Design: Systematic review and diagnostic accuracy meta-analysis
Population: Children after first or recurrent UTI in 90 studies
Primary outcome: Accuracy of renal and bladder ultrasound for vesicoureteral reflux
Effect: First UTI: sensitivity 50% (95% CI 42 to 58), specificity 71% (62 to 78); recurrent UTI sensitivity 26%

A systematic review and meta-analysis in Pediatrics (1 October 2026), written to inform the 2026 American Academy of Pediatrics guideline on urinary tract infection in children aged 8 days to 5 years, pooled 90 studies of renal and bladder ultrasound against a reference standard for vesicoureteral reflux.

After a first UTI, ultrasound had a pooled sensitivity of 50% and specificity of 71%. Restricting to high-grade reflux (grades III to V) improved this only to 66% and 77%. After recurrent UTI, sensitivity fell to 26%. Certainty was low to moderate.

Ultrasound remains useful for finding structural anomalies such as hydronephrosis, duplex systems or scarring. But this review shows it cannot be used to decide that a child does not have reflux. Which children need a voiding cystourethrogram is a judgement the new guideline frames around recurrence and risk, not around a normal scan.

Do not treat a normal renal and bladder ultrasound as excluding vesicoureteral reflux.
Use ultrasound after a febrile UTI to look for structural anomalies, as before.
Consider a voiding cystourethrogram after recurrent febrile UTI or an abnormal scan, whatever the ultrasound shows about reflux.
Ask about bowel and bladder dysfunction, which drives recurrence and is treatable.

Why it matters

Many children are reassured on the strength of a normal ultrasound, which misses about half of reflux.

The statistics, in plain English

A sensitivity of 50% means ultrasound flagged reflux in only half the children who had it. A specificity of 71% means almost three in ten children without reflux had a scan that looked abnormal. Neither is good enough for a test used to decide on further imaging.