To evaluate the usefulness of congenital small kidney as a treatment indicator in children with primary vesicoureteral reflux (VUR).

Eighty-five children aged from 1 day to 108 months with primary VUR were analyzed retrospectively. The children were divided into 2 groups: a normal kidney group (n = 45) and a small kidney group (n = 44). VUR grade, age, sex, and bilaterality were compared between the 2 groups. As well, the incidence of spontaneous resolution/improvement in VUR and antireflux surgery were compared between the 2 groups.

No differences were observed in either presenting age bilaterality or follow-up period between the 2 groups. The most common grades were III in the normal kidney group (20/45) and IV in the small kidney group (22/44). Spontaneous resolution/improvement in VUR in the normal and small kidney groups occurred in 11 of 20 vs 0 of 6, 6 of 15 vs 1 of 22, and 2 of 10 vs 0 of 16 children with grades III, IV, and V, respectively. Antireflux surgery was performed in the normal and small kidney groups in 9 of 20 vs 6 of 6, 9 of 15 vs 21 of 22, and 8 of 10 vs 16 of 16 children with grades III, IV, and V, respectively. On multivariate analysis, renal size was a statistically significant indicator of an antireflux surgery after adjusting for age, bilaterality, and VUR grade.

Children with primary VUR accompanying small kidney show a lower opportunity of spontaneous resolution or improvement in VUR. Congenital small kidney could be an additional indicator for early surgical correction along with grade, age, sex, and laterality in children with primary VUR.