Continuous antibiotic prophylaxis in isolated prenatal hydronephrosis

Background: Prenatal hydronephrosis (PNH) is one of the most common congenital anomalies and can increase the risk of developing a urinary tract infection (UTI) in the first two years of life. Continuous antibiotic prophylaxis (CAP) has been recommended empirically to prevent UTI in children with PNH, but its use has been controversial.

Objective: We describe the incidence of UTI in children with isolated PNH of the renal pelvis without ureteral dilation. Our objective was to compare patients receiving and not receiving CAP and determine whether CAP is beneficial at preventing UTI in children with isolated PNH.

Study design: Children with confirmed PNH were enrolled between 2008 and 2020 into the Society for Fetal Urology Hydronephrosis Registry. Children with isolated dilation of the renal pelvis without ureteral or bladder abnormality were included. The primary outcome was development of a UTI, comparing patients who were prescribed and not prescribed CAP.

Results: In this cohort of 801 children, 76% were male, and 35% had high grade hydronephrosis (SFU grades 3-4). CAP was prescribed in 34% of children. The UTI rate among all children with isolated PNH was 4.2%. Independent predictors of UTI were female sex (HR = 13, 95% CI: 3.8-40, p = 0.0001), intact prepuce (HR = 5.1, 95% CI: 1.4-18, p = 0.01) and high grade hydronephrosis (HR = 2.0, 95% CI: 0.99-4.0, p = 0.05; Table) on multivariable analysis. For patients on CAP, the UTI rate was 4.0% compared to 4.3% without CAP (p = 0.76). The risk of UTI during follow-up was not significantly different between patients who received CAP and patients who were not exposed to CAP; adjusting for sex, circumcision status and hydronephrosis grade (HR = 0.72, 95% CI: 0.34-1.5, p = 0.38). In sub-group analysis of patients at higher risk of UTI (uncircumcised males, females and high grade hydronephrosis), CAP use was not associated with a statistically significant reduction in UTI.

Conclusions: The overall UTI rate in children with isolated PNH is very low at 4.2%. In the overall population of patients with isolated PNH, CAP was not associated with reduction in UTI risk, although the limitations in our study make characterizing CAP effectiveness difficult. Clinicians should consider risk factors prior to placing all patients with isolated PNH on CAP.