Incidence of abnormal imaging and recurrent pyelonephritis after first febrile urinary tract infection in children 2 to 24 months old

Abstract

Purpose: The AAP (American Academy of Pediatrics) no longer recommends voiding cystourethrogram in children 2 to 24 months old who present with a first urinary tract infection if renal-bladder ultrasound is normal. We identified factors associated with abnormal imaging and recurrent pyelonephritis in this population.

Materials and methods: We retrospectively evaluated children diagnosed with a first episode of pyelonephritis at age 2 to 24 months using de-identified electronic medical record data from an institutional database. Data included age at first urinary tract infection, gender, race/ethnicity, need for hospitalization, intravenous antibiotic use, history of abnormal prenatal ultrasound, renal-bladder ultrasound and voiding cystourethrogram results, urinary tract infection recurrence and surgical intervention. Risk factors for abnormal imaging and urinary tract infection recurrence were analyzed by univariate logistic regression, the chi-square test and survival analysis.

Results: We identified 174 patients. Of the 154 renal-bladder ultrasounds performed 59 (38%) were abnormal. Abnormal prenatal ultrasound (p = 0.01) and the need for hospitalization (p = 0.02) predicted abnormal renal-bladder ultrasound. Of the 95 patients with normal renal-bladder ultrasound 84 underwent voiding cystourethrogram. Vesicoureteral reflux was more likely in patients who were white (p = 0.003), female (p = 0.02) and older (p = 0.04). Despite normal renal-bladder ultrasound, 23 of 84 patients (24%) had dilating vesicoureteral reflux. Of the 95 patients with normal renal-bladder ultrasound 14 (15%) had recurrent pyelonephritis and 7 (7%) went on to surgical intervention.

Conclusions: Despite normal renal-bladder ultrasound after a first pyelonephritis episode, a child may still have vesicoureteral reflux, recurrent pyelonephritis and the need for surgical intervention. If voiding cystourethrogram is deferred, parents should be counseled on these risks.

Keywords: (99m)technetium-dimercaptosuccinic acid; DMSA; RBUS; UTI; VCUG; VUR; kidney; pyelonephritis; renal-bladder ultrasound; ultrasonography; urinary tract infection; urinary tract infections; vesico-ureteral reflux; vesicoureteral reflux; voiding cystourethrogram.

Figure 1

Age distribution at diagnosis of first episode of pyelonephritis.

Figure 2

Kaplan-Meier curve for febrile UTI recurrence after the first diagnosis of pyelonephritis.

Figure 3

VCUG results in patients with normal RBUS after the first diagnosis of pyelonephritis.