Urodynamics in prostatism. III. Prognostic value of medium-fill water cystometry.

The influence of preoperative cystometric findings on the post-surgical outcome in prostatism was examined in a prospective study comprising 139 consecutive patients. A blinded study design was used, including an entirely non-urodynamic selection procedure for prostatic surgery. In addition an extensive urodynamic investigation was carried out including: spontaneous uroflowmetry, medium-fill water cystometry and pressure-flow study combined with stop-flow test. All patients were re-evaluated 6 months postoperatively, both symptomatologically and urodynamically. The patients were classified in three groups according to the preoperative detrusor function: normal, overactive in the standing position and overactive in the supine position. No significant urodynamic nor symptomatologic differences were shown, neither pre- nor postoperatively. Nor did the subjective outcome differ between the groups. Demonstration of postoperative (persistent) detrusor instability was associated with an unfavourable subjective outcome. While residual urine had no predictive importance, a preoperative maximum cystometric capacity less than 300 ml appeared to indicate postoperative failure. Significant association was found between urge and detrusor instability. In conclusion, cystometry is not worthwhile in the preoperative work-up in prostatism.