Risk Factors for Recurrent Urinary Tract Infection in Infants With Vesicoureteral Reflux During Prophylactic Treatment: Effect of Delayed Contrast Passage on Voiding Cystourethrogram

ObjectivesTo investigate the risk factors for recurrent urinary tract infection (UTI) in infants with vesicoureteral reflux (VUR) because little is known regarding the risk factors for breakthrough infection.MethodsWe compared children with infantile VUR with (20 boys, mean age 2.7 months) and without (20 boys and 4 girls, mean age 4.7 months) recurrent UTI. The factors compared included sex, timing of UTI episode, degree and bilaterality of the reflux, hydronephrosis, renal scar, associated congenital anomalies, voiding dysfunction, and delayed ureteral excretion of refluxed contrast on the voiding cystourethrogram.ResultsUnivariate Cox survival-time regression analysis showed that a younger mean age at the first UTI, bilateral reflux, and grade 4-5 VUR and hydronephrosis on the initial ultrasound scan significantly increased the risk of recurrent UTI (P < .05 each). On multivariate analysis, high-grade (P = .009) and bilateral (P = .016) VUR were independently associated with an increased risk of recurrent UTI. Of the infants with and without recurrent UTI, 80% and 0%, respectively, presented with high-grade VUR, as shown by delayed contrast passage on the voiding cystourethrogram. A urodynamic study of 11 infants with recurrent UTI showed decreased bladder capacity in 2 infants and a larger residual volume in 1 infant.ConclusionsDuring the first year after birth, high-grade and bilateral VUR significantly increased the risk of recurrent UTI. Delayed contrast passage on the voiding cystourethrogram was significantly associated with an increased risk of recurrent UTI.