Dynamic Renal Scintigraphy in Children With Vesicoureteral Reflux and Suspected Coexisting Ureteropelvic Junction Obstruction

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Abstract
We evaluated whether findings on voiding cystourethrography suggesting ureteropelvic junction (UPJ) obstruction coexists with vesicoureteral reflux (VUR) are associated with parameters on dynamic renal scintigraphy that support significant obstruction. We reviewed records of 44 patients referred for scintigraphy after voiding cystourethrography performed at age 1 day to 9.4 years (mean 7 months, median 1.7 months) showed VUR and findings suggestive of UPJ obstruction (blockage of contrast material at the UPJ, contrast dilution in the renal pelvis, slow renal pelvic drainage). Results were correlated with Society for Fetal Urology hydronephrosis grade and ureteral morphology. Halftime was in the obstructive range (20 minutes or greater) for 7 of 47 kidneys (15%). The prevalence of a post-furosemide pelvicaliceal drainage halftime in the obstructive range increased with hydronephrosis grade (0% grade 1, 17% grade 2, 50% grade 3 to 4, p = 0.002) but did not vary with ureteral morphology (p = 0.08). In 12 of 38 cases (31%) where suspected UPJ obstruction was unilateral and a contralateral kidney was present differential uptake of the affected kidney was less than 45%. The prevalence of differential uptake less than 45% was higher in patients with than without ureteral dilatation (48% vs 12%, p = 0.02) but did not vary with hydronephrosis grade (p = 0.93). In children with VUR and suspected coexisting UPJ obstruction dynamic renal scintigraphy may support significant obstruction when hydronephrosis is at least moderate in degree or ureteral dilatation is present but is unlikely to do so if neither is observed.