A clinical predictive model of chronic kidney disease in children with posterior urethral valves.

BACKGROUND: Posterior urethral valves (PUVs) are associated with severe consequences to the urinary tract and are a common cause of chronic kidney disease (CKD). The aim of this study was to develop clinical predictive model of CKD in a cohort of patients with PUVs. METHODS: In this retrospective cohort study, 173 patients with PUVs were systematically followed up at a single tertiary unit. The primary endpoint was CKD ≥ stage 3. Survival analyses were performed by Cox regression proportional hazard models with time-fixed and time-dependent covariables. RESULTS: Mean follow-up time was 83 months (SD, 70 months). Sixty-five children (37.6%) developed CKD stage ≥ 3. After adjustment by the time-dependent Cox model, baseline creatinine, nadir creatinine, hypertension, and proteinuria remained as predictors of the endpoint. After adjustment by time-fixed model, three variables were predictors of CKD ≥ stage 3: baseline creatinine, nadir creatinine, and proteinuria. The prognostic risk score was divided into three categories: low-risk (69 children, 39.9%), medium-risk (45, 26%), and high-risk (59, 34.1%). The probability of CKD ≥ stage 3 at 10 years age was estimated as 6%, 40%, and 70% for patients assigned to the low-risk, medium-risk, and high-risk groups, respectively (P < 0.001). The main limitation was the preclusion of some relevant variables, especially bladder dysfunction, that might contribute to a more accurate prediction of renal outcome. CONCLUSION: The model accurately predicts the risk of CKD in PUVs patients. This model could be clinically useful in applying timely intervention and in preventing the impairment of renal function.

Posterior urethral valves: comparison of clinical outcomes between postnatal and antenatal cohorts.

BACKGROUND: Posterior urethral valves (PUVs) constitute the most common infravesical urinary obstruction in boys and are often accompanied by severe consequences to the lower and upper urinary tract. Currently, about two-thirds of diagnosis of PUVs has been suspected by prenatal ultrasonography findings. The aim of this study was to compare long-term clinical outcomes in two groups of patients with PUVs, with antenatal vs. postnatal diagnosis. STUDY DESIGN: This was a retrospective cohort study of 173 patients with PUVs systematically followed up in a tertiary center. Median follow-up time was 66.5 months (interquartile range [IQ], 11.4-147.9 months) for those patients who survived neonatal period. Seventy-nine (45.6%) patients were followed up for more than 5 years and 55 (32%) for more than 10 years. For analysis, the cohort was stratified into two groups according to the clinical presentation (prenatal vs. postnatal). The events of interest were urinary tract infection (UTI), surgical interventions, proteinuria, hypertension, chronic kidney disease (CKD), and death. Survival analyses were performed to evaluate time until occurrence of the events. RESULTS: Sixty-two patients (35.8%) were diagnosed by fetal sonography. Patients of postnatal group presented a higher incidence rate of UTI episodes (6.5, 95% confidence interval [CI], 4.9-8.3) than antenatal group (1.2, 95% CI, 0.4-2.7) (P < 0.001). Thirty-six patients (21%) presented hypertension, and 77 (44.5%) had persistent mild proteinuria. There was no significant difference in the estimated incidence of hypertension (P = 0.28) and proteinuria (P = 0.78) between antenatal and postnatal groups. The cumulative incidence of CKD stage ≥3 was estimated to be about 37% at 10 years of age, and 56% at 18 years of age. By survival analysis, there was no significant difference in the estimated incidence of CKD stage ≥3 (log-rank = 0.32, P = 0.57) and CKD stage 5 (log-rank = 1.08, P = 0.28, Figure) between antenatal and postnatal groups. Of 173 patients included in the analysis, 13 (7.5%) died during follow-up with a median age of 2.6 months (IQ, 15 days-62 months). Survival analyses have not shown any significant difference in the estimated incidence of death between antenatal and postnatal groups (log-rank = 1.38, P = 0.24). CONCLUSION: The study findings did not corroborate the initial hypothesis that the rates of renal function declining in patients with PUVs would be attenuated by an early diagnosis and intervention after antenatal diagnosis.

Cystoscopic placement of transurethral stent in a fetus with urethral stenosis.

We report the case of a fetus with severe megabladder, displaying the 'keyhole' sign on ultrasound imaging, that underwent cystoscopy at 22 weeks' gestation. There was a familial history of mild urethral atresia. Fetal cystoscopy revealed congenital urethral atresia. A guide wire was advanced through the fetal urethra and a transurethral vesicoamniotic stent was placed successfully. The fetus was delivered at 36 weeks' gestation and postnatal cystoscopy confirmed the absence of posterior urethral valves or urethral atresia. The infant was 5 years old with normal renal function at the time of writing. We conclude that fetal cystoscopic placement of a transurethral stent for congenital urethral stenosis is feasible.

Válvulas de uretra posterior y ausencia de reflujo vesicoureteral bilateral: Seguimiento de la función renal / Posterior urethral valves and lack of bilateral vesicoureteral reflux: Renal function follow-up background

Introducción. Las válvulas de uretra posterior congénitas son repliegues de mucosa que se originan únicamente en varones. Constituyen la causa más común de obstrucción de la vía urinaria en el período neonatal. Debido a la alta presión que se genera en la vejiga urinaria, con frecuencia se acompañan de reflujo vesicoureteral (RVU) bilateral. En ocasiones, el reflujo es unilateral, asociado a displasia renal homolateral (síndrome VURD). Se ha comunicado que en estos casos el pronóstico a largo plazo es mejor, no obstante, existe muy poca experiencia sobre éste en el subtipo constituido por los niños en los que no existe reflujo. Métodos. Se estudiaron a 4 pacientes con válvulas de uretra posterior y ausencia de RVU, en seguimiento por un tiempo comprendido entre 3 y 6 años. Se describe su evolución desde el diagnóstico, la cirugía realizada, los marcadores de función renal, estudios de imagen y evolución. Así como los valores de los cocientes calculados entre las concentraciones urinarias de N-acetil-glucosaminidasa (NAG) y de microalbúmina con respecto a la creatinina urinaria. Resultados. La función glomerular renal fue normal en los 4 casos. Únicamente un paciente tenía un discreto defecto de la capacidad de concentración y un ligero incremento en la eliminación urinaria de NAG. Conclusiones. El manejo médico y quirúrgico de las válvulas de uretra posterior ha mejorado la supervivencia de los niños con este diagnóstico. La ausencia de RVU, la presencia de ascitis urinaria o urinoma en el período neonatal y la asociación con un gran divertículo vesical proveen un mecanismo de "escape", lo que resulta en una preservación de la función renal.

Introduction. The posterior urethral congenital valves are mucosal folds in the posterior urethra that occur only in male patients. They are the most common cause of urinary tract obstruction in the neonatal period. Due to hyper pressure that begins in the urinary bladder, it is highly frequent for these to come together with bilateral vesico-ureteral reflux. In some cases, this reflux is unilateral and is associated with posterior urethral valve and renal dysplasia (VURD syndrome). A better long-term renal outcome in these cases has been reported. Nevertheless, there is very little experience regarding prognosis of the remaining group of children without reflux. Methods. We studied 4 children with posterior urethral valves and lack of vesico-ureteral reflux with controlled follow-up during 3 and 6 years. We described disease presentation and clinical course from diagnosis, surgical intervention, renal function, radiologic features, N-acetylglucosaminidase (NAG), and microalbuminuria during follow-up. Results. Renal glomerular function is normal in all 4 cases. Only one patient had a mild default in urinary concentration capacity and a slight increase in urinary elimination of N-acetylglucosaminidase. Conclusion. Medical and surgical management of the posterior urethral valves has improved long-term renal outcome in the sepatients. Lack of vesico-ureteral reflux, urinary ascites, urinary extravasation, and large congenital bladder diverticula can serve as a pop-off mechanism to buffer hyperpressure in the urinary tract, leading to the preservation of improved renal function in boys with posterior urethral valves.