Renal parenchymal damage in male infants with high grade vesicoureteral reflux diagnosed after the first urinary tract infection

Purpose: Vesicoureteral reflux during infancy is found mainly in males, and it is of high grade and often bilateral. The higher predominance of male infants is reported in series when the reflux is diagnosed prenatally and when it is detected after urinary tract infection. Renal parenchymal damage may already be present at birth before any episode of urinary tract infection or acquired after a febrile urinary tract infection. We evaluate the incidence of renal damage in a large series of male infants with high grade vesicoureteral reflux diagnosed after the first urinary tract infection. Materials and Methods: We reviewed the medical and radiological records of 141 consecutive male infants 3 weeks to 1 year old (mean age 5.8 months) who were diagnosed with high grade (III to V) vesicoureteral reflux on voiding cystourethrography during 1984 to 2000 following hospitalization for the first febrile urinary tract infection. A total of 127 (90%) patients underwent (99)technetium dimercapto-succinic acid scan to evaluate renal damage 3 to 6 months after the initial infection. Results: Vesicoureteral reflux was unilateral in 46 infants and bilateral in the remaining 95, comprising 236 ureters. Reflux was grade III in 79 ureters, IV in 114 and V in 43. Renal parenchymal damage was detected in 56 (44%) of the 127 infants on dimercapto-succinic acid scan, and was bilateral in 18 and unilateral in the 38, representing 74 renal refluxing units. Renal damage was mild (greater than 40% uptake) in 47 units, moderate (less than 40% and greater than 20% uptake) in 22 U and severe (less than 20% uptake) in 5 U. Conclusions: This study shows that nearly half of the male infants with high grade reflux who present with the first febrile urinary tract infection have renal parenchymal damage. This high incidence of renal damage may be explained by the coexistence of the 3 risk factors of gender, urinary tract infection and high grade vesicoureteral reflux.