Acute pyelonephritis and sequelae of renal scar in pediatric first febrile urinary tract infection.

To investigate the incidence of acute pyelonephritis (APN) and renal scarring in children with febrile urinary tract infection (UTI), 191 of 216 (88%) children with their first episode of UTI received (99m)Tc-dimercaptosuccinic acid renal single-photon emission computed tomography. They were investigated within 7 days of admission and were followed for 6 months. One hundred and six patients (49.1%) underwent a voiding cystourethrogram. The incidence of vesicoureteric reflux (VUR) in group I (</=1 year old) was 22%, group II (1-5 years old) 69%, and group III (5-17 years old) 44%. The overall incidence of APN in febrile UTI was 70% (male 66%, female 76%, P=0.110). Children had a higher incidence of APN than infants ( P<0.05 in group I vs. II and group I vs. III). Of patients with APN, 57% (35/61) showed renal scar formation. VUR was found in 31%(24/78) of children with APN and 58% (14/24) of children with renal scar. In addition, children with high-grade VUR were more susceptible to APN and scar formation than those with low-grade VUR ( P<0.05). Older children with a first febrile UTI had a higher incidence of APN than infants (</=1 year), and half of the children with APN developed a renal scar.