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

盆底疾病(PFD)包括许多医疗条件，包括压力性尿失禁和大便失禁，以及盆腔器官脱垂。虽然不常被讨论，但这些情况是非常常见的，超过50%的临产妇女在一生中有不同程度的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。对于一些不完全熟悉女性盆腔内部解剖的人来说，在这些疾病的发展过程中，阴道似乎并不比直肠或尿路更重要。然而，阴道是支撑尿路、膀胱、子宫和直肠的主要结构。反过来，阴道由肌肉和结缔组织共同支撑。对阴道和/或其支撑性肌肉和组织的直接侮辱会损害其他盆腔器官的功能。因此，分娩和阴道分娩过程中阴道过度伸展和撕裂是产后功能障碍的诱因，这一点也就不足为奇了。然而，目前尚不清楚怀孕期间发生在阴道组织中的结构和机械变化中的哪一种会使女性更容易发生产后功能障碍。这一合作项目的目的是首次表征拉伸导致的损伤和撕裂在处女和怀孕大鼠阴道组织中传播的机制。将进行一套全面的环测试，以确定组织中的S成分(胶原蛋白、弹性蛋白和平滑肌细胞)对阴道主动和被动力学的功能作用。将进行平面双轴试验来研究撕裂扩展过程。这些测试的结果将指导开发一种新的本构模型，该模型将捕捉阴道组织的主动和被动机械反应，包括拉伸诱导的损伤。本构模型将被实施到专门为模拟阴道组织的损伤和撕裂扩展而开发的有限元程序中。为了验证，将利用三维体内实验数据，这些数据是通过在最先进的7T微型磁共振成像中进行模拟出生损伤的充气测试而收集的。

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.