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

Posterior urethral valve

BACKGROUND

Posterior urethral valve (PUV) is a significant cause of morbidity, mortality and ongoing renal damage in children. It accounts for end-stage renal disease in a proportion of children. This article aims at highlighting the current trend in the management of boys with posterior urethral valve.

DATA SOURCES

PubMed/Medline and bibliographic search for posterior urethral valve was done. Relevant literatures on presentation, pathology, evaluation, management and outcomes of PUV were reviewed.

RESULTS

PUV which is increasingly diagnosed prenatally presents a spectrum of severity. The varied severity and degree of obstruction caused by this abnormality depend on the configuration of the obstructive membrane within the urethra. The decision to intervene prenatally is dependent on gestational age, amniotic volume, and renal function of fetal urine aspiration. Identification of the patients who may benefit from early intervention remains inconclusive. Endoscopic ablation of the valve is the gold standard of treatment but use of Mohan's valvotome and other modalities are invaluable in developing countries where endoscopic facilities are limited. Proximal urinary diversion may result in poor bladder compliance and should be reserved for patients with persisting or increasing upper urinary tract dilatation, increasing serum creatinine or inappropriate instruments. The behavior of the bladder and its subsequent management after valve ablation may influence the long-term renal outcome in PUV patients.

CONCLUSIONS

The care of children with PUV continues to improve as a result of earlier diagnosis by ultrasound, developments in surgical technique and meticulous attention to neonatal care. The ultimate goal of management should be to maximize renal function, maintain normal bladder function, minimize morbidity and prevent iatrogenic problems.

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.

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.