Inflation and rupture of vaginal tissue

Abstract

Around 80% of women experience vaginal tears during labour when the diameter of the vagina must increase to allow the passage of a full-term baby. Current techniques for evaluating vaginal tears are qualitative and often lead to an incorrect diagnosis and inadequate treatment, severely compromising the quality of life of women. In order to characterize the failure properties of the vaginal tissue, whole vaginal tracts from rats ( n = 18) were subjected to free-extension inflation tests until rupture using a custom-built experimental set-up. The resulting deformations were measured using the digital image correlation technique. Overall, the strain and changes in curvature in the hoop direction were significantly larger relative to the axial direction. At a failure pressure of 110 ± 23 kPa (mean ± s.d.), the hoop and axial stresses were computed to be 970 ± 340 kPa and 490 ± 170 kPa, respectively. Moreover, at such pressure, the hoop and axial strains were found to be 12.8 ± 4.4 % and 6.4 ± 3.7 % , respectively. Rupture of the vaginal specimens always occurred in the hoop direction by tearing along the axial direction. This knowledge about the rupture properties of the vaginal tissue will be crucial for the development of clinical approaches for preventing and mitigating vaginal tearing and the associated short- and long-term traumatic conditions.

Data‐driven variational multiscale reduced order modeling of vaginal tissue inflation

“…The geometry, boundary conditions, and material parameters used to construct the FE model that describes the deformations of rat vaginal specimens subjected to luminal pressure were selected to approximate experimental data 31,32 . During the experiments, the vaginal tissue was mounted onto dispensing needles and inflated via a pressure pump with phosphate buffered saline.…”

“…Thus, we constructed our model geometry based on the shape and average dimensions of the vaginal tissue specimens with the applied pre-load, as well as the outer diameters of the dispensing needles. 31 Construction of the model and subsequent finite simulations for the vaginal tissue were carried out within Abaqus/Standard (Abaqus 2020, Dassault Systèmes Americas Corp., Waltham, MA). All simulations were performed on a 24-core Intel ® Xeon ® Gold 6248R CPU @ 3.00GHz with 191 GB of usable RAM.…”

“…In this work, we propose reduced order modeling as an efficient and accurate means of approximating the vaginal tissue deformation. To this end, we first use our knowledge of the ex vivo micro-structural and mechanical behavior of the rat vaginal tissue from experimental data 31,32 to develop a FOM using the FE method. We then investigate the feasibility of ROM techniques to approximate the deformations of the rat vagina subjected to various levels of luminal pressure and having different collagen fiber organization.…”

Bioengineering in women's health: part I

“…Contradictory to the prevailing hypothesis from the literature, the authors observe the superficial perineal structures inhibit perineal body anterior-posterior displacement, thus impacting simulations of vaginal delivery by inferiorly displacing and stretching the perineal body. Gordon et al McGuire et al [6] characterize the failure properties of rat vaginal tissue and found that rupture occurs in the circumferential direction by tearing along the axial direction. The authors suggest these new findings will be important for designing clinical strategies to minimize vaginal tearing.…”

“…The contributions by McGuire et al [6] and Clark et al [7] leverage extension -inflation biomechanical tests to determine the material failure properties and the role of smooth muscle cells in rodent vaginal tissue, respectively. McGuire et al [6] characterize the failure properties of rat vaginal tissue and found that rupture occurs in the circumferential direction by tearing along the axial direction. The authors suggest these new findings will be important for designing clinical strategies to minimize vaginal tearing.…”