Biomechanics of urinary stress incontinence surgery--theory of the non-permanently acting suburethral supportive structure.

This biochemical study of the lower urinary tract as it relates to urinary continence and incontinence is based on the morphotopographic results of radiological, autopsy and surgical investigations in the period 1966-1968. The process of urinary continence is simply explained by the application of universal hydromechanical laws, which demonstrated that continence during straining results from compression of the urethra over a suburethral resistant structure. Compression occurs during dorsocaudal physiologic displacement of the urethrovesical complex in conditions of increased intra-abdominal pressure. The theory of a non-permanently acting suburethral support is based on these results and represents the essential principle of urinary stress incontinence surgery, namely, that surgery should create a suburethral resistance over which the proximal urethra is compressed during increased intra-abdominal pressure. Such suburethral resistance may be created via the vaginal or the abdominal routes, using autogenous or heterogeneous tissue. A critical analysis of different surgical techniques and how they achieve the demands of this theory is presented. In this context two orginal surgical procedures incorporating the best biomechanical features are elaborated: slinglike colposuspension via the abdominal route, and suburethral duplication of the anterior vaginal wall by the vaginal route. The aim of this paper is to present the biomechanical study of urethrovesical phenomena playing a role in urinary continence and the pathogenesis and surgery of stress incontinence in light of our theory. Our personal experience with 1,836 surgical procedures between 1968 and the end of 1997, encompassing 1,056 slinglike colposuspensions and 780 suburethral duplications of the vagina, gives practical support to our concepts.