Urodynamic evaluation of the human bladder response to an increase in outlet resistance

Aim. We prospectively evaluated the response of the human bladder to a chronic increase in urethral resistance according to the indices of pressure, volume flow rate, total (external) bladder work, and maximum and average detrusor power. Methods. Six men with incontinence after radical prostatectomy were evaluated urodynamically before and 3-6 months after undergoing a bulbourethral sling procedure. Results. None of the men suffered from significant obstructive or irritative voiding symptoms preoperatively. Urodynamic evaluation showed postoperative increases in both average detrusor pressure and pressure at maximum flow, but there were no significant changes in voided volume, void time, or postvoid residual urine volume. Maximum detrusor power, average detrusor power, and total (external) bladder work were all significantly increased. Conclusion. These data confirm that the human bladder possesses a functional reserve, which is elicited by an increase in urethral resistance.