graft survival in the posterior urethral valves and control groups was 69 and 72% at 5 years, and 54 and 50% at 10 years, respectively (not statistically significant). A statistically significant increase in serum creatinine was noted at 10 years in children with posterior urethral valves but not in controls (p < 0.05).

CONCLUSIONS

Renal transplantation in children with posterior urethral valves is not associated with a high rate of failure. However, long-term deterioration of graft function is likely related to lower urinary tract dysfunction.

Renal preservation despite 35 days of partial bladder obstruction in the fetal lamb

To determine whether the increase in renal blood flow and preservation of renal function that we demonstrated after 10 days of chronic partial bladder obstruction in the third trimester fetal lamb also occur after earlier longer obstruction, we modified our preparation and studied the effects of 35 days of obstruction begun during the second trimester. Partial bladder obstruction was created in 10 fetal lambs at 90 days of gestation (term equals 147 days). At repeat surgical intervention 28 days later vascular catheters and a left renal artery flow transducer were placed, and catheters were externalized. We then studied renal blood flow and function at gestational ages 120 days and 125 days after 30 days and 35 days of obstruction, respectively. Tissue was obtained for histology at the time of sacrifice. Eight control fetal lambs without obstruction were studied in a similar way. Bilateral hydroureteronephrosis was noted in all fetal lambs after partial obstruction, whereas the kidneys and bladders of the control animals had a normal appearance. Renal blood flow was higher in the obstructed fetal lambs than in controls (20.2 +/- 4.9 versus 10.2 +/- 0.9 ml. per minute per kg., p < 0.05 after 30 days and 17.1 +/- 2.7 versus 9.7 +/- 0.9 per minute per kg., p < 0.05 after 35 days). There was no evidence of decreased renal function by any parameter and, in fact, glomerular filtration rate and urine volume were increased after 30 days of obstruction (1.59 +/- 0.32 versus 0.69 +/- 0.07 ml. per minute per kg., p < 0.05 and 15.7 +/- 4.3 versus 5.2 +/- 0.8 ml. per hour per kg., p < 0.05, respectively). Histological studies demonstrated normal architecture of the kidneys but thinned cortex. We conclude that the physiological responses of the fetus are such that partial lower urinary tract obstruction in our preparation results in a prolonged increase in renal blood flow and preservation of renal function.

Prenatally detected posterior urethral valves: is gestational age at detection a predictor of outcome?

Between 1982 and 1992, 67 boys with posterior urethral valves were managed at our hospital, including 32 (48%) in whom the condition was detected prenatally. We examined the relationship between gestational age at detection and outcome at a median followup of 3.9 years (range 4 months to 10 years). Detection at or before 24 weeks of gestation predicted a poor outcome with 9 of 17 patients (53%) dead or in chronic renal failure at followup. Of the cases detected later in pregnancy only 1 had a poor outcome (p = 0.01). All of the cases detected after 24 weeks of gestation had had normal second trimester scans. Growth parameters for boys in the early and late detection groups were not statistically different. However, there was a significant association between renal failure and growth with 67% versus 14% having heights less than the 3rd percentile (p = 0.05). Respiratory distress at birth predicted a poor outcome, while the presence of palpable abdominal abnormalities or vesicoureteral reflux failed to predict outcome.

Posterior urethral valves. Does prenatal diagnosis influence prognosis?

Forty-eight boys with posterior urethral valves were reviewed to assess the impact on prognosis of prenatal ultrasonography, which had been the method of diagnosis in 17 of them; the remaining 31 presented postnatally. Renal function before treatment was mildly to moderately impaired in 59% of those presenting prenatally, 42% presenting before 3 months of age and 25% of those first presenting when older than 3 months. All but one of the infants diagnosed prenatally had clinical signs and/or elevated serum creatinine in the early neonatal period. Eight had associated maternal oligohydramnios, of whom 6 presented prenatally and 2 postnatally: this factor was associated with a poor prognosis, with renal impairment persisting in 6 of these patients after treatment. Renal function did not relate consistently to the presence or otherwise of vesicoureteric reflux (unilateral or bilateral). Twelve of the patients who presented postnatally had normal fetal ultrasonography late in pregnancy, of whom 11 had upper tract dilatation when investigated. Six of these patients who currently have impaired renal function did not have maternal oligohydramnios, and it is argued that antenatal detection of the condition would have been beneficial in less than 20% of patients presenting postnatally with posterior urethral valves.

Results of renal transplantation in boys treated for posterior urethral valves

The results of renal transplantation in boys treated for posterior urethral valves were evaluated and compared with a matched control group. Patient and graft survival was equal in both groups, although serum creatinine levels were slightly higher in the posterior urethral valves group. Postoperative complications, such as urinary tract infections, occurred more frequently in the posterior urethral valves group. Urodynamic evaluation was performed before transplantation in 11 of 20 patients. Adequate treatment of bladder dysfunction, such as poor compliance and/or hyperreflexia, is essential in diminishing the risks of secondary graft damage due to severe bladder dysfunction.

Prognosis for patients with prenatally diagnosed posterior urethral valves

Children in whom posterior urethral valves are diagnosed shortly after birth are at higher risk for renal failure than children in whom posterior urethral valves are diagnosed later in life. The influence of prenatal diagnosis of posterior urethral valves on clinical outcome has not been established. We collected data on children with posterior urethral valves treated since birth at our hospital between 1975 and 1990. The clinical outcomes for 8 patients diagnosed prenatally and 15 diagnosed neonatally were compared. Of the 8 patients in the prenatal group 5 (64%) had renal failure compared to 5 of 15 (33%) in the neonatal group (p greater than 0.05). Nadir creatinine of more than 1.2 mg./dl. correlated with the development of renal failure in all patients in the neonatal and prenatal groups. There was 1 death in the prenatal group. In our experience prenatal diagnosis of posterior urethral valves has grave implications, including a 64% incidence of progressive renal failure and a 64% incidence of transient pulmonary failure. Oligohydramnios and postnatal pulmonary insufficiency are predictive of progressive renal failure. Earlier diagnosis and treatment of children with posterior urethral valves did not improve the clinical prognosis.

The predictive value of ultrasonography in evaluation of infants with posterior urethral valves

Between 1981 and 1989, 28 infants less than 6 months old with posterior urethral valves underwent ultrasound evaluation as part of the initial evaluation at our hospital. The single ultrasound feature that correlated with subsequent renal function was the status of corticomedullary differentiation. The presence of corticomedullary junctions in at least 1 kidney in 17 infants was always associated with a serum creatinine level of 0.8 mg./dl. or less in long-term followup. Of 11 patients with absent corticomedullary differentiation 7 had eventual creatinine levels of greater than 0.8 mg./dl. with 5 of them suffering clinically significant renal insufficiency. An association between vesicoureteral reflux and absent corticomedullary junctions was also found.

Renal transplantation in children with posterior urethral valves

We compared retrospectively the outcome of renal transplantation in 18 children with a diagnosis of posterior urethral valves to 18 matched children with nonobstructed renal failure to identify the disadvantages of renal transplantation into the valve bladder. There was no statistical difference in patient survival. The 5-year graft survival rate was 62.3% in children with posterior urethral valves and 48% in the control group. The difference was not statistically significant (p = 0.32). A statistically significant increase in serum creatinine from 1.2 to 2.2 mg./dl. was noted in the patients with posterior urethral valves, which was not seen in the control group (p = 0.0009). The clinical significance of this finding is unknown. Renal transplantation can be performed successfully in patients with posterior urethral valves. A prospective study is required to determine the benefits of preoperative lower urinary tract urodynamic assessment and the true effect of the valve bladder.