To determine the relationship between vaginal reflux (VR) and urinary tract infection (UTI) in female children aged <36 months.

A single center retrospective study was performed for 191 girls aged <36 months, with a diagnosis of febrile UTI, who underwent a voiding cystourethrography (VCUG) for assessment of vesicoureteral reflux (VUR) at Sanggye Paik Hospital. Fifty-one girls, who underwent VCUG for assessment of congenital hydronephrosis or renal pelvis dilatation, without a UTI, formed the control group. The correlation between the presence and grade of VR and UTI was evaluated.

The prevalence rate of VR was higher in the UTI (42.9%) than control (13.7%) group ( P <0.05), with a higher VR severity grade in the UTI (mean, 0.64) than control (mean, 0.18) group ( P <0.05). On subanalysis with age-matching (UTI group: n=126, age, 5.28±2.13 months; control group: n=22, age, 4.79±2.40 months; P =0.33), both VR prevalence (43.65% vs. 18.18%, P <0.05) and grade (0.65 vs. 0.22, P <0.05) remained higher in the UTI than control group. Presence and higher grade of VR were associated with UTI recurrence ( P <0.05). VR was correlated to urosepsis ( P <0.05). The renal defect rate of patients with VR (VR [+]/VUR [+]) was not different from that of patients without VR (74% vs. 52%, P =0.143) in the VUR group; however, it was higher than that of VR (+)/VUR (−) patients (74% vs. 32%, P =0.001). If a child with VR (+)/VUR (+) is exposed to a UTI, the risk of renal defect increases.

Occurrence of VR is associated with UTI recurrence and urosepsis in pediatric female patients.