HIGH INCIDENCE OF A GENERALLY SMALL KIDNEY AND PRIMARY VESICOURETERAL REFLUX

Abstract

We distinguished the scintigraphy pattern of congenital reflux nephropathy from that of acquired scarring in children with primary vesicoureteral reflux. We retrospectively evaluated the frequency and pattern of renal scintigraphy abnormalities in 41 patients with prenatally detected primary vesicoureteral reflux and in 322 with a mean age plus or minus standard deviation of 3.6 + or - 1 years in whom primary reflux was detected after urinary tract infection. Dimercapto-succinic acid scintigraphy was performed 4 to 6 and 1 to 4 months after reflux was diagnosed and/or the infection was cured in patients with urinary tract infection and prenatal detection, respectively. We identified 3 patterns of renal damage, including overall decreased uptake of renal radionuclide that was 20% to 40% of relative uptake, focal defects in uptake and shrunken kidney with relative uptake less than 20%. Scintigraphy revealed renal damage in 12 prenatally detected cases of vesicoureteral reflux, including overall decreased uptake in 58% and shrunken kidney in 42%, and in 111 cases of reflux detected at urinary tract infection, including overall decreased uptake in 50%, uptake focal defects in 37% and shrunken kidney in 13%. In the urinary tract infection group overall decreased uptake was present in 25 of 90 boys and in 40 of 232 girls (p = 0.05). Of these children 15% of the girls had uptake focal defects and 17% had overall decreased uptake. Overall decreased uptake and uptake focal defects were significantly more common in kidney-ureter units with reflux grade 4 or greater than in those with grade 3 or less (p = 0. 00001 and 0.027, respectively). When assuming that overall decreased radionuclide uptake indicates congenital reflux nephropathy and uptake focal defects indicate postnatal acquired scarring, congenital reflux nephropathy appears to be an important cause of renal damage in children with primary vesicoureteral reflux even beyond the neonatal age and even in girls. This finding is of interest because postnatally acquired scarring may but congenital reflux nephropathy may not be prevented.