Avoidance of voiding cystourethrography in infants younger than 3 months with urinary tract infection and normal renal ultrasound.

BACKGROUND AND OBJECTIVE

Urinary tract infection (UTI) represents the most common bacterial infection in infants, and its prevalence increases with the presence of high-grade vesicoureteral reflux (VUR). However, voiding cystourethrography (VCUG) is invasive, and its indication in infants <3 months is not yet defined. This study aims to investigate, in infants aged 0-3 months, if the presence of versus non- bacteria and/or normal or abnormal renal ultrasound (US) could avoid the use of VCUG.

METHOD

One hundred and twenty-two infants with a first febrile UTI were enrolled. High-grade VUR was defined by the presence of VUR grade ≥III. The presence of high-grade VUR was recorded using VCUG, and correlated with the presence of /non- UTI and with the presence of normal/abnormal renal US. The Bayes theorem was used to calculate pretest and post-test probability.

RESULTS

The probability of high-grade VUR was 3% in the presence of urinary infection. Adding a normal renal US finding decreased this probability to 1%. However, in the presence of non- bacteria, the probability of high-grade VUR was 26%, and adding an abnormal US finding increased further this probability to 55%.

CONCLUSIONS

In infants aged 0-3 months with a first febrile UTI, the presence of and normal renal US findings allow to safely avoid VCUG. Performing VCUG only in infants with UTI secondary to non- bacteria and/or abnormal US would save many unnecessary invasive procedures, limit radiation exposure, with a very low risk (<1%) of missing a high-grade VUR.