Long-term Status of Patients with Posterior Urethral Valves

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 valve: determining factors of long-term results]

Posterior urethral valves (PUV) is the most common congenital urine flow impairment in boys. Long-term prognosis involves: renal function impaired in 30 to 50% of PUV and leading to hyperdiuresis, low GFR and acidosis; bladder urodynamics impaired in 75% of PUV with abnormal urine storage, abnormal micturition and vesicoureteric reflux. Incontinence and recurrent urinary tract infections commonly reflect bladder and renal failures; abnormal bladder outlet leads to incontinence and abnormal ejaculation. The roles of antenatal treatments (vesico-amniotic shunts), neonatal treatments (resuscitation and endoscopic treatment of PUV) and long-term treatments (urinary diversions, bladder augmentation, alpha blockers, anticholinergic, dialysis and renal transplant) in the long-term outcomes of PUV are reviewed.

Detrusor hypocontractility in children with posterior urethral valves arises before puberty

OBJECTIVES

To assess prepubertal boys with posterior urethral valves (PUV) using an analysis of pressure-flow studies to evaluate the voiding phase and thus determine if myogenic failure (hypocontractility) arises before puberty and if it can be detected early.

PATIENTS AND METHODS

Eleven boys (8-13 years old) with PUV underwent urodynamics and the results were analysed using pressure-flow mathematical analysis (PFA) of the following variables of detrusor activity: contraction velocity (Vdet), detrusor contractile power expressed as power factor (WF) and Schafer's diagram, which differentiates a 'strong', 'normal' and 'weak' detrusor. Vdet and WF were compared with normal values previously determined in boys of similar age and considered 'low' if more than 2 SDs below the mean. The results of PFA were compared with standard pressure-flow studies and the three classical urodynamic patterns in boys with PUV, as determined by voiding symptoms. The subsequent PFA of seven of the 11 boys were also assessed as they had undergone previous urodynamics when < 8 years old.

RESULTS

As assessed by the three patterns of dysfunction, two boys had bladder instability, two had low compliance and three had hypocontractility, with four boys being normal. From the PFA, the Vdet and WF were lower than normal, respectively, in seven and nine of the 11 boys; Schafer's nomogram showed a 'weak' detrusor in seven boys. The PFA suggested a pathology in four of five boys with symptoms and in three of six with no symptoms (two of the six showing a 'low' WF). Moreover, in older (11-13 years) boys, all five had a 'weak' detrusor, a 'low' WF and four a 'low' Vdet. Of the seven patients who underwent repeat PFA, three had a stable WF 3 years later, one (normal) worsened slightly and two were clearly worse, while one, who underwent late (at 3 years old) valve ablation, had an increased WF.

CONCLUSIONS

The PFA showed hypocontractility in two-thirds of prepubertal boys with PUV, including asymptomatic patients. These findings confirm the hypothesis that bladder dysfunction in boys with PUV eventually causes detrusor myogenic failure and finally a postpubertal overdistended bladder.

Management of posterior urethral valves on the basis of urodynamic findings

PURPOSE

Abnormal urodynamic findings are common in boys with a history of posterior urethral valves. However, to our knowledge there are few reports on the results of treating these abnormal findings. We analyzed the treatment of abnormal urodynamic parameters and its outcome in 21 boys who underwent valve ablation.

MATERIALS AND METHODS

After valve ablation multichannel urodynamic studies were performed in 31 boys, including 21 in whom studies were done before and after therapy was started for abnormal parameters. Detrusor instability and impaired bladder compliance were treated with anticholinergics or augmentation cystoplasty, and impaired detrusor contractility was managed with clean intermittent catheterization.

RESULTS

Before therapy 17 of 21 boys had impaired compliance and detrusor instability, 2 had impaired compliance without instability and 2 had instability alone. After treatment 8 boys had impaired compliance and 4 had detrusor instability. After anticholinergics were initiated new onset myogenic failure in 2 boys necessitated clean intermittent catheterization. Of the 13 patients who presented with urinary incontinence 10 became dry and 3 had improvement with therapy. Vesicoureteral reflux in 10 boys at the time of the initial urodynamic study resolved in 7 with anticholinergic medication and in 1 after clean intermittent catheterization was begun for severely impaired compliance. All 21 boys were treated with anticholinergics and 2 were ultimately treated with augmentation cystoplasty. Clean intermittent catheterization was also instituted in 5 patients, including the 2 who required clean intermittent catheterization after myogenic failure developed. Five boys with high voiding pressures were found to have outlet obstruction due to residual valve tissue in 2, bladder neck obstruction in 2 and urethral stricture in 1 despite normal flow rates in 2.

CONCLUSIONS

Urodynamic studies are helpful in guiding therapy in boys after valve ablation. Anticholinergic therapy can improve compliance, decrease detrusor instability, improve continence and eliminate vesicoureteral reflux in the majority of boys, although there is an associated risk of myogenic failure. Flow rates and fluoroscopic voiding studies are often unable to detect outlet obstruction and must be obtained in conjunction with voiding pressure measurements to make this diagnosis.

Long-term renal function in the posterior urethral valves, unilateral reflux and renal dysplasia syndrome

PURPOSE

The syndrome of posterior urethral valves, persistent unilateral reflux and renal dysplasia (VURD) is said to be protective of the contralateral nonrefluxing kidney and the outcome for renal function is reported to be excellent. We tested this hypothesis in our patients by replicating previous studies but with longer followup and glomerular filtration rate data.

MATERIALS AND METHODS

We retrospectively reviewed the records of 183 boys presenting with posterior urethral valves between 1980 and 1989, including 12 who underwent nephrectomy for ipsilateral nonfunction and fulfilled all criteria for the VURD syndrome. Mean age at the most recent followup was 8.5 years. Serial serum creatinine levels and glomerular filtration rates were analyzed and compared to age matched normal values.

RESULTS

Histological evaluation revealed dysplasia in all kidneys, confirming the VURD syndrome. Followup plasma creatinine was normal 67% of the patients during year 2 of life, 50% between ages 4 and 5 years, and only 30% between ages 8 and 10 years. Glomerular filtration rate was within the normal range in 25% of boys tested in year 2 of life, and between ages 5 and 8 years.

CONCLUSIONS

Our data do not support the protective effect of the VURD syndrome on long-term renal function. All patients with posterior urethral valves require diligent long-term followup.

Comparative urodynamic findings after primary valve ablation, vesicostomy or proximal diversion

PURPOSE

There is little known about the effect of urinary diversion on the bladder of children with posterior urethral valves. There is a fear that diversion may result in contracted noncompliant bladders. We wished to compare urodynamic parameters in patients who underwent primary ablation of posterior urethral valves and in those who underwent diversion in the form of vesicostomy or pyelostomy.

MATERIALS AND METHODS

Urodynamics were done in 32 boys with a history of posterior urethral valves divided into 3 groups based on initial treatment: 1) transurethral valve ablation; 2) cutaneous vesicostomy, subsequent closure and valve ablation, and 3) proximal cutaneous pyelostomy, subsequent reconstitution and valve ablation.

RESULTS

Patients who underwent initial diversion with vesicostomy or pyelostomy had bladders with larger functional capacity, better compliance and less instability. Chronic renal failure developed in 25% of the patients who underwent primary valve ablation and 33% of those who underwent diversion. Average period of diversion in vesicostomy and pyelostomy patients was 25 months.

CONCLUSIONS

Based on our findings temporary diversion does not seem to damage bladders. On the contrary, placing a damaged bladder at rest may help to improve bladder function. Bladder function following reconstitution correlated poorly with ultimate outcome and progression to renal failure. While we do not recommend temporary diversion as the treatment of choice for patients with posterior urethral valves, we believe that when chosen as treatment, it can be safely performed with little risk of further damage to the bladder.

The changing urodynamic pattern in valve bladders during infancy

Bladder dysfunction in boys with posterior urethral valves is well documented in studies of long-term followup. These reports suggest that dysfunctional bladders can be divided into 3 main types, including unstable, low compliant and over distended. To our knowledge urodynamic findings at presentation during infancy have not been described previously. We report on 16 male patients born between 1989 and 1993 who presented with symptoms of posterior urethral valves between birth and age 5 months, and who were followed with repeated urodynamic evaluations for a mean of 19 months. At presentation the bladder was hypercontractile with low capacity. During the first 3 years of life, the urodynamic pattern changed with vanishing hypercontractility and increasing bladder capacity, although instability remained unchanged with emptying difficulties. Thus, the 3 patterns of bladder dysfunction reported in older boys after resection of posterior urethral valves could not be found in infants and small children.

Persistent polyuria after posterior urethral valves

OBJECTIVE

To assess urinary concentrating ability, urine production and glomerular filtration rates in a cohort of boys with previously treated posterior urethral valves.

PATIENTS AND METHODS

Urinary concentrating capacity was assessed in 51 boys aged 5.4-9.9 years with previously treated posterior urethral valves. They all completed urinary frequency/volume charts, permitting calculation of 24 h urine volumes. The osmolality of an overnight urine collection was measured and, if < 800 mOsm/kg (n = 40), an intramuscular injection of desamino-cys-1-8-D-arginine vasopressin was given to determine the maximum concentrating ability. The glomerular filtration rate (GFR) was estimated from the plasma clearance of 51Cr-ethylenediamine tetra-acetic acid following a single intravenous injection.

RESULTS

The mean 24 h urine volume was 1025 +/- 448 (SD) mL. The mean overnight urine flow rate was 28.4 +/- 17.9 mL/h. Urinary concentrating capacity was impaired (< 800 mOsm/kg) in 30 (59%) of the boys and < 300 mOsm/kg in eight (16%). The mean GFR was 81 +/- 38 mL/min/1.73 m2SA. Significant correlations were noted between the GFR, the maximum urine concentration and the 24 h urine volume.

CONCLUSION

Persistent polyuria after valve ablation occurs in boys with posterior urethral valves. This has implications both in terms of urinary continence and on-going renal impairment.

The sexual and reproductive consequences of congenital genitourinary anomalies

The major congenital anomalies of the genitourinary tract may result in disturbances of sexual and reproductive function. In general the children grow up with the same aspirations as their more normal peers, which are to marry, have intercourse and produce children. Some achieve this despite the deformities and in others specific reconstructive surgery may be needed. In exstrophy the vagina lies parallel to the floor when the girl is standing and the introitus is seen on the lower abdominal wall rather than in the perineum. Episiotomy is required in 34% and formal vaginoplasty in 23% of the cases. The exstrophy penis has a tight dorsal chordee that must be corrected to allow intercourse. The neurological and social consequences of myelomeningocele do not prevent patients from having an interest in sex. Those who are able to walk are likely to have normal sexual function compared to about 50% of those who are wheelchair bound. The recurrence risk for neural tube defects in their offspring is 1:50 for sons and 1:13 for daughters regardless of the sex of the affected parent. The physiological consequences of posterior urethral valves result in weak ejaculation in 50% and highly viscous and alkaline semen in 50% of the cases. Of male patients with ambiguous genitalia or micropenis 75% have normal intercourse.

A fetal lamb model of partial urethral obstruction: experimental protocol and results

The functional effects of bladder outlet obstruction in the developing urinary tract are well recognized in patients born with posterior urethral valves, in whom a spectrum of bladder dysfunction has been described. To better understand the changes occurring in the partially obstructed developing lower urinary tract, a fetal lamb model of partial urethral obstruction was developed. Fetal lambs at 90 days' gestation underwent surgical placement of a silver ring (ex utero) at the level of the proximal bladder neck, with concomitant ligation of the urachus. Control animals underwent urethral ligation only. The lambs were then allowed to go through normal gestation, and ewes were delivered spontaneously. The animals were studied between 2 and 7 days after birth. The postmortem examination showed that the ring was just distal to the bladder neck, around the proximal urethra. This resulted in gradual, partial occlusion of the urethra. Bladder weights, bladder wall thickness, and bladder capacity were significantly increased in the partially obstructed animals as compared with the controls. There was little or no upper tract dilatation in the obstructed group. This animal model, the first to produce gradual outflow obstruction in the fetus, provides a reproducible model of partial urethral obstruction. The model can be used to assay the biochemical and physiological changes found in the developing urinary tract of fetal lambs submitted to intravesical obstruction.

Developmental alterations in the fetal lamb bladder subjected to partial urethral obstruction in utero

To identify the structural changes seen in the developing bladder subjected to outflow obstruction, a fetal lamb model was developed. With this model, which attempts to reproduce conditions such as those found in posterior urethral valves, quantitative biochemical parameters were used to evaluate the effects of partial outflow obstruction on detrusor cellularity and innervation in the developing bladder. Partial urethral obstruction was created in 9 fetal sheep (90 to 100 days gestation), 6 sham operated animals serving as controls. Fetuses were delivered at term and sacrificed. Bladders were removed and weighed. Mucosa free detrusor was assayed for DNA and choline acetyltransferase (ChAT) activity, indices of cell number and cholinergic innervation, respectively. In similar specimens of detrusor, cell ploidy and nuclear size were determined by flow cytometry and nuclear morphometry, respectively. The results showed that partial urethral obstruction in utero resulted in a significant increase in bladder weight (p < 0.05) and total detrusor DNA content (p < 0.01). With the increase in detrusor DNA content, there was a parallel increase in total detrusor ChAT activity. These results suggest that early development of the bladder is altered both on a cellular level (increase in cellularity) and a neural level (increase in cholinergic nerve density) under conditions of mechanical distension.

Renal transplantation in young boys with posterior urethral valves: preliminary report

Seven boys (mean age 38 months) with posterior urethral valves underwent renal transplantation between June 1988 and August 1991. Urodynamic studies were performed before transplantation in 6/7 patients. In 4 the investigation indicated bladders of capacity and compliance which were deemed suitable for transplantation. Two patients had poorly compliant bladders; one of these underwent bladder augmentation before engraftment and the other proceeded to transplantation without bladder surgery. Six patients have functioning renal allografts with a mean follow-up of 1.3 years and a mean plasma creatinine of 51.6 mumol/l. Mean glomerular filtration rate (ml/min/1.73 m2 SA) 6 months after transplantation was 76.8 and at 1 year it was 84.5. In one patient early rejection was followed by transplant nephrectomy. Careful pre-operative evaluation is mandatory for a successful outcome of renal transplantation in young boys with posterior urethral valves.

Radiographic and serologic correlates of azotemia in patients with posterior urethral valves

A retrospective statistical analysis with a minimum followup of 10 years was done on 102 patients who presented in early childhood with posterior urethral valves. All patients were treated with initial bladder drainage. Factors correlating with the development of renal failure were evaluated. No patient with a normal kidney on 1 side had renal failure. Calculated glomerular filtration rate was significantly higher in patients who retained adequate renal function (80.7 +/- 17.8 ml. per minute per 1.73 m.2), as compared with those who had renal failure (18.6 +/- 9.6 ml. per minute per 1.73 m.2). Patients with renal failure also had a significantly higher serum creatinine level at stabilization (2.0 +/- 0.8 mg./dl.) than those who had adequate renal function (0.5 +/- 0.2 mg./dl.). The presence of bilateral high grade vesicoureteral reflux, hydronephrosis and nonfunction was significantly higher in patients with renal failure. Patient age at presentation was not a significant factor. These data represent a guideline for the prognosis and management protocols of infants with dilated upper urinary tracts and posterior urethral valves.