The Use of Renal Parenchymal Area in Children With High Grade Vesicoureteral Reflux

Abstract

Purpose We sought to apply 2-dimensional sonographic measurements of renal parenchymal area in children with high grade vesicoureteral reflux to assess reliability and accuracy in estimating differential renal function, and in predicting clinical outcome compared to traditional 1-dimensional sonographic measurements. Materials and Methods We retrospectively evaluated 121 sonograms from 30 patients with a grade 4 or 5 primary vesicoureteral reflux, including 14 who underwent ureteral reimplantation during followup and 16 who were followed on prophylactic antibiotic therapy. One-dimensional sonographic measurements of longitudinal length and bipolar thickness were determined in refluxing and contralateral kidneys, as were 2-dimensional measurements of longitudinal parenchymal area using computer planimetry. Renal length, bipolar thickness and parenchymal area were compared to renal function data determined by nuclear renography. Renal length and area was also represented as a percent of age adjusted normal values using previously published nomograms. Results Differential renal function correlated well with differential parenchymal area for all patients (r = 0.924). This correlation persisted in patients with (r = 0.917) and without scarring (r = 0.890), as determined by dimercapto-succinic acid scan. Differential length did not correlate as well (r = 0.661) and bipolar parenchymal thickness did not correlate at all (r = 0.021). Sonographic age adjusted area of the refluxing kidneys was approximately two-third normal. No statistically significant difference was observed among age adjusted renal area of the observation, preoperative and postoperative groups. Contralateral kidney area was not significantly different than normal. Conclusions Our data indicate that serial sonographic measurements of longitudinal renal parenchymal area provide a simple and accurate method of monitoring renal growth and function in patients with high grade vesicoureteral reflux. In contrast to 1-dimensional measurements of renal length and bipolar parenchymal thickness, renal parenchymal area correlates well with renal function. Area also appears to be a more sensitive method of monitoring renal growth in children with vesicoureteral reflux.