Detrusor hypocontractility in children with posterior urethral valves arises before puberty

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

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

Antenatal and postnatal management of posterior urethral valves: where do we stand?

Introduction

Posterior urethral valve (PUV) is the leading etiology of lower urinary tract obstruction (LUTO) in boys and is an important cause of end-stage renal disease (ESRD) in children. The aim of this article is to review the current status on antenatal intervention for PUV as well as postnatal medical and surgical management.

Main body

MEDLINE, EMBASE, Pubmed and Google Scholar search was conducted throughout December 2020 using the keywords: posterior urethral valves, congenital urinary obstruction, antenatal, valve bladder syndrome, medical, anticholinergics, alpha blocker, antibiotics, biofeedback, diversion, augmentation cystoplasty and renal transplantation. Only papers written in English were included. The relevant literature was summarized. Despite advances in antenatal intervention for fetal LUTO, it remains associated with considerable fetal and maternal morbidity. Patient selection criteria for antenatal intervention are greatly debated. Fetal intervention has resulted in improved perinatal survival in properly selected cases, with a questionable benefit to postnatal renal function. There is decent evidence supporting the use of anticholinergics in infants and young children following valve ablation, with less robust evidence advocating alpha blockers, overnight catheter drainage and biofeedback. The role of urinary diversion remains contentious. Optimizing bladder dynamics is crucial for successful renal transplantation outcomes.

Conclusion

While antenatal intervention has failed to improve renal function outcomes of PUV, patient-centered medical and sometimes surgical interventions can help delay the progression of chronic kidney disease. Lifelong monitoring and management of the associated bladder dysfunction is indispensable even after successful renal transplantation.

Urodynamics in Posterior Urethral Valve: Pursuit of prognostication or optimisation

INTRODUCTION

Detrusor dysfunction is known to persist in several patients of Posterior Urethral Valve (PUV) after successful fulguration leading to progressive deterioration of renal function. Persistent bladder outlet obstruction (BOO) in the form of bladder neck hypertrophy, residual valves or strictures may contribute to progressive detrusor dysfunction. These are assessed radiologically or cystoscopically and are managed variedly by anticholinergics, alpha-adrenergic blockers or even bladder neck incision. Unfortunately, currently we do not have any objective measures to evaluate the degree of BOO in children or follow treatment outcome of any such measures.

OBJECTIVE

To assess the feasibility of pressure flow studies in children and proposition of an age independent index to quantify outflow parameters.

STUDY DESIGN

We retrospectively studied the urodynamic data of the follow up cases of PUV who had been referred to us for urodynamic evaluation. Free flow uroflowmetries and filling and voiding cystometrogram were performed as per recommended protocol. Parameters like Adjusted Bladder Capacity (ABC = Voided volume + post void residue; expressed as percentage of expected bladder capacity {EBC}), overactivity, compliance, Qmax and P _{det at Qmax} were taken into consideration. Indices like Bladder Outlet Obstruction Index (BOOI) and Bladder Contractility Index (BCI) were calculated. Multivariate analysis was run to assess correlation of ABC with other parameters. Receiver Operating Characteristics (ROC) curve analysis was performed to assess predictive values of BOOI for ABC.

RESULTS

We did not find the ABC to change with age as has been classically described. Qmax and BCI were found to correlate with age. Values obtained for P _{det at Qmax} and BOOI were not dependent on age and were in similar range as observed in adults. On multivariate analysis, small bladder was found to positively correlate with presence of overactivity, high BOOI and low BCI. ROC curve analysis showed a BOOI >29 could predict ABC to be <100% EBC with moderate sensitivity and specificity.

DISCUSSION

Pressure flow studies are the only objective means of quantifying outlet resistance, hitherto they have been considered to be unrepresentative in children. Documentation and correction of high outflow pressures may arrest the cycle of detrusor hypertrophy and dysfunction.

CONCLUSION

Quality pressure flow studies are feasible in children. Values of P _{det at Qmax} and BOOI in children are age independent and similar to those observed in adults. BOOI can be potentially used in children to assess degree of BOO.

Challenges in pediatric urologic practice: a lifelong view

The role of the pediatric urologic surgeon does not end with initial reconstructive surgery. Many of the congenital anomalies encountered require multiple staged operations while others may not involve further surgery but require a life-long follow-up and often revisions. Management of most of these disorders must extend into and through adolescence before transitioning these patients to adult colleagues. The primary goal of management of all congenital uropathies is protection and/or reversal of renal insult. For posterior urethral valves, in particular, avoidance of end-stage renal failure may not be possible in severe cases due to the congenital nephropathy but usually can be prolonged. Likewise, prevention or minimization of urinary tract infections is important for overall health and eventual renal function. Attainment of urinary continence is an important goal for most with a proven positive impact on quality of life; however, measures to achieve that goal can require significant efforts for those with neuropathic bladder dysfunction, obstructive uropathies, and bladder exstrophy. A particular challenge is maximizing future self-esteem, sexual function, and reproductive potential for those with genital anomalies such as hypospadias, the bladder exstrophy epispadias complex, prune belly syndrome, and Mullerian anomalies. Few endeavors are rewarding as working with children and their families throughout childhood and adolescence to help them attain these goals, and modern advances have enhanced our ability to get them to adulthood in better physical and mental health than ever before.

Posterior urethral valve: Prognostic factors and renal outcome

OBJECTIVE

The aim was to study the outcome of posterior urethral valve (PUV) cases treated by stepladder protocol and the prognostic factors affecting the outcome.

MATERIALS AND METHODS

Hospital records of all PUV patients treated by stepladder protocol between January 1992 and December 2013 were reviewed. The studied parameters were: Age at presentation, serum creatinine, types of surgical intervention, vesicoureteral reflux (VUR) on initial voiding cystourethrogram (VCUG), renal cortical scars, plasma renin activity (PRA), and glomerular filtration rate (GFR).

RESULTS

Of 396 PUV patients treated during the study period, 152 satisfied study criteria. The age at presentation ranged from 2 days to 15 years (mean 31.3 months). The mean follow-up period was 5 years (range: 2-18 years). Primary endoscopic valve ablation was the most common initial procedure. Chronic renal failure was seen in 42.7% patients at the last follow-up. Serum creatinine at presentation, initial PRA levels, initial GFR, and PRA levels at last follow-up were significant predictors of final renal outcome. Age at presentation (<1 vs. >1 year), presence/absence of VUR on initial VCUG and renal cortical scars had no significant correlation with ultimate renal function.

CONCLUSION

Our study confirms the high prognostic significance of initial serum creatinine, PRA levels and GFR in cases with PUV. PRA also holds promise in long-term follow-up of these patients as a marker of progressive renal damage.

Efficacy and safety of urethral de-obstruction in boys with overactive bladder complaints

OBJECTIVE

To gain insight into the efficacy and safety of urethral de-obstruction in boys with overactive bladder (OAB) complaints refractory to conservative treatment.

MATERIALS AND METHODS

All boys, older than 5 years, referred in 2009 for OAB complaints were included, n = 180. Nine had abdominal or penile pain as predominant complaint. 82% were tertiary referrals after unsuccessful conservative treatment with antimuscarinic medication and/or urotherapy for OAB. In 121, urethral obstruction was urodynamically proven or seriously suspected, and they underwent urethrocystoscopy with relief of obstruction, when present. Average duration of unsuccessful conservative pre-treatment in this group of patients was 1.2 years. Postoperative results, in terms of relief of complaints, were analyzed. Safety was assessed by analyzing those patients who had a secondary transurethral procedure in the same year, or in the 3 years after primary treatment.

RESULTS

Of 106 boys with OAB, urge incontinence or therapy-resistant bedwetting, after de-obstruction 33 became free of complaints and 39 showed significant improvement, totaling 72 (68%); dry after additional urotherapy 11 (10%); no change 21 (20%). Nine boys had de-obstruction because of penile or abdominal pain, with 5 completely cured after the procedure. Follow-up treatment was cognitive training in 39, temporary anticholinergic treatment in 26 and CIC in 2 cases. Recurrence of obstruction was seen in 10% during the 3-year follow-up period.

CONCLUSION

After failure of conservative therapy, one should actively look for any urethral obstruction as underlying cause of OAB. For such patients, urethral de-obstruction is highly effective, with only a few minor late complications resulting in recurrence of obstruction.

A systematic review on renal and bladder dysfunction after endoscopic treatment of infravesical obstruction in boys

Background

Posterior urethral valves (PUV) may cause subtle to severe obstruction of the urethra, resulting in a broad clinical spectrum. PUV are the most common cause of chronic renal disease in boys. Our purpose was to report the incidences of kidney and bladder dysfunction in boys treated with endoscopic valve resection for PUV.

Methodology

We searched MEDLINE and EMBASE databases until 1st of July 2011, to identify original papers that described outcome of endoscopic valve resection (EVR) in boys. We extracted information on (1) patient characteristics and clinical presentation of PUV related to outcomes and (2) the post-treatment absolute risks for kidney and bladder dysfunction.

Principal findings

Thirty-four studies describing renal function, vesicoureteral reflux (VUR), incontinence, and urodynamic bladder function after EVR in 1474 patients were retrieved. Patients treated for PUV show high percentages of chronic kidney disease (CKD) or end stage renal disease (ESRD), 22% (0–32%) and 11% (0–20%), respectively. Elevated nadir serum creatinine was the only independent factor associated with renal failure. Before treatment, VUR was present in 43% of boys and after EVR, VUR was present in 22%. Post treatment, 19% (0–70%) was reported to suffer from urinary incontinence. Urodynamic bladder dysfunction was seen in many patients (55%, 0–72%) after treatment of PUV.

Conclusions

The reported cumulative incidence of renal and bladder dysfunction in patients with PUV after endoscopic PUV treatment varies widely. This may reflect a broad clinical spectrum, which relates to the lack of a standardised quantification of obstruction and its severity. Moreover, the risk of bias is rather high, and therefore we put little confidence in the reported estimates of effect. We found elevated nadir serum creatinine as a predictor for renal dysfunction. In order to be able to predict outcomes for patients with PUV, an objective classification of severity of obstruction is mandatory.

Long-term bladder function followup in boys with posterior urethral valves: comparison of noninvasive vs invasive urodynamic studies

PURPOSE

We studied whether noninvasive urodynamic evaluation can be as effective and safe as invasive urodynamics in detecting lower urinary tract dysfunction and in preventing late onset renal failure during long-term management of boys with posterior urethral valves.

MATERIALS AND METHODS

We evaluated 47 boys with posterior urethral valves using repeat urodynamics. A total of 28 patients with followup of at least 3 years and repeat evaluation of serum creatinine were included in the study. The first 14 boys in the series underwent cystometry and pressure-flow study at least every 3 years (group A), and the remaining 14 patients were monitored annually from age 5 with bladder diary, uroflowmetry, post-void residual urine on ultrasound and serum creatinine (group B). Lower urinary tract dysfunction and serum creatinine were compared (Fisher exact test and Mann-Whitney test) between groups A and B, and by stratifying patients into subgroups by age (5 to 6, 7 to 13 and older than 13 years). In all patients urodynamic diagnosis of lower urinary tract dysfunction was matched and confirmed with lower urinary tract symptoms.

RESULTS

During followup the prevalence of lower urinary tract dysfunction did not differ significantly between group A (71% in boys 5 to 6, 43% in boys 7 to 13 and 85% in boys older than 13 years) and group B (36%, 43% and 60%, respectively). Late onset renal failure was observed in 2 boys in group A and 2 in group B.

CONCLUSIONS

Noninvasive urodynamic evaluation seems to be as safe and effective as invasive urodynamic study in the long-term management of boys with posterior urethral valves. Based on these findings, invasive urodynamics may be reserved for cases of progressive deterioration of lower urinary tract dysfunction or renal function.

Radiotelemetered urodynamics of obstructed ovine fetal bladders: correlations with ex vivo cystometry and renal histopathology

OBJECTIVE

To test the hypothesis that fetal bladder outlet obstruction (BOO) in sheep causes abnormal urodynamics correlating with the initiation of renal pathology, as most boys with posterior urethral valves (PUV) have bladder dysfunction when assessed after birth.

MATERIALS AND METHODS

Male ovine fetuses at 94 days of gestation were assigned to BOO (four) or sham control (five) groups. In BOO fetuses, radiotelemetry catheters were inserted transurachally and intraperitoneally, and the urethra was partly occluded. In two sham controls catheters were inserted directly through the bladder wall; the remaining three had sham surgery only. Radiotelemetered cystometry was recorded daily where possible. At the end of the experiment (9 days), ex vivo cystometry, bladder contractility studies and renal tract histology were assessed.

RESULTS

Ultrasonography showed dilated renal tracts only in BOO fetuses; three of four BOO fetuses had renal cortical cysts. The control fetuses with bladder catheters died in utero, so urodynamics were recorded only in fetuses with BOO. The baseline filling/storage detrusor pressures increased slightly (by a mean of 5 mmHg) during the first 4 days of BOO, thereafter returning to those at the outset. There were marked changes in the patterns of bladder activity from 1 to 9 days. The frequency and duration of 'voiding' increased; as such the higher sustained pressures of emptying activity were progressively extended and the periods of low pressure filling/storage accordingly shortened. The patterns among individual fetuses with BOO were not substantially different, except that the one with the non-cystic kidneys had a more moderate frequency and duration of voiding. Ex vivo compliance and contractility showed no consistent differences in detrusor compliance or contractility between BOO and sham bladders.

CONCLUSION

In this fetal model of PUV, there was a progressive increase in the duration and frequency of sustained elevated 'voiding' pressures, with no change in bladder compliance. Fetal kidneys were sensitive to these altered dynamics, with the formation of cortical cysts by 9 days after initiating BOO.

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.

Myogenic bladder decompensation in boys with a history of posterior urethral valves is caused by secondary bladder neck obstruction?

OBJECTIVE

To investigate whether myogenic bladder decompensation in patients treated for congenital posterior urethral valves (PUV, the most serious cause of infravesical obstruction in male neonates and infants) may be secondary to bladder neck obstruction, as despite prompt ablation of PUV these patients can have dysfunctional voiding during later childhood or adolescence, the so-called 'valve bladder syndrome'.

PATIENTS AND METHODS

The study comprised 18 boys (mean age 14 years, range 6.2-18.5) who had had successful transurethral ablation of PUV between 1982 and 1996, and had completed a follow-up which included serial assessment of serum creatinine, completion of a standard voiding diary, ultrasonography with measurement of urine before and after voiding, a urodynamic examination with simultaneous multichannel recording of pressure, volume and flow relationships during the filling and voiding phases, coupled with video-cystoscopy at least twice. The mean (range) follow-up was 9.3 (6-17) years.

RESULTS

Urodynamic investigation showed myogenic failure with inadequate bladder emptying in 10 patients; five with myogenic failure also had unstable bladder contractions. On video-cystoscopy the posterior bladder neck lip appeared elevated in all patients but in those with myogenic failure it was strongly suggestive of hypertrophy, with evidence of obstruction. At the last follow-up one patient with myogenic failure who had had bladder neck incision and four others who were being treated with alpha-adrenergic antagonists had a significant reduction of their postvoid residual urine.

CONCLUSION

Despite early valve ablation, a large proportion of boys treated for PUV have gradual detrusor decompensation, which may be caused by secondary bladder neck obstruction leading to obstructive voiding and finally detrusor failure. Surgical or pharmacological intervention to improve bladder neck obstruction may possibly avert this course, but further studies are needed to validate this hypothesis.

Initial and long-term management of posterior urethral valves

Posterior urethral valves are the most common cause of congenital obstructive uropathy, resulting in renal failure in childhood. Nowadays, in most cases, diagnosis is suggested by antenatal ultrasound. However, antenatal intervention has not resulted in a significantly improved outcome. Endoscopic valve ablation is the initial treatment in most of these neonates, but others procedures, like vesicostomy or ureterostomy, can also be justified in some particular cases in order to improve renal function prognosis. Different factors like bladder dysfunction, VUR, polyuria and proteinuria, can be responsible for the slow and progressive deterioration in renal function that some of these patients show over the years. By treating them all, we may prevent or delay the onset of end stage renal disease.

Does Treatment With Clean Intermittent Catheterization in Boys With Posterior Urethral Valves Affect Bladder and Renal Function?

PURPOSE

In boys with resected posterior urethral valves (PUV) deterioration of renal function is seen during childhood and adolescence, which may partly be caused by bladder dysfunction. We present data on renal and bladder function initially and at followup of boys with PUV in whom the bladder dysfunction has been treated since infancy.

MATERIALS AND METHODS

The study included 35 boys with PUV. Bladder regimen, including early toilet training from the age of 1.5 years and detrusor relaxant drugs for the treatment of incontinence from ages 4 to 6 years, was introduced to all patients. A total of 19 boys were started on clean intermittent catheterization (CIC) at a median age of 8 months due to pronounced bladder dysfunction with poor emptying, unsafe pressure levels, high grade reflux and renal impairment.

RESULTS

No serious complications of CIC have been seen during followup. Of the 19 boys 2 stopped performing CIC due to noncompliance of the parents at 1 and 3 years, respectively. Initial renal function, measured as median glomerular filtration rate (GFR) in percent of expected for age, was 60% in the CIC group and 90% in the nonCIC group. At followup at a median age of 8 years the CIC group (n = 14, 3 transplanted boys excluded) had an increase in median differential GFR (difference between followup and initial GFR) of 7% (p <0.01), which was similar increase to that of the nonCIC group. In the 2 boys who stopped performing CIC renal function deteriorated with a median differential GFR of -24%. In the CIC group detrusor instability decreased. Poor compliance was seen in 6 of the 19 boys initially and only one remained poorly compliant. In 1 of the boys who stopped performing catheterization a low compliant bladder developed. In all of the other cases bladder capacity increased more than expected for age.

CONCLUSIONS

The results suggest that treatment of bladder dysfunction in boys with PUV can counteract the deterioration in renal function seen during childhood but the number of patients in our study is limited.

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.

The valve bladder: etiology and outcome

The infravesical obstruction created by posterior urethral valves produces a series of structural, biochemical, and functional changes in these boys' bladders that begins during fetal life. Any change can be irreversible and result in the alterations in bladder function that can be found in some of these patients. Bladder instability, poor compliance, and myogenic failure are the three most common urodynamic patterns and are also responsible for some of these patients' poor long-term prognosis. Treatment of bladder dysfunction in these patients is basically directed toward improving their kidney function prognosis and also to avoid the urinary incontinence presented secondarily by some valve bladders.

The valve bladder syndrome: pathophysiology and treatment with nocturnal bladder emptying

PURPOSE

We determine the etiology and treat the specific pathophysiology of the valve bladder syndrome.

MATERIALS AND METHODS

Defined as persisting or progressive severe hydroureteronephrosis without residual or recurrent obstruction, the valve bladder syndrome developed in 18 boys who underwent successful ablation of the posterior urethral valve. Serial radiographic, renal function, renographic, urodynamic and perfusion studies were performed for a mean time of 11 years.

RESULTS

The cause of the valve bladder syndrome proved to be sustained bladder over distention due to a combination of polyuria with 24-hour urine volume greater than 2 l. in 10 boys, impaired bladder sensation in 18 and residual urine volume in 14. Treatment of over distention during the daytime alone was unsuccessful. Nocturnal bladder emptying was performed with an indwelling nighttime catheter, intermittent nocturnal catheterization and/or frequent nocturnal double voiding. Hydronephrosis markedly improved once nocturnal bladder emptying was started and was comparable to the results after urinary diversion.

CONCLUSIONS

The valve bladder syndrome is not due to a permanent prenatal alteration in bladder anatomy and function. Instead, it appears to result from sustained postnatal bladder over distention due to a combination of polyuria, impaired bladder sensation and residual urine volume, which represent sequelae of prenatal valve injury. These factors synergize to prevent bladder normalization after valve ablation and progressively reduce functional bladder capacity to maintain bladder over distention. Bladder decompensation, upper tract dilation, and renal injury develop and characterize the valve bladder syndrome. Because current therapy, including intermittent catheterization, leaves the bladder full throughout the night, it remains markedly over distended. Nocturnal bladder emptying is the specific antidote for this pathophysiological situation, and results in prompt and impressive improvement or elimination of hydronephrosis in these and similar groups of patients. This response to nocturnal bladder emptying suggests that the bladder is not the primary cause for the valve bladder syndrome.

Detrusor hypocontractility evolution in boys with posterior urethral valves detected by pressure flow analysis

PURPOSE

We evaluated the natural evolution of detrusor voiding contractility in boys who underwent posterior urethral valve ablation using pressure flow analysis, which is a mathematical computerized analysis of pressure flow studies.

MATERIALS AND METHODS

Among 30 boys with posterior urethral valves who were being prospectively followed, even if asymptomatic on serial pressure flow studies, 11 were included in our study. These 11 patients had had at least 2 evaluations performed between ages 5 and 15 years, a minimum interval of 4 years between the first and last examination, and all pressure flow studies records available for mathematical analysis of voiding contractility. The first examination had been done at ages 5 to 10 years (average 7 +/- 2.04) and the last one at ages 9 to 15 (12.5 +/- 2.5), including 6 evaluated after puberty. All but 1 patient underwent valve endoscopic resection as a newborn and none received urinary diversion. Voiding symptoms, post-void residual, cystometric bladder capacity and bladder instability were considered. Voiding phase maximal detrusor pressure and flow rate were evaluated and detrusor contractility was calculated by the pressure flow analysis parameters of contraction velocity, detrusor contractile power expressed as watt factor and Schafer's nomogram. Contraction velocity and contractile power factor were considered low if below 2 standard deviations of previously determined normal values. True hypocontractility was diagnosed when at least 2 pressure flow analysis parameters were low.

RESULTS

True hypocontractility was detected in 3 of the 11 boys at the first examination and in 8 at the last pressure flow analysis. The remaining 8 and 3 cases of first and last examinations, respectively, were considered to have normal contractility even if 4 of the 8 and 1 of the 3 had 1 low pressure flow analysis parameter (covert hypocontractility). Detrusor contractility worsened in 6 patients, hypocontractility was detected at the first pressure flow analysis in 2, hypocontractility changed to normal in 1 and pressure flow analysis remained normal in 2. Of the 6 boys followed through puberty 5 had hypocontractility, including 3 with cystometric bladder capacity greater than 700 ml., high post-void residual and strained voiding. Of the 11 patients 8 had detrusor instability, including 7 with urge symptoms, at first evaluation which was not found at last examination.

CONCLUSIONS

Pressure flow analysis extensively used in men has been confirmed as a useful tool to assess voiding contractility in children. The majority of boys with posterior urethral valves have progressive impairment of detrusor contractility at voiding many years after relief of obstruction. The pattern of hypocontractility, which is detected early on pressure flow analysis, follows a prolonged phase of instability in many cases and leads to an over distended bladder in most patients followed after puberty. Questions arise if this evolution may be prevented by early (pharmacological or rehabilitative) treatment and if it is partially determined by extensive use of drugs acting against unstable detrusor contractions.

DETRUSOR HYPOCONTRACTILITY EVOLUTION IN BOYS WITH POSTERIOR URETHRAL VALVES DETECTED BY PRESSURE FLOW ANALYSIS

PURPOSE

We evaluated the natural evolution of detrusor voiding contractility in boys who underwent posterior urethral valve ablation using pressure flow analysis, which is a mathematical computerized analysis of pressure flow studies.

MATERIALS AND METHODS

Among 30 boys with posterior urethral valves who were being prospectively followed, even if asymptomatic on serial pressure flow studies, 11 were included in our study. These 11 patients had had at least 2 evaluations performed between ages 5 and 15 years, a minimum interval of 4 years between the first and last examination, and all pressure flow studies records available for mathematical analysis of voiding contractility. The first examination had been done at ages 5 to 10 years (average 7 +/- 2.04) and the last one at ages 9 to 15 (12.5 +/- 2.5), including 6 evaluated after puberty. All but 1 patient underwent valve endoscopic resection as a newborn and none received urinary diversion. Voiding symptoms, post-void residual, cystometric bladder capacity and bladder instability were considered. Voiding phase maximal detrusor pressure and flow rate were evaluated and detrusor contractility was calculated by the pressure flow analysis parameters of contraction velocity, detrusor contractile power expressed as watt factor and Schafer's nomogram. Contraction velocity and contractile power factor were considered low if below 2 standard deviations of previously determined normal values. True hypocontractility was diagnosed when at least 2 pressure flow analysis parameters were low.

RESULTS

True hypocontractility was detected in 3 of the 11 boys at the first examination and in 8 at the last pressure flow analysis. The remaining 8 and 3 cases of first and last examinations, respectively, were considered to have normal contractility even if 4 of the 8 and 1 of the 3 had 1 low pressure flow analysis parameter (covert hypocontractility). Detrusor contractility worsened in 6 patients, hypocontractility was detected at the first pressure flow analysis in 2, hypocontractility changed to normal in 1 and pressure flow analysis remained normal in 2. Of the 6 boys followed through puberty 5 had hypocontractility, including 3 with cystometric bladder capacity greater than 700 ml., high post-void residual and strained voiding. Of the 11 patients 8 had detrusor instability, including 7 with urge symptoms, at first evaluation which was not found at last examination.

CONCLUSIONS

Pressure flow analysis extensively used in men has been confirmed as a useful tool to assess voiding contractility in children. The majority of boys with posterior urethral valves have progressive impairment of detrusor contractility at voiding many years after relief of obstruction. The pattern of hypocontractility, which is detected early on pressure flow analysis, follows a prolonged phase of instability in many cases and leads to an over distended bladder in most patients followed after puberty. Questions arise if this evolution may be prevented by early (pharmacological or rehabilitative) treatment and if it is partially determined by extensive use of drugs acting against unstable detrusor contractions.

Posterior urethral valves: pre- and postnatal management

Posterior urethral valves are a common problem encountered by pediatric urologists. The diagnosis is most frequently suggested by antenatal screening ultrasound. A variety of pre- and postnatal parameters have been identified to aid in predicting ultimate renal outcome. These prognostic tools are invaluable to the clinician for counseling parents and for choosing appropriate management. Several approaches to the treatment of patients with posterior urethral valves exist, and the ideal strategy is debatable. As technology evolves, more options for early intervention become available. Whether early detection and antenatal intervention improve patient outcome remains to be proven.

Does neonatal pyeloureterostomy worsen bladder function in children with posterior urethral valves?

PURPOSE

We determine whether long-term bladder dysfunction is more frequent in children with posterior urethral valves who undergo early supravesical urinary diversion (pyeloureterostomy) than in those who undergo valve ablation.

MATERIALS AND METHODS

Urodynamic studies were performed in 59 boys with severe posterior urethral valves who were divided into 2 groups based on initial treatment of valve ablation (30) and bilateral pyeloureterostomy (29).

RESULTS

Of the 59 boys 25 (42%) had a normal bladder, including 11 with an over distended bladder and 34 (58%) had bladder dysfunction, including instability in 22, poor compliance in 9 and myogenic failure in 3. Of the 30 boys initially treated with valve ablation 14 (46.6%) had a normal bladder, including 7 with an over distended bladder and 16 (53.4%) had bladder dysfunction, including instability in 10, poor compliance in 4 and myogenic failure in 2. Of the 29 boys initially treated with temporary bilateral pyeloureterostomy 11 (38%) had normal bladders, 4 with an over distended bladder and 18 (62%) had bladder dysfunction, including instability in 12, poor compliance in 5 and myogenic failure in 1. There were no statistically significant differences in the number or type of bladder dysfunction between the diversion and valve ablation groups.

CONCLUSIONS

Therefore, temporary pyeloureterostomy did not affect bladder function adversely in the long term.

The changing urodynamic pattern from infancy to adolescence in boys with posterior urethral valves

OBJECTIVE

To determine whether bladder dysfunction in boys with posterior urethral valves (PUV) changes from a uniform pattern of hypercontractility during infancy to the hypocontractility found in adolescence, by reviewing serial urodynamic studies.

PATIENTS AND METHODS

Thirty boys with PUV and no voiding symptoms underwent a total of 86 urodynamic tests (mean 2.8 each). The first urodynamic study was undertaken at 1-4 years of age in 15 boys and at 5-13 years in 15. They were re-evaluated at least 3 years later; 15 patients underwent the first and last urodynamic study, respectively, at a mean age of 2.8 and 7.7 years (group A), 10 boys at 6.2 and 8. 8 years (group B) and five at 9.4 and 15.2 years (group C). In 10 boys aged > 5 years the first and last pressure-flow studies (PFS) were analysed using an advanced analysis (PFA) to better identify hypocontractility.

RESULTS

Bladder dysfunction was found in 21 of 30 (70%) boys at the first evaluation and in 18 (60%) at the last. In 25 boys the urodynamic pattern changed. Of the 15 boys in group A, 10 of 12 who had hypercontractility changed to normal (seven), low compliance (one) or hypocontractility (two), and two remained stable; two of the remaining three with normal urodynamic studies changed to hypocontractility, while one was unchanged. Among the 10 boys in group B, six with hypercontractility changed to normal (three) or hypocontractility (three); two with normal urodynamic findings and one with low compliance changed to hypocontractility. Of the five boys in group C who showed severe hypocontractility after puberty, three had a normal pattern, one low compliance and one hypercontractility before puberty. The PFA showed a 'weak' detrusor in four of the seven boys who were considered normal on standard PFS. At the urodynamic follow-up, the PFA pattern changed to a 'weak' detrusor in four boys who had a normal (two) or strong (two) detrusor at the first evaluation.

CONCLUSIONS

Bladder dysfunction in boys with PUV changes during childhood and through adolescence. The urodynamic pattern of hypercontractility generally found soon after valve ablation gradually changes to hypocontractility in many boys and this pattern seems to be the rule after puberty. The evidence from this series supports the hypothesis that long-term detrusor hyperactivity in boys with PUV leads to detrusor failure, but a longitudinal 15-year follow-up from birth to puberty is needed to validate this concept.