Posterior Urethral Valves (PUV): Prenatal Ultrasound Findings and their Correlation with Glomerular Filtration Rate (GFR) at I Year of Age

Abstract

PURPOSE The prognostic value of prenatal ultrasound in boys with PUV is controversial, especially in those with normal amniotic fluid (AF) volumes. This study correlates the prenatal status with the outcome of renal function at age 1-year. MATERIAL AND METHODS 50 unselected boys with PUV presenting to our unit, 30 with a prenatal history at one of two referring fetal medicine units are included in the analysis. GFR (Cr51 EDTA C-slope clearance ml/min/1.73 m 2) at 1-year of age was correlated with amniotic fluid volume (AF; n=25) and with the status of pre-natal renal cortical echogenecity (n=18). GFR results were classified into 3 groups; Normal (>80mls/min/1. 73m 2), Impaired (30 – 80 ml/min/1.73 m 2) and End Stage Renal Disease (ESRD) (<30ml/min/1.73 m 2). ANOVA single factor statistical analysis was used. RESULTS Prenatal detection did not affect the outcome of GFR compared with post-natal presentation only (means 71.73 v 71.5 respectively). Normal AF was associated with a better GFR compared with reduced AF (86 v 30; P < 0.001), all those with reduced AF had a low GFR. Normal AF did not always correlate with a normal GFR; 8/19 had impaired renal function. Prenatal bilateral echogenic kidneys were associated with a poor GFR outcome compared to normal and unilateral echogenic kidneys (P=0.005). CONCLUSIONS “Normal” AF with PUV obstruction does not predict a normal GFR at 1-year of age. Pre-natal bilateral echogenic kidneys and reduced AF are associated with a poor renal outcome at age 1-year. A “Normal” ultrasound at 20 weeks gestation does not exclude PUV obstruction.