Diagnostic yield of urinary tract ultrasound in children following a first urinary tract infection: a retrospective cohort study

BACKGROUND: Urinary tract ultrasound (US) is widely recommended following a first urinary tract infection (UTI) in children to detect congenital anomalies of the kidney and urinary tract (CAKUT). However, its routine use has been questioned, given the limited diagnostic yield of US for certain anomalies. OBJECTIVE: To assess the diagnostic yield of urinary tract US after a first UTI and its impact on clinical management. MATERIALS AND METHODS: This retrospective study included 1,460 children who underwent urinary tract US following a first UTI between January 2014 and December 2024. Children were stratified by age and classified into five diagnostic categories based on US findings, with follow-up data reviewed to assess final diagnoses. RESULTS: Most children were classified with normal US (74.3%). CAKUT was identified in 6.9%, while CAKUT with dilation was detected in 3.5%. Vesicoureteral reflux (VUR) was the most common CAKUT with dilation (1.64%). Most children with VUR (89.7%) were ≤24 months old. CAKUT with dilation was more common in males (P=0.003) and infants aged 0-6 months (P=0.04), representing 35.6% of the study population. Despite a normal initial US, 34 additional cases of VUR were identified after recurrent UTI. CONCLUSION: Routine US after a first UTI in all children detects few clinically relevant abnormalities, does not reliably guide the need for reflux studies, and presents a burden for the health system; therefore, selective imaging strategies should be considered. Our findings support the consideration of a more selective imaging strategy. A two-tier imaging approach may be warranted for infants younger than 6 months and all male children following a first UTI, and children with recurrent UTIs.