[Preoperative cystometric analysis of benign prostatic hyperplasia--special reference to the natural history and postoperative outcomes].

Four hundred and thirty-seven patients with benign prostatic hyperplasia selected for elective prostatectomy underwent preoperative cystometry. Of these patients 263 (60.2%) had bladder instability, who tended to be more irritative and more obstructive in their preoperative objective assessment than the others. Forty-seven patients (12.5%) revealed vesical denervation supersensitivity, of these patients all but one had bladder instability. Significant correlation was found between occurrence of the bladder dysfunction and the severity of obstruction. The occurrence of both bladder dysfunction developed with age. Four hundred and fourteen patients (94.7%) had successful outcome in voiding postoperatively, but elderly patients with low bladder compliance and severe emptying failure tended to need several months in their recovery. Postoperative incontinence was found in 100 patients (22.9%) with high incidence of preoperative bladder instability in the early phase, but was reduced in most cases 6 months later. Eighteen prolonged incontinent cases showed high incidence of low bladder capacity and low compliance with instability at preoperative cystometry. In these cases, the incidence of elderly patients was higher than that of dry cases. It is concluded that most of these bladder dysfunction is secondary to the infravesical obstruction which depends upon severity and duration of the disease, but aging also appears to play a role in its appearance. We assume that detrusor instability represents a kind of compensation for infravesical obstruction, and that the development of denervation supersensitivity indicates that the bladder damage is severely progressing.