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UBC Theses and Dissertations

The contribution of pelvic muscle and ligament weaknesses to the development of stress urinary incontinence Yip, Clare


The symptoms of Stress Urinary Incontinence (SUI) and Pelvic Organ Prolapse (POP) are incited by strenuous activities, such as a valsalva maneuver, cough or lifting heavy objects. SUI is characterized by weakened bladder neck support and urine leakage. POP is characterized by the displacement of pelvic organs into the vaginal space. In women, the symptoms of SUI and POP often coexist, yet their relationship remains ambiguous. The POP-related defects that are relevant to SUI are unknown and are yet to be examined. Damages in pelvic floor muscles and cardinal and uterosacral ligaments are potential defects leading to SUI, since they are commonly found in SUI patients with POP symptoms. These defects can be objectively evaluated using Pelvic Muscle Strength test and Pelvic Organ Prolapse Quantification (POPQ) test. This study aims to explore the contribution of pelvic muscle and ligament weaknesses to the development of SUI by developing a biomechanical model of a female pelvic support system. The model simulates the behavior of a pelvic system during a valsalva maneuver, and it incorporates muscle strength score and POPQ points. Patient data were collected and implemented into the model to estimate the material parameters that describe the stiffness properties of the vaginal and ligament tissues for clinical patients. Using the model with parameters, the effect of varied degree of muscular and ligament weaknesses on the changes in the bladder neck and apical vaginal supports were assessed for the patients. The estimated vaginal and ligament parameters were shown to vary, illustrating the diverse material properties of pelvic tissues in individuals. In modeling, simulated conditions of defective muscles and ligaments were demonstrated to contribute to bladder neck and vaginal apex prolapse, consistent with the clinical conditions of POP; alternatively, simulated conditions of restored muscular and ligament supports were shown to help re-establish both bladder neck and vaginal apex supports. The results exhibit the impact of compromise of pelvic muscles and ligaments on the development of SUI and vaginal apex prolapse and suggest a mechanism of how pelvic muscles and vaginal apex rehabilitation impact SUI and vaginal apex supports in patients with coexisting POP symptoms.

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