Renal and bladder ultrasound (RBUS) is a poor screening test for genitourinary abnormalities in children following a febrile urinary tract infection (UTI), researchers reported in Pediatrics (2014;133:e394-e403).

Caleb P. Nelson, MD, MPH, and colleagues at Harvard Medical School in Boston identified 2,259 patients younger than 60 months with had UTI has the indication for imaging. RBUS was reported as “normal” in 75% of cases. On voiding cystourethrogram (VCUG), any vesicoureteral reflux (VUR) was identified in 41.7% of cases, VUR grade greater than II in 20.9%, and VUR grade greater than III in 2.8%.

The sensitivity of RBUS for any abnormal findings on VCUG ranged from 5% (with a specificity of 97%) to 28% (with a specificity of 77%). Of 1,203 children aged 2-24 months imaged after a first febrile UTI, the positive predictive value of RBUS was 37%-47% for VUR grade higher than II and 13%-24% for VUR grade higher than III. The negative predictive value was 72%-74% for VUR grade higher than II and 95%-96% for VUR grade higher than III.

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Dr. Nelson’s team noted that the 2011 American Academy of Pediatrics guidelines state that RBUS should be performed after initial febrile UTI in a young child, with VCUG performed only if RBUS shows abnormalities. Based on their study findings, the researchers concluded that RBUS and VCUG should be considered complementary because they provide different but important information, the researchers concluded.