Clinical characteristics of primary vesicoureteral reflux in infants: multicenter retrospective study in Japan.

PURPOSE: We evaluate clinical characteristics of primary vesicoureteral reflux in infants in a multicenter study in Japan with special reference to the relation of renal parenchymal damage to urinary tract infection and gender.

MATERIALS AND

METHODS

Infants younger than 1 year old with primary vesicoureteral reflux were recruited from 14 hospitals during the 3-year registration period beginning in January 1996 and ending in December 1998. Various clinical parameters as well as renal parenchymal lesion on dimercaptosuccinic acid scintigraphy were evaluated.

RESULTS

Of 356 infants enrolled 296 (83%) were male and 60 (17%) were female. In 85% of infants presenting symptom was febrile urinary tract infection. There were 204 bilateral (57%) and 152 unilateral (43%) cases. Reflux was bilateral in 56% of males versus 65% of females, and high grade (grades IV and V) in 58% of males versus 55% of females. Diffuse parenchymal lesion was similarly noted in infants with or without prior urinary tract infection (38% and 46%, respectively) and was more often noted in male than in female infants (42% versus 25%).

CONCLUSIONS

Despite the current use of screening prenatal ultrasound, many infants are still diagnosed as having vesicoureteral reflux only after the occurrence of urinary tract infection. The greater severity of renal parenchymal lesion in male infants combined with similar incidence of diffuse parenchymal lesion in those with or without prior infection suggests preexisting congenital abnormalities in the male refluxing kidney.