Three-dimensional magnetic resonance imaging of fetal head molding and brain shape changes during the second stage of labor

Abstract

To demonstrate and describe fetal head molding and brain shape changes during delivery, we used three-dimensional (3D) magnetic resonance imaging (MRI) and 3D finite element mesh reconstructions to compare the fetal head between prelabor and the second stage of labor. A total of 27 pregnant women were examined with 3D MRI sequences before going into labor using a 1 Tesla open field MRI. Seven of these patients subsequently had another set of 3D MRI sequences during the second stage of labor. Volumes of 2D images were transformed into finite element 3D reconstructions. Polygonal meshes for each part of the fetal body were used to study fetal head molding and brain shape changes. Varying degrees of fetal head molding were present in the infants of all seven patients studied during the second phase of labor compared with the images acquired before birth. The cranial deformation, however, was no longer observed after birth in five out of the seven newborns, whose post-natal cranial parameters were identical to those measured before delivery. The changing shape of the fetal brain following the molding process and constraints on the brain tissue were observed in all the fetuses. Of the three fetuses presenting the greatest molding of the skull bones and brain shape deformation, two were delivered by cesarean-section (one after a forceps failure and one for engagement default), while the fetus presenting with the greatest skull molding and brain shape deformation was born physiologically. This study demonstrates the value of 3D MRI study with 3D finite element mesh reconstruction during the second stage of labor to reveal how the fetal brain is impacted by the molding of the cranial bones. Fetal head molding was systematically observed when the fetal head was engaged between the superior pelvic strait and the middle brim.

Difficult birth is the main contributor to birth‐related fracture and accidents to other neonatal fractures

“…The recent publication by Ami et al gives an indication of the strong forces acting on the head during birth; maybe clinically silent skull fractures are much more common after birth than reflected in the data presented here. As the head in most infants is the largest part of the body to pass the birth canal, and as it undergoes an almost extreme moulding during this passage, one would expect these forces to cause skull fractures to a larger extent than revealed in the present study.…”

“…Skull fractures are rare in modern obstetrics (0.001‐0.01%), although they may be underestimated, as an incidence of 2.9% has also been reported . Considering the fact that the head in the majority of infants is the largest part of the body to pass the birth canal, and that it undergoes an almost extreme moulding during this passage, it is conceivable that some skull fractures may remain undetected. Greenstick skull fractures are stated to be the most common, followed by depressed and linear type .…”

The extraperitoneal French AmbUlatory cesarean section technique leads to improved pain scores and a faster maternal autonomy compared with the intraperitoneal Misgav Ladach technique: A prospective randomized controlled trial

“…Twenty years after their invention, intraperitoneal CS techniques such as MLCS remain widely used [ 4 ]. Today, approximately 1 in 5 births worldwide is performed by CS due to various factors influencing medical decision-making [ 5 ] and their intuitive protective effect in cases of cephalopelvic dystocia [ 6 ]. However, CS techniques remain pathogenic and traumatic compared with vaginal delivery.…”

A Machine Learning Enhanced Mechanistic Simulation Framework for Functional Deficit Prediction in TBI

“…Those need to be chosen carefully depending on the level of detail (e.g., homogenized brain vs. independent white and gray matter) but also loading conditions. For instance, blast loading conditions would typically require equations of state to adequately capture the volumetric response under shock waves and the viscous-relaxation processes can a priori be ignored for very short time-scales (Moore et al, 2009 ), while slow loading scenarios, such as in the second stage of labor, when the head of the foetus is being compressed in the vaginal canal, would ideally require viscoelastic laws to capture the fetal head molding of the infant head (Ami et al, 2019 ). Any intermediate situation, such as the ones considered here, would need to balance the need for time-dependent models against the timescales involved, along with other features more or less relevant depending on the leading deformation mechanisms: whether viscoelastic models are required, whether tissue damage and/or fracture should be accounted for, whether tissue anisotropy is relevant, etc.…”