Mechanism of postoperative urinary continence

Stress incontinence used to be attributed mostly to urethral hypermobility, and consequently most surgical techniques focused on the region of the bla dder neck and proximal urethra. This article reviews our knowledge about th e mechanism of postoperative urinary continence based on anatomic, imaging and urodynamic studies. Reduction of urethral mobility, as measured by cott on swab testing or imaging studies, is not the only reason why continence s urgery succeeds. Imaging techniques are of limited value for elucidating th e continence mechanism because radiologic landmarks and criteria are not re producible. Urodynamically, the increased pressure transmission after succe ssful continence surgery is attributed to the retropubic repositioning of t he urethra, its compression against the anterior vaginal wall, and improved transmission of intraabdominal pressure during stress. The role of the 'fu nctional' urethral obstruction remains to be studied. In incontinent patien ts with hypermobility of the bladder neck and proximal urethra continence c an be achieved by surgical correction. However, stress incontinence is poss ible in the absence of urethral hypermobility, and standard surgical techni ques can fail to restore continence in these patients.