Ureteral Dilation Is a Clinically Significant Risk Factor for Urinary Tract Infections in Children With Prenatal Hydronephrosis: A Call to Revisit Practice Guidelines.

Abstract

Pediatric hydronephrosis is associated with an increased risk of UTIs. Clinical guidelines recommend continuous antibiotic prophylaxis for high-risk patients. In this study, we evaluated the association between hydroureteronephrosis and UTIs in infants. We performed a single-center retrospective risk analysis of patients with prenatal hydronephrosis from 2015 to 2024, including those with isolated hydronephrosis and megaureter. Demographic and imaging characteristics, including anteroposterior diameter, Society for Fetal Urology grade, and maximum ureter diameter on first postnatal ultrasound, were recorded. The primary outcome was time to UTI development. Landmark analysis and competing risk analysis with cause-specific Cox regression were used to identify HRs. Model performance was determined by the concordance index. Among 803 patients (median follow-up 23 months) included in landmark analysis, 29 developed a UTI. On initial ultrasound, 124 patients had hydroureteronephrosis and 451 patients had high-grade hydronephrosis. On cause-specific Cox regression, UTI was associated with sex, uncircumcised status, hydroureter (HR 1.15 per mm, 95% CI: 1.10, 1.21, <i>P</i> < .001), whereas hydronephrosis alone, by Society for Fetal Urology grade or anteroposterior diameter, was not significantly associated. Model performance showed concordance index 0.74 (optimism-adjusted 0.72). The presence of a hydroureter on initial postnatal ultrasound is a significant risk factor for UTI in infants with prenatal hydronephrosis, which supports the value of continuous antibiotic prophylaxis in this subgroup. By contrast, isolated hydronephrosis does not seem to justify the use of prophylaxis.