Cephalometric assessment of human fetal head specimens.

BACKGROUND: Past investigations of prenatal craniofacial growth have largely relied on histological sections. Few studies have taken measurements on three-dimensional representations (3D reconstruction, 3D CT, postmortem) or varying depth levels (ultrasound), and we know of no craniofacial growth studies done on cleared-and-stained specimens of whole fetal heads. MATERIALS AND METHODS: This study comprised 14 human fetal head specimens cleared and stained with alizarin red and alcian blue. They had been stored in glycerol and represented weeks 8-12 of gestation, with crown-rump lengths ranging from 23-145 mm. These specimens were cephalometrically analyzed in norma frontalis and norma lateralis, which notably included the opportunity for side-to-side comparison. RESULTS: As the cranial membrane bones progressively approached each other, the orbits, maxilla, and mandible gradually grew wider. Likewise, the sagittal dimensions of the maxilla and mandible increased continuously and synchronically. We noted side-to-side differences ranging from 2-5 mm. Another notable finding concerned the inclination of the maxilla relative to the cranial base, which increased more on the right than on the left side. CONCLUSION: This is the first investigation presenting side-to-side comparative measurements of human fetal head specimens. Such measurements are essential in the quest toward validating the findings of other imaging techniques such as CT or MRI and-most importantly-intrauterine sonography.

Two- and three-dimensional sonographic assessment of the fetal face. 1. A systematic analysis of the normal face.

OBJECTIVES: To detail fetal facial examination in utero using ultrasound, to distinguish between requirements for routine screening and those for precise analysis of fetal facial features, and to assess the use of three-dimensional (3D) ultrasound imaging in fetal facial examination. METHODS: This was a retrospective study, based on the examination of approximately 10,500 fetuses. The usual age at screening ultrasound examination was 22 +/- 1 gestational weeks. RESULTS: The sonographic anatomy of the normal fetal face was depicted, and the relevance of the three reference scanning planes, sagittal, coronal and axial, was specified. CONCLUSIONS: At routine screening using two-dimensional sonography, at least two selected views must be imaged: the mid-sagittal plane (search for facial dysmorphology) and the anterior 'nose-mouth' coronal plane (search for disruption in lip continuity or deformation of the narinal bend). Precise analysis of fetal facial anomalies requires visualization and thorough step-by-step analysis in the three planes. The difference between routine screening and precise facial features' analysis has been greatly decreased since 3D and 4D sonography have become readily available. Using this modality, after surface analysis of the fetal face, the three reference planes are simultaneously imaged, using the multiplanar modality, and detailed. 3D/4D ultrasound imaging allows easier, more rapid screening and more precise evaluation of the different facial features.