There is still debate regarding the exact underlying pathophysiology of genital tract prolapse. In recent times, much has been done to investigate the neurogenic origins of pelvic floor dysfunction. Although connective tissue has been implicated in vaginal prolapse, comparatively fewer studies have been performed to examine its role in prolapsed.
1. Pelvic connective tissues play a significant role in the pathogenesis of vaginal prolapse.
2. Different mechanisms operate in younger (pre-menopausal) versus older (post-menopausal) women suffering from vaginal prolapse
1. To develop a method of biomechanical assessment for biological soft tissues that may possess significant plastic properties.
2. To measure biomechanical and biochemical properties of vaginal connective tissue and their influence on vaginal prolapse.
3. To determine whether connective tissue differences are present between pre- and post-menopausal women with prolapse.
4. To relate the findings to the clinical setting.
In this study, vaginal connective tissue in women with prolapse was examined biomechanically and biochemically. By assessing the different aspects of the connective tissue, a thorough investigation of its properties may be ascertained. Previously, most investigators have only analysed biochemical qualities. To date, no biomechanical testing on human vaginal tissue has been reported.
For this study, vaginal tissues from pre- and post-menopausal women with prolapse were collected during surgical repair. Ethics committee from Logan and Gold Coast Hospitals approved tissue collection at time of surgery. Informed consent was obtained from the woman prior to surgery.
The initial study proposal included comparative studies of tissue from control women (young women and women without prolapse). However, Ethics Committee from the John Tonge Forensic Centre denied approval for the study. As a result, only tissue from women suffering from vaginal prolapse was collected and studied.
Most biomechanical experimental models are designed for testing of ligaments and bone. Previous models for testing skin were considered non-physiological by the author as this involved testing the tissue to failure. In other words, loads were applied to the tissue until rupture occurred. For the purposes of this thesis, a model was required to test vaginal tissue under more physiological stress and strain. An experimental protocol was designed to measure elastic properties of non-linear visco-elastic and plastic connective tissue under a wide range of mechanical loading. This experimental design allowed small stiffness changes of the tissue during the mechanical loading to be detected.
It was found that vaginal tissue from post-menopausal women had high elastic modulus compared to pre-menopausal women. This change may be age-related as the higher elastic modulus merely indicates that the tissue is stiffer and less elastic. That is for a given tension increase, the tissue stretches less. This does not indicate that the post-menopausal tissue is weaker and there were no significant differences in other biomechanical parameters.
Biochemically, hydroxyproline was extracted from vaginal tissue and quantified. Hydroxyproline was used to quantify collagen content. There was a significant difference in pre and post-menopausal hydroxyproline content. The mean value of hydroxyproline was higher in pre-menopausal women.
Thus, although the collagen content is higher in pre-menopausal women, functionally the tissue behaves in a similar fashion to that of post-menopausal women with less collagen in the tissues. That is, both groups of women presented with symptomatic prolapse and biomechanical analysis demonstrated only age-related changes in elasticity.
A hypothesis of inherent potential weakness of pelvic connective tissue is proposed to explain the different findings in pre and post-menopausal women and the varying presentations seen at clinical practice. In view of this hypothesis, a review of surgical management is suggested as current mainstream surgical practice utilises the woman's fascia for prolapse repair. For pre-menopausal women with significant vaginal prolapse, adjuvant augmentation of the fascia is proposed.
However, further research is required for the assessment of the role of connective tissue in vaginal prolapse.