State Key Laboratory of Virtual Reality Technology and System, Beihang University, Beijing, China.
Med Eng Phys. 2011 Jun;33(5):620-5. doi: 10.1016/j.medengphy.2010.12.018. Epub 2011 Jan 20.
Fetal head molding is important for adapting the fetal head to the birth canal during vaginal delivery; however, excessive deformation of fetal head may lead to severe complications. Although labor force is one of the major factors which cause deformation of the fetal head, its effect on fetal head molding has not been quantitatively investigated yet. We examined this effect by using a finite element modeling approach. Firstly, a geometric model was created by scanning a polyethylene replica of fetal skull model with a white light three-dimensional scanner. Secondly, a nonlinear finite element model was proposed based on the geometric model. Next, the simulation results of the proposed model were verified against the experimental data reported in other literatures and they showed good agreement with the experimental observations. After this validation, the proposed model was used to simulate the fetal skull deformations under different labor forces. Simulation results illustrated that the fetal skull diameters and modified molding index (MMI) increased when the labor force was increased. Parietal bone around bregma and frontal bone around coronal suture undertook more stress, and parietal and frontal bones around coronal suture undertook more spatial and rotational displacement under larger labor force. The suboccipito-bregmatic diameter (SOBD) was more sensitive to the changes of labor force than other fetal skull diameters. The simulation results revealed the quantitative relationship between the labor force and fetal skull molding during delivery. In the future, if the degree of fetal skull molding is directly related to that of the head injury, the relationship investigated in this study may be used to predict the head injury by measuring the labor force during delivery.
胎儿头部塑形对于阴道分娩时胎儿头部适应产道非常重要；然而，胎儿头部过度变形可能导致严重并发症。尽管劳动力是导致胎儿头部变形的主要因素之一，但它对胎儿头部塑形的影响尚未得到定量研究。我们使用有限元建模方法研究了这种影响。首先，使用白光三维扫描仪扫描聚乙烯胎儿颅骨模型的复制品来创建几何模型。其次，基于几何模型提出了一个非线性有限元模型。接下来，将提出的模型的模拟结果与其他文献中报道的实验数据进行了验证，结果与实验观察吻合良好。在验证之后，使用该模型模拟了不同劳动力下的胎儿颅骨变形。模拟结果表明，当劳动力增加时，胎儿颅骨直径和修正塑形指数（MMI）增加。额骨和顶骨在矢状缝周围承受更大的压力，并且在更大的劳动力下，顶骨和额骨在冠状缝周围承受更大的空间和旋转位移。枕额径（SOBD）比其他胎儿颅骨直径对劳动力变化更敏感。模拟结果揭示了分娩过程中劳动力与胎儿头部塑形之间的定量关系。将来，如果胎儿头部塑形程度与头部损伤程度直接相关，那么本研究中调查的关系可以通过测量分娩时的劳动力来预测头部损伤。
