Renal Doppler ultrasound in children with obstructive uropathy: Effect of intravenous normal saline fluid load and furosemide

Purpose: We studied the effect of hyperhydration with normal saline and furosemide on renal resistive index in children with obstructive uropathy. Materials and Methods: (99m)Technetium-mercaptoacetyltriglycine diuretic renography and Doppler ultrasound were done in 27 children (54 renal units) with unilateral or bilateral hydronephrosis. Doppler studies were performed at baseline, and after infusion of normal saline and administration of furosemide. Half-time drainage, considered the gold standard for the diagnosis of renal obstruction, was compared to resistive index. Results: There was a positive correlation between half-time and resistive index on both Doppler studies. With a resistive index of 0.70 as the critical value for predicting renal obstruction 82 versus 100% sensitivity (p < 0.006), 63 versus 94% specificity (p < 0.04) and 76 versus 98% overall accuracy (p < 0.0005) were obtained for Doppler studies at baseline and after induced diuresis, respectively. All children with false-positive results were younger than age 4 years. Conclusions: Doppler ultrasonography after hyperhydration with normal saline and furosemide is an accurate method for diagnosing renal obstruction in children. It is more sensitive, specific and accurate than baseline Doppler studies.