Objective To provide an in‐vivo description of early corpus callosum (CC) development. Methods We reviewed 3D US volumes acquired transvaginally (TVUS) through the anterior fontanelle, between 14 to 17 weeks. The following landmarks were recognized: tela‐choroidea (TC), foramina of Moro, early CC and the evolving cavum septi pellucidi. The following measurements were taken: total, anterior and posterior sections, and height of the CC (referenced to the anterior TC border). All measurements were correlated to both the gestational age and the transverse cerebellar diameter (TCD). Results Eighty nine volumes were included in the study (mean 15.1 weeks ± 0.84, TCD range, 13.1‐18.4 mm) with high inter and intra observer correlation of the measurements. We found high correlation between CC length and height, and TCD. The anterior segment of the CC appear earlier than the posterior one, and growth continues bi‐directionally. Initially, the posterior elongation is significantly larger than the anterior one. Association of all CC measurements with TCD remained significant when co‐varying for maternal age and fetal sex. Conclusions imaging the fetal CC is feasible from 14 weeks by TVUS, by following the suggested insonation approach. The early CC develops bi‐directionally, and the posterior elongation is more significant than the anterior one.
Objective The study aims to describe our two‐dimensional (2D) ultrasound approach to visualize the fetal secondary palate and plot its growth curve and to describe and demonstrate its clinical implementation. Methods This is a two parts retrospective study. First, we measured the antero‐posterior length of the bony secondary palate, from the soft to hard palate interface (SHPI) line to the alveolar ridge, blindly by two operators during routine scans of low‐risk fetuses, and plot a longitudinal growth curve. In the second part, we describe four cases of prenatal diagnosis of secondary palate cleft. Results Sixty‐eight fetuses were included: 14 to 15 weeks (n = 20), 21 to 24 weeks (n = 32), and 29 to 35 weeks (n = 16). The bony secondary palate elongates along gestation from a mean of 5.3 mm (+/−0.46 mm) at 14 to 15 weeks to 15.9 mm (+/−1.7 mm) at 29 to 35 weeks. We found high intraobserver and interobserver correlation between measurements. All four cases diagnosed by this approach were confirmed postnatally. Conclusions The SHPI, representing the normally developed secondary bony palate, can be imaged in the fetus by direct 2D ultrasound as early as 14 weeks. A gap within or nonvisualization of the SHPI is highly suggestive for a secondary palate cleft.
Objectives To provide evidence to support the hypothesis that the midline cyst‐like fluid collection that is frequently observed on fetal brain ultrasound (US) imaging during the early second trimester represents a normal transient cavum veli interpositi (CVI). Methods This was a retrospective analysis of 89 three‐dimensional normal fetal brain volumes, acquired by transvaginal US imaging in 87 pregnant women between 14 and 17 gestational weeks. The midsagittal view was studied using multiplanar imaging, and the maximum length of the fluid collection located over (dorsal to) the tela choroidea of the third ventricle was measured. We calculated the correlation of the transverse cerebellar diameter (TCD) and of the maximum length of the fluid collection with gestational age according to last menstrual period. Color Doppler images were analyzed to determine the location of the internal cerebral veins with respect to the location of the fluid collection. Reports of the second‐trimester anatomy scan at 22–24 weeks were also reviewed. Results Interhemispheric fluid collections of various sizes were found in 55% (49/89) of the volumes (mean length, 5 (range, 3.0–7.8) mm). There was a strong correlation between TCD and gestational age (Pearson's correlation, 0.862; P < 0.001). There was no correlation between maximum fluid length and gestational age (Pearson's correlation, –0.442; P = 0.773). Color Doppler images were retrieved in 32 of the 49 fetuses; in 100% of these, the internal cerebral veins coursed within the echogenic roof of the third ventricle. The midline structures were normal at the 22–24‐week scan in all cases. Conclusions In approximately half of normal fetuses, during the evolution of the midline structures of the brain, various degrees of fluid accumulate transiently in the velum interpositum, giving rise to a physiologic CVI. Patients should be reassured that this is a normal phenomenon in the early second trimester that, if an isolated finding, has no influence on fetal brain development. © 2020 International Society of Ultrasound in Obstetrics and Gynecology
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