Post-pyelonephritic renal scars are not associated with high voiding pressures

The aim of this study was to evaluate whether renal scars and vesicoureteral reflux (VUR) are associated with bladder dysfunction in children after first clinical pyelonephritis.

Sixty-four children were evaluated with urodynamics and voiding cystourethrography at a median of 8 weeks after their first episode of clinical pyelonephritis. All patients had ultrasonography and dimercaptosuccinic acid (DMSA) scintigraphy during the infection. After 2 years, DMSA scintigraphy was repeated in 58 patients. Re-infections were recorded.

Overactive detrusor was found in 27 (42%) patients. There was no significant difference in the incidence of overactive detrusor between boys and girls. The maximal voiding pressure was higher in boys (median 92.5, range 48-191 cmH(2)O) than in girls (median 82, range 37-150 cmH(2)O) (P=0.0117). Thirty-one (48%) patients had renal defects in scintigraphy during the infection. Ultimately, 12 patients (21%) developed renal scars; 11 patients (17%) had VUR. Renal defects in DMSA scintigraphy and the presence of VUR were not associated with overactive detrusor or high voiding pressures.

Overactive detrusor is a common finding after first episode of pyelonephritis. The dysfunction may explain the development of urinary tract infections in some children. There were no differences in the incidence of overactive detrusor or voiding pressures in patients with and without VUR, or in those with and without renal defects on DMSA scintigraphy. Urodynamic study is not a primary investigation in pyelonephritic children.