Posterior Urethral Valves with Lower Urinary Tract Symptoms: Perspective on Urodynamics

Mid-short-term risk factors for chronic renal failure in children with posterior urethral valve

OBJECTIVES

To analyze the mid-short-term risk factors for chronic renal failure (CRF) in children with posterior urethral valve (PUV) after valve ablation.

MATERIALS AND METHODS

A retrospective study of 143 patients with PUV who underwent operation was performed. Patients were divided into CRF group (n = 39) and non-CRF group (n = 104). Clinical data of both groups such as the first resection age, last resection age, number of operations, the maximal detrusor pressure (Pdet_max), and vesicoureteral reflux (VUR) were collected and analyzed.

RESULTS

The first resection age, last resection age, and the Pdet_max of patients in the CRF group were higher than those of patients in the non-CRF group (P < 0.05). Multiple regression analysis showed that the indicators related to chronic renal failure were last resection age (β = 1.034, P < 0.05) and Pdet_max (β = 1.068, P < 0.05). The cut-off value of last resection age was 35.5 months, Pdet_max was 41.65 cmH₂O. There was positive correlation of final blood creatinine with last resection age and Pdet_max.

CONCLUSION

The last resection age and Pdet_max are the risk factors of chronic renal failure in children with PUV. A Pdet_max of lower than 41.65 cmH₂O indicates a good prognosis of renal function in patients with PUV.

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.

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.