High incidence of a generally small kidney and primary vesicoureteral reflux

Purpose: We distinguished the scintigraphy pattern of congenital reflux nep hropathy from that of acquired scarring in children with primary vesicouret eral reflux. Materials and Methods: We retrospectively evaluated the frequency and patte rn of renal scintigraphy abnormalities in 41 patients with prenatally detec ted primary vesicoureteral reflux and in 322 with a mean age plus or minus standard deviation of 3.6 +/- 1 years in whom primary reflux was detected a fter urinary tract infection. Dimercapto-succinic acid scintigraphy was per formed 4 to 6 and 1 to 4 months after reflux was diagnosed and/or the infec tion was cured in patients with urinary tract infection and prenatal detect ion, respectively. Results: We identified 3 patterns of renal damage, including overall decrea sed uptake of renal radionuclide that was 20% to 40% of relative uptake, fo cal defects in uptake and shrunken kidney with relative uptake less than 20 %. Scintigraphy revealed renal damage in 12 prenatally detected cases of ve sicoureteral reflux, including overall decreased uptake in 58% and shrunken kidney in 42%, and in 111 cases of reflux detected at urinary tract infect ion, including overall decreased uptake in 50%, uptake focal defects in 37% and shrunken kidney in 13%. In the urinary tract infection group overall d ecreased 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% ha d overall decreased uptake. Overall decreased uptake and uptake focal defec ts 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, res pectively). Conclusions: When assuming that overall decreased radionuclide uptake indic ates congenital reflux nephropathy and uptake focal defects indicate postna tal acquired scarring, congenital reflux nephropathy appears to be an impor tant cause of renal damage in children with primary vesicoureteral reflux e ven 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.