Dynamic urethral pressure profilometry pressure transmission ratio determinations after continence surgery: Understanding the mechanism of success, failure, and complications

Twenty-two women who had previously undergone continence surgery for the correction of stress urinary incontinence were evaluated with dynamic urethral pressure profilometry and had bladder-to-urethra pressure transmission ratios calculated. Eight of the subjects had recurrent or persistent genuine stress incontinence (group 1), seven had detrusor instability (group 2), and seven had normal continence and detrusor function (group 3). In addition, we evaluated ten subjects with detrusor instability but no previous surgery (group 4). There were clear and significant differences in pressure transmission ratios between the four groups. These differences suggest that subjects in group 1 have the same basic mechanisms of incontinence (ie, inefficient pressure transmission to the urethra as reflected by pressure transmission ratios less than 90%) as do neveroperated women with genuine stress incontinence. Subjects in group 2 had pressure transmission ratios that were significantly higher than those in either group 3 or 4. This supports the hypothesis that obstruction may play a role in post-continence surgery detrusor instability, but not in idiopathic detrusor instability. Group 2 subjects had pressure transmission ratios very close to the ideal of 100%. We postulate that continence procedures that consistently result in pressure transmission ratios close to 100% should have the greatest chance for success without inducing complications.