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

To assess urodynamic studies of children with nonrefluxing pyelonephritis, investigate the possible connection between renal damage (as approximately 40% of children with febrile urinary tract infections and no evidence of vesico-ureteric reflux have irreversible renal cortical scarring) and lower urinary tract dysfunction, to test the hypothesis that bladders with high storage and voiding pressures may be the cause of renal damage in these patients.

The clinical records and urodynamic studies of 52 children (46 girls and six boys, mean age 6.6 years) with febrile urinary infections, no evidence of reflux and photopenic areas on renal scintigraphy were evaluated retrospectively. Each child was evaluated by urinary ultrasonography, a voiding cystogram, 99mTc-dimercaptosuccinic acid (DMSA) scan and urodynamic studies. The storage phase of the urodynamic study was divided into two equal segments to consider the filling variables of each. During the emptying phase, voiding pressures and voiding pressures with reference to peak detrusor contraction were evaluated.

Despite no child having reflux, the DMSA scans showed bilateral renal scarring in 39 (75%) and unilateral scarring in the remaining children. Forty-eight (93%) children had abnormal urodynamic values: high filling pressures (34), high-pressure uninhibited contractions (32), high voiding pressures (31) and discoordinated voiding (28). The cystometric bladder capacity was lower than the expected bladder capacity (- 75 mL) in 82% of the patients; in only four patients were the urodynamics considered normal.

Most children with renal scarring and no reflux had lower urinary tract dysfunction. Common findings include high storage and voiding pressures, and discoordinated voiding. These findings suggest that abnormal bladder dynamics play a role in the development of renal scars that occur in the absence of reflux.