Biomechanics of Urinary Stress Incontinence Surgery – Theory of the Non-Permanently Acting Suburethral Supportive Structure

Abstract

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.

Functional anatomy of pelvic floor

“…The pubo-vaginal muscle action represents the active continence value of "fibrous skeleton" but concerning the ptosis it is quite independent. An other divergent aspect compared with Ashton Miller and de Lancey theory is that regarding on which part of the urethra the abdominal pressure and the pubo-visceral muscle action exert their power (40); also in past time frequent debates happened regarding Enhorming G. theory ( 42) on pressure percentile fall on the abdominal portion of the urethra compared to that one on the bladder (50% according to some, 75% to others; see discussion in 35, pages 734-35) and regarding the urethral bend on perineal body. Recent interesting studies still confirm those discrepances (41) and confirm the existence of cases in which normal continence was present also when all portions of urethra laid below the perineal body (in contrast of Enhorming theory).…”

Pleated colposuspension: Our modification of Burch colposuspension

“…We believe that satisfactory urethral mobility is crucial for achievement of post-operative continence and avoiding urine retention. According to the Lazarevski's Theory,[11] the non-permanent sub-urethral support should be active only during the maximal effort and for this to occur, the principal requirement is a mobile urethra.…”

Reflections in light of the recently published urethral hanging theory of female stress urinary incontinence

“…This is analogous to blowing up a rubber balloon when the initiation of expansion may be nearly impossible. Pascal's principle of fluid mechanics postulates that when the radius (r) of the meatus internus widens, the outflow‐distending force (Fd) increases abruptly, which is described as follows in Pascal's formula: Fd = (aLPP + Pdet) × pi × r2; (aLPP = abdominal leak point pressure, Pdet = detrusor pressure). Additionally the length of the functional urethra is shortened in proportion to the depth of the funnel.…”