UNS: Collaborative Research: Impact of Pregnancy on the Mechanics of Vaginal Tissue

骨盆底疾病（PFDs）包括许多医学病症，包括压力性尿失禁和大便失禁以及盆腔器官脱垂。虽然不经常讨论，但这些情况非常常见，超过50%的经产妇女在其一生中有一定程度的PFD，11%的妇女需要手术。这些疾病严重改变了妇女的生活质量，往往导致孤立和抑郁。对于不完全熟悉女性盆腔内部解剖的人来说，在这些疾病的发展中，阴道可能并不比直肠或尿道更重要。然而，阴道是尿道、膀胱、子宫和直肠的主要支撑结构。反过来，阴道由肌肉和结缔组织的组合支撑。对阴道和/或其支持性肌肉和组织的直接损伤会损害其他盆腔器官的功能。因此，在分娩和阴道分娩过程中过度拉伸和撕裂阴道是PFDs发展的诱发因素，这并不奇怪。然而，目前尚不清楚怀孕期间阴道组织中发生的结构和机械变化使妇女易于发生PFDs。该合作项目旨在首次描述处女和妊娠大鼠阴道组织中拉伸诱导损伤和撕裂传播的机制。将进行一套全面的环测试，以确定组织的功能作用？的成分（胶原蛋白，弹性蛋白和平滑肌细胞）对阴道的主动和被动力学。将进行平面双轴测试以研究撕裂扩展过程。这些测试的结果将指导开发一种新的本构模型，该模型将捕获阴道组织的主动和被动机械响应，包括拉伸引起的损伤。本构模型将被实施到一个有限元代码，特别是开发来模拟阴道组织的损伤和撕裂传播。为了进行确认，将使用三维体内实验数据，这些数据是通过在最先进的7 T micro-MRI中进行模拟出生损伤的充气测试收集的。

Pelvic floor disorders (PFDs) encompass a number of medical conditions including stress urinary and fecal incontinence, and pelvic organ prolapse. Although not often discussed, these conditions are extremely common, with more than 50% of parous women having some degree of a PFD during their lifetime and 11% of women requiring surgery. These disorders severely alter the quality of life of women often leading to isolation and depression. To someone not entirely familiar with internal female pelvic anatomy, it may appear that the vagina is no more important than the rectum or urethra in the development of these disorders. However, the vagina is the primary support structure for the urethra, bladder, uterus, and rectum. The vagina is, in turn, supported by a combination of muscle and connective tissues. A direct insult to the vagina and/or its supportive muscles and tissues compromises the function of other pelvic organs. Thus, it should come as no surprise that excessive stretching and tearing of the vagina during labor and vaginal delivery are predisposing factors for the development of PFDs. It is still unclear, however, which of the structural and mechanical alterations that occur in vaginal tissue during pregnancy predispose women to the development of PFDs. This collaborative project aims to characterize, for the first time, the mechanisms of stretch induced damage and tear propagation in virgin and pregnant rat vaginal tissue. A comprehensive set of ring tests will be conducted to determine the functional role of the tissue?s constituents (collagen, elastin, and smooth muscle cells) on both the active and passive mechanics of the vagina. Planar biaxial tests will be performed to study the tear propagation process. The results of these tests will guide the development of a new constitutive model that will capture the active and passive mechanical response of the vaginal tissue, including stretch-induced damage. The constitutive model will be implemented into a finite element code especially developed to simulate damage and tear propagation of vaginal tissue. For validation, three-dimensional in-vivo experimental data, which are collected by conducting inflation tests that simulate a birth injury within a state-of-the-art 7T micro-MRI, will be utilized.