Study: Ultrasound should be first-line approach for pediatric UTI

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First-line renal ultrasound of febrile children with a first urinary tract infection (UTI) could provide data to obviate invasive voiding cystourethrography (VCUG), according to a study published in this month's Pediatric Infectious Disease Journal.

Belgian researchers conducted a prospective clinical and imaging study of 209 children (median age, 10 months) presenting with a clinically proven first UTI between July 2006 and July 2008 to evaluate multiple parameters including the diagnostic performance of renal ultrasound.

Experts have debated the utility of imaging studies for children with UTI, offered Khalid Ismaili, MD, PhD, from Hopital Universitaire des Enfants-Reine Fabiola in Brussels, Belgium, and colleagues. Up to 40 percent of children undergoing VCUG may have vesicoureteral reflex (VUR), and 60 to 80 percent of patients with VUR may have recurrent infection within 18 months of presentation, explained Ismaili et al.

However, physicians have not yet conclusively determined that VUR predisposes patients to UTI and renal scarring. Furthermore, renal scarring may occur in the absence of demonstrable reflux.

The standard of care at the author’s institution required an ultrasound during hospitalization and VCUG one month after the first UTI. The researchers used the imaging data to assess the diagnostic performance of renal ultrasound to detect VUR against the standard VCUG.

The 209 renal ultrasound studies did not show any structural abnormality in 81 percent of patients, offered Ismaili and colleagues. VCUG detected evidence of VUR in 25 percent of children, and 85 percent of these cases were classified as low-grade.

Thirty-four percent of patients with VUR on VCUG had an abnormal ultrasound, which the researchers attributed to ultrasound’s low sensitivity for low-grade reflux. They pointed out that ultrasound suggested abnormal pathology in 88 percent of patients with grade IV-V VUR.

Ismaili et al offered, “The overall performance of renal ultrasound as a diagnostic test to detect significant congenital abnormalities of the kidney and/or urinary tract excluding low-grade VUR was excellent; the sensitivity was 97 percent and specificity 94 percent.”

The researchers continued, “With a vast majority of children with UTI having a low risk of recurrence, as shown in our study, a major question is the extent to which these children are submitted to unnecessary and invasive investigations … [W]hen ultrasound examination was normal in children after a first UTI with fever, the risk of missing a significant renal abnormality was extremely low.”

Ismaili and colleagues said the recurrence rate among patients with low-grade VUR is similar to that of patients without VUR.

Ultimately, Ismaili and colleagues concluded, “Ultrasound should remain the first-line examination in febrile children with a first UTI. The presence or absence of abnormal ultrasound represents the key for deciding about VCUG studies.”