Renal Parenchyma Abnormalities in Infants With Dilating Vesicoureteral Reflux: Relation to Reflux Severity and Pressure at Onset

Abstract

Purpose: We used 99mtechnetium dimercapto-succinic acid scans in infants to determine the relation between renal deformities and severity of primary dilating reflux. We also used videourodynamics to analyze the association between detrusor pressure at onset of reflux and degree of renal changes. Materials and Methods: A total of 20 patients (15 males) 0.10 to 1.3 years old (median 0.75) with grade III to V reflux underwent conventional filling videourodynamics. 99mTechnetium dimercapto-succinic acid scans were done 6 months after the last febrile urinary tract infection (median age 0.58 years). Results: Nine males and 1 female had bilateral refluxing ureters, and 10 patients had unilateral reflux (grade III in 10, IV in 11 and V in 9). Among the 30 refluxing ureters renal changes were present in 19 kidneys (63%). Prevalence of renal changes according to reflux grade III, IV and V was 40%, 63% and 89%, respectively (p <0.02). Reflux occurred in 13 patients (21 ureters) with detrusor pressure less than 10 cm water and in 7 (9) at 30 to 70 cm water (median 39.5). Renal changes were significantly more common in low pressure, low volume refluxing ureters (84.6%) compared to ureters refluxing at higher volumes and low pressure (37.5%, p <0.02). At higher pressure reflux renal deformities occurred in 55.5% of refluxing ureters (5 of 9). Five patients had renal function impairment (mean creatinine for age 0.92 mg/dl, range 0.60 to 1.53). Conclusions: High grade reflux and reflux occurring in the first half of bladder filling at low pressure are risk factors for renal changes in this cohort of infants.