Comparative study between intravenous urography and renal scintigraphy with DMSA for the diagnosis of renal scars in children with vesicoureteral reflux

RESUMO

PURPOSE: To assess the value of intravenous urography (IVU) in detecting and grading the renal scar, comparing its results with those of scintigraphy with dimercaptosuccinic acid (DMSA). MATERIALS AND METHODS: The study included 43 children investigated by DMSA and IVU, who had vesicoureteral reflux diagnosed and classified through voiding cystourethrography. RESULTS: Among the kidneys with reflux, there was agreement between the results of DMSA and IVU concerning the presence and the absence of scars in 82.4 percent of the cases. Based on the results obtained, IVU would have a sensitivity of 66.6 percent, specificity of 94.4 percent; accuracy of 82.5 percent; positive predictive value (PPV) of 90 percent and negative predictive value (NPV) of 79 percent, when compared with DMSA results. Our data also confirm the close relation between the reflux grade and the presence of renal scar, since 75 percent of the kidneys with grade IV and V reflux presented scars. In relation to the grading of nephropathy, in 78 percent of patients the classification of the scar by both methods was identical. The highest disagreement was verified in the group with segmental scar on DMSA, where 41.6 percent of the kidneys were classified as normal on IVU. CONCLUSION: The data obtained confirm that the scintigraphy with DMSA is essential in the investigation of patients with renal scar, and cannot be replaced by IVU, due to its low sensitivity and lower ability of satisfactory grading.