Vesicoureteral Reflux in Patients With Posterior Urethral Valves

Posterior urethral valves, pressure pop-offs, and kidney function: systematic review and meta-analysis

PURPOSE

To determine the role of pressure pop-off mechanisms, including vesicoureteral reflux and renal dysplasia (VURD) syndrome, in determining long-term kidney outcomes in boys with posterior urethral valves (PUV).

METHODS

A systematic search was performed in December 2022. Descriptive and comparative studies with a defined pressure pop-off group were included. Assessed outcomes included end-stage renal disease (ESRD), kidney insufficiency (defined as chronic kidney disease [CKD] stage 3 + or SCr > 1.5 mg/dL), and kidney function. Pooled proportions and relative risks (RR) with 95% confidence intervals (CI) were extrapolated from available data for quantitative synthesis. Random-effects meta-analyses were performed according to the study design and techniques. The risk of bias was assessed with the QUIPS tool and GRADE quality of evidence. The systematic review was prospectively registered on PROSPERO (CRD42022372352).

RESULTS

A total of 15 studies describing 185 patients with a median follow-up of 6.8 years were included. By the last follow-up, overall effect estimates demonstrate the prevalence of CKD and ESRD to be 15.2% and 4.1%, respectively. There was no significant difference in the risk of ESRD in patients with pop-off compared to no pop-off patients [RR 0.34, 95%CI 0.12, 1.10; p = 0.07]. There was a significantly reduced risk for kidney insufficiency in boys with pop-off [RR 0.57, 95%CI 0.34, 0.97; p = 0.04], but this protective effect was not re-demonstrated after excluding studies with inadequate reporting of CKD outcomes [RR 0.63, 95%CI 0.36, 1.10; p = 0.10]. Included study quality was low, with 6 studies having moderate risk and 9 having a high risk of bias.

CONCLUSIONS

Pop-off mechanisms may be associated with reducing the risk of kidney insufficiency, but current certainty in the evidence is low. Further research is warranted to investigate sources of heterogeneity and long-term sequelae in pressure pop-offs.

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.

Developmental pathology of congenital kidney and urinary tract anomalies

Congenital anomalies of the kidneys or lower urinary tract (CAKUT) are the most common causes of renal failure in children and account for 25% of end-stage renal disease in adults. The spectrum of anomalies includes renal agenesis; hypoplasia; dysplasia; supernumerary, ectopic or fused kidneys; duplication; ureteropelvic junction obstruction; primary megaureter or ureterovesical junction obstruction; vesicoureteral reflux; ureterocele; and posterior urethral valves. CAKUT originates from developmental defects and can occur in isolation or as part of other syndromes. In recent decades, along with better understanding of the pathological features of the human congenital urinary tract defects, researchers using animal models have provided valuable insights into the pathogenesis of these diseases. However, the genetic causes and etiology of many CAKUT cases remain unknown, presenting challenges in finding effective treatment. Here we provide an overview of the critical steps of normal development of the urinary system, followed by a description of the pathological features of major types of CAKUT with respect to developmental mechanisms of their etiology.

All grown up: A transitional care perspective on the patient with posterior urethral valves

N/A

Risk factors for progression to end-stage renal disease in children with posterior urethral valves

OBJECTIVE

To identify the variables which affect long-term renal outcome in children with posterior urethral valves (PUV).

MATERIALS AND METHODS

Retrospective analysis of 260 children with PUV who underwent ablation of valves in 1992-2008 at our tertiary care center. The following risk factors for progression to end-stage renal disease (ESRD) were analyzed: nadir serum creatinine greater than 1.0mg/dl, bilateral grade 3 or higher VUR at diagnosis, recurrent febrile UTIs, and severe bladder dysfunction. Patients were divided into two groups: those who developed ESRD (group 1) and those who did not (group 2).

RESULTS

Forty (17.62%) patients had nadir serum creatinine >1mg/dl. At time of initial presentation, high-grade VUR was seen in 63.1% and 33.5% of groups 1 and 2, respectively (P=0.002). Overall, 77 (34%) of the boys developed breakthrough urinary tract infections: 37.03% and 33.5% in groups 1 and 2, respectively (P=1). Fifty-nine (26%) patients were found to have severe bladder dysfunction: 77.8% and 19% in groups 1 and 2, respectively (P<0.0001). Twenty-seven (11.89%) patients progressed to ESRD, at mean age of 11.21 years (5-16). On univariate analysis, the risk-predicting variables were: nadir serum creatinine value greater than 1mg/dl (P<0.0001), bilateral high-grade VUR (P=0.002) and severe bladder dysfunction (P<0.0001). On multivariate logistic regression analysis, nadir serum creatinine greater than 1mg/dl (OR 23.79; CI 8.20-69.05) and severe bladder dysfunction (OR 5.67; CI 1.90-16.93) were found to be independent risk factors predictive of ultimate progression to ESRD.

CONCLUSIONS

Nadir serum creatinine and bladder dysfunction are the main factors affecting long-term renal outcome in cases of PUV. Early identification and treatment of bladder dysfunction may thus be beneficial.

[Posterior urethral valves: prenatal diagnosis, neonatal data and outcome]

AIM OF THE STUDY

To evaluate the impact of prenatal diagnosis on the epidemiology and outcome of children with posterior urethral valves (PUV), considering that today termination of pregnancy may be proposed in the most severe cases.

PATIENTS AND METHODS

Forty-three cases of patients with PUV were diagnosed between 1998 and 2007 in the Languedoc-Roussillon region. In this study, we detailed the prenatal data and postnatal outcome of those patients with a mean follow-up period of 7.6 years.

RESULTS

Medical interruption of pregnancy was performed in 15 severe cases. One death in utero was also observed. Twenty-seven patients were managed postnatally and one child died during the neonatal period because of lung hypoplasia. For the 26 remaining patients at the end of the follow-up period, 5 had mild renal insufficiency with a creatinine clearance calculated with the Schwartz formula of less than 80 ml/min/1.73 m2. One reached end-stage renal failure at the age of 7 years. Proteinuria and hypertension were rare.

DISCUSSION AND CONCLUSION

Today, because of the increase in medical termination of pregnancy in the most severe cases, most of the children born alive with PUV experienced a better renal prognosis when compared with previous data. Prenatal diagnosis and therapeutic progress significantly modified the epidemiology and outcome of this disease. Nevertheless, the best predictor of renal outcome remains renal function at 1 year of age.

Vesicoureteral reflux

Vesicoureteral reflux (VUR), the retrograde flow of urine from the bladder toward the kidney, is common in young children. About 30% of children with urinary tract infections will be diagnosed with VUR after a voiding cystourethrogram. For most, VUR will resolve spontaneously; 20% to 30% will have further infections, but few will experience long-term renal sequelae. Developmentally, VUR arises from disruption of complex signaling pathways and cellular differentiation. These mechanisms are probably genetically programmed but may be influenced by environmental exposures. Phenotypic expression of VUR is variable, ranging from asymptomatic forms to severe renal parenchymal disease and end-stage disease. VUR is often familial but is genetically heterogeneous with variability in mode of inheritance and in which gene, or the number of genes, that are involved. Numerous genetic studies that explore associations with VUR are available. The relative utility of these for understanding the genetics of VUR is often limited because of small sample size, poor methodology, and a diverse spectrum of patients. Much, if not all, of the renal parenchymal damage associated with end-stage disease is likely to be congenital, which limits the opportunity for intervention to familial cases where risk prediction may be available. Management of children with VUR remains controversial because there is no strong supportive evidence that prophylactic antibiotics or surgical intervention improve outcomes. Furthermore, well-designed genetic epidemiological studies focusing on the severe end of the VUR phenotype may help define the causal pathway and identify modifiable or disease predictive factors.

Obstructive uropathy

Routine second trimester ultrasound screening has resulted in more infants diagnosed with antenatal hydronephrosis. Current recommendations suggest postnatal evaluation of all infants with a renal pelvic diameter >5 mm with ultrasound and voiding cystourethrogram (VCUG.) There are many etiologies of obstructive uropathy including ureteropelvic junction (UPJ) obstruction, ureterovesical junction (UVJ) obstruction, posterior urethral valves (PUV), prune belly syndrome, and vesicoureteral reflux (VUR). Obstructive uropathy can result in tubular damage and decreased nephron number. Tubular damage can result in sodium wasting, hyperkalemic acidosis, and nephrogenic diabetes insipidus. Most patients do not require renal replacement therapy in the neonatal period; however, chronic renal insufficiency can occur if the neonate has a significant reduction in nephron number or progressive renal damage from obstruction or infection.