Guidelines for urinary tract infections and antenatal hydronephrosis should be gender specific.

Objective: Febrile urinary tract infections (UTIs) may be associated with long-term renal damage. Our goal was to identify risk factors for future UTIs in children who had voiding cystourethrography (VCUG) as a part of an antenatal hydronephrosis (ANH) assessment or after a febrile UTI.

Methods: We conducted a cohort study based on the medical records of children aged 0-24 months who underwent a VCUG between January 2004 and December 2011 and had at least six months of follow-up. The incidence of future UTIs was assessed.

Results: We included 285 children: 176 had a primary UTI and 109 had ANH. We recorded 28 UTIs during the follow-up period, and the risk was 12.5% after a primary UTI and 5.5% after an ANH (p = 0.049). Multivariate analysis showed no risk difference was found between the groups. Females had a greater risk of febrile UTIs (hazard ratio 3.3, 95% confidence interval 1.03-9.2, p = 0.04), but the UTI risk did not differ between children with or without VURs.

Conclusions: Female infants were at greater risk of febrile UTIs, regardless of the presence of VUR, VUR degree, ANH or a previous UTI. Clinical guidelines for UTI and ANH assessment should preferably be gender specific.