IMAGING STUDIES IN THE FOLLOW-UP OF CHILDREN WITH FIRST DIAGNOSED URINARY TRACT INFECTION: WHAT'S NEEDED? † 786

Abstract

Imaging studies are part of standard care following a first diagnosed urinary tract infection (UTI) in young children. Renal ultrasound (US), voiding cystourethrogram (VCUG), and dimercaptosuccinic acid (DMSA) or glucoheptonate renal scans aim to identify: unsuspected urinary tract anomalies or obstruction, vesicoureteral reflux (VUR), renal parenchymal involvement, and renal scarring. As part of an ongoing clinical trial evaluating oral vs. intravenous therapy for first time UTI, 179 children aged 1-24 mos. with fever (≥38.3° C) had a renal US and a DMSA or glucoheptonate scan within 48 hours of diagnosis, a VCUG one month following diagnosis, and a repeat scan six months later. A normal renal US was found in 157 (88%) patients, pelvocaliectasis and dilated renal pelvis in 14 (7.8%), megaureter in 5 (2.8%), duplicated collecting systems in 2 (1.1%), and a calculus in 1 (0.5%). VUR was as common in children with normal US as in those with an US showing dilatation of the upper urinary tract (50/154 vs. 7/17, NS). Renal scans performed at the time of infection showed parenchymal inflammation in 137 (77%) of 179 patients. A VCUG identified VUR in 75 (44%) of 172 patients -- grade I (18), grade II (27), grade III (25), and grade IV(5). To date, of the 134 patients who completed the 6-month follow-up, 90(67%) outcome scans were normal and 44 (33%) showed renal scarring. Scarring occurred in 44 (41%) of 108 patients who had evidence of acute pyelonephritis in the initial scan, and in none of 25 patients with normal scan at study entry. Results of US and DMSA scan at the time of presentation with UTI did not modify management. Current widespread use of prenatal US leads to identification of obstructions of the urinary tract in utero. Accordingly, selective (in patients with persistent fever or abdominal findings) rather than routine performance of US is recommended. A VCUG at one month and a DMSA scan six months later, were useful for identifying (1) patients with VUR who required prophylactic antimicrobial therapy, and (2) patients with renal scarring. The latter group may benefit from the early performance of urine culture in subsequent febrile episodes.