High-pressure bladder: an underlying factor mediating renal damage in the absence of reflux?

Objective To assess urodynamic studies of children with nonrefluxing pyelon ephritis, investigate the possible connection between renal damage (as appr oximate to 40% of children with febrile urinary tract infections and no evi dence of vesico-ureteric reflux have irreversible renal cortical scarring) and lower urinary tract dysfunction, to test the hypothesis that bladders w ith high storage and voiding pressures may be the cause of renal damage in these patients. Patients and methods The clinical records and urodynamic studies of 52 chil dren (46 girls and six boys, mean age 6.6 years) with febrile urinary infec tions, no evidence of reflux and photopenic areas on renal scintigraphy wer e evaluated retrospectively. Each child was evaluated by urinary ultrasonog raphy, a voiding cystogram, Tc-99m-dimercaptosuccinic acid (DMSA) scan and urodynamic studies. The storage phase of the urodynamic study was divided i nto two equal segments to consider the filling variables of each. During th e emptying phase, voiding pressures and voiding pressures with reference to peak detrusor contraction were evaluated. Results Despite no child having reflux, the DMSA scans showed bilateral ren al scarring in 39 (75%) and unilateral scarring in the remaining children. Forty eight (93%,) children had abnormal urodynamic values: high filling pr essures (34), high-pressure uninhibited contractions (32), high voiding pre ssures (31) and discoordinated voiding (28). The cystometric bladder capaci ty was lower than the expected bladder capacity (-75 mL) in 82% of the pati ents: in only four patients were the urodynamics considered normal. Conclusions Most children with renal scarring and no reflux had lower urina ry tract dysfunction. Common findings include high storage and voiding pres sures, and discoordinated voiding. These findings suggest that abnormal bla dder dynamics play a role in the development of renal scars that occur in t he absence of reflux.