The clinical significance of the reflux producing intrinsic bladder pressure and bladder volume in reflux and reflux nephropathy.

In 60 patients with vesicoureteral reflux (VUR) primarily diagnosed on a conventional voiding cystourethrography, the VUR was revisited more precisely by way of a video pressure flow VCU via suprapubic catheters with special emphasis on the reflux producing intrinsic bladder pressure (RPBP) and the reflux producing bladder volume (RPBV). The VUR was subdivided into a low pressure reflux group (RPBP less than or equal to 35 cm H2O) and a high pressure reflux group (RPBP greater than 35 cm H2O), and into a low bladder volume reflux group (RPBV less than or equal to 50% of bladder capacity or 150 ml) and a high bladder volume reflux group (RPBV greater than 50% of bladder capacity or 150 ml). Reflux grade II or less was defined as low grade reflux and reflux higher than grade II was defined as high grade reflux. Thirty-three units refluxed at low pressures and 17 units at high pressures. In 33 units the reflux occurred at a low bladder volume and 17 at a high bladder volume. The pressure at the reflux was equally distributed in the low and the high grade reflux group. However, in the high grade reflux group low pressure, low bladder volume reflux was accompanied by a significantly higher incidence of nephropathy compared to the high pressure high volume reflux group. Furthermore, the low volume reflux group showed a significantly higher incidence of nephropathy compared to the high bladder volume reflux group. This report substantiates the coincidence between severity of reflux nephropathy and exposure to reflux and stresses the importance of a thorough evaluation of VUR patients including measurement of the reflux producing intrinsic bladder pressure and bladder volume.