^99mTechnetium dimercapto-succinic acid renal scintigraphy abnormalities in infants with sterile high grade vesicoureteral reflux

Purpose: Although vesicoureteral reflux associated with bacteriuria may cause renal scarring, sterile reflux is thought not to cause renal injury. We determined the incidence and associated characteristics of renal abnormalities using ^99mtechnetium(Tc) dimercapto-succinic acid (DMSA) renal scintigraphy in infants with high grade vesicoureteral reflux but no history of urinary tract infection. Materials and Methods: We retrospectively reviewed the results of ^99mTc-DMSA renal scintigraphy and renal ultrasonography performed during the first 6 months of life in infants with vesicoureteral reflux detected during the postnatal evaluation of prenatal hydronephrosis or sibling reflux screening. Those with a history of urinary tract infection, or evidence of ureteropelvic junction or bladder outlet obstruction were excluded from study. Results: Of the 28 male and 6 female infants who met study criteria vesicoureteral reflux was bilateral in 25 and unilateral in 9. Reflux grade was IV or V, II or III and I in 38, 18 and 3 of the 59 refluxing renal units, respectively. ^99mTc-DMSA renal scintigraphy revealed parenchymal abnormalities in 24 refluxing renal units (41%) in 22 patients (65%), of whom 19 (86%) were male and 15 (68%) had bilateral reflux. We noted differential uptake less than 40% with and without cortical defects in 10 and 7 refluxing units, respectively, and cortical defects only in 7. Of the 24 refluxing units with abnormalities 21 were associated with grade IV or V and 3 with grade II or III reflux. Ultrasound showed evidence of renal injury in only 7 of the 17 patients (41%) in whom ^99mTc-DMSA scintigraphy was abnormal. Conclusions: In our study the majority of infants with high grade reflux had decreased differential function and/or cortical defects. Parenchymal defects detected by ^99mTc-DMSA renal scintigraphy were often not identified by renal ultrasound. Therefore, ^99mTc-DMSA renal scintigraphy is especially useful for initially evaluating infants with high grade, sterile vesicoureteral reflux.