Silva M E T, Oliveira D A, Roza T H, Brandão S, Parente M P L, Mascarenhas T, Natal Jorge R M
INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
Department of Gynecology and Obstetrics, Centro Hospitalar de São João-EPE, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal.
J Biomech. 2015 Jun 25;48(9):1600-5. doi: 10.1016/j.jbiomech.2015.02.032. Epub 2015 Feb 26.
Pelvic floor injuries during vaginal delivery are considered a significant risk factor to develop pelvic floor dysfunction. The molding of the fetus head during vaginal delivery facilitates the labor progress, since it adjusts to the birth canal geometry. In this work, a finite element model was used to represent the effects induced by the passage of the fetus head on the pelvic floor. The numerical model used for this simulation included the pelvic floor muscles attached to the bones, and a fetus body. The model of the fetus head included the skin and soft tissues, the skull with sutures and fontanelles, and the brain. The fetus head movements during birth in vertex position were simulated: descent, internal rotation and extension. Two models of the fetus head were compared: a rigid and a deformable one, with the inclusion of the cranial sutures. The influence of the fetus head molding on the pelvic floor muscles was analyzed by evaluating their reaction forces, stretch, and stress and strain fields. Additionally, anatomical indices for the molding of the fetal skull were obtained and compared with clinical data. The passage of the deformable fetus head through the birth canal leads to a reduction of 17.3% on the reaction forces on the pelvic floor muscles when compared to the ones of a rigid head. Furthermore, the fetus head molding implies inferior resistance to rotation resulting in a reduction of 1.86% in muscle stretching. Quantitative evaluation of the fetus head molding showed good agreement with clinical experiments.
阴道分娩期间的盆底损伤被认为是发生盆底功能障碍的一个重要危险因素。阴道分娩过程中胎儿头部的塑形有助于产程进展，因为它能适应产道的几何形状。在这项研究中，使用了一个有限元模型来表示胎儿头部通过对盆底产生的影响。用于该模拟的数值模型包括附着在骨骼上的盆底肌肉和一个胎儿身体。胎儿头部模型包括皮肤和软组织、带有缝线和囟门的颅骨以及大脑。模拟了胎儿头部在顶点位分娩时的运动：下降、内旋转和伸展。比较了两种胎儿头部模型：一种是刚性的，另一种是可变形的，并纳入了颅缝。通过评估盆底肌肉的反作用力、拉伸以及应力和应变场，分析了胎儿头部塑形对盆底肌肉的影响。此外，还获得了胎儿颅骨塑形的解剖学指标并与临床数据进行了比较。与刚性头部相比，可变形胎儿头部通过产道会使盆底肌肉的反作用力降低17.3%。此外，胎儿头部塑形意味着旋转阻力较小，导致肌肉拉伸减少1.86%。对胎儿头部塑形的定量评估与临床实验结果吻合良好。
