Can Sevim Tuncer, Golbasi Hakan, Bayraktar Burak, Saglam Ceren, Omeroglu Ibrahim, Torun Raziye, Ucar Ilker, Toka Ilknur Gumus, Ekin Atalay
Department of Perinatology, City Hospital of Izmir, Izmir, Türkiye.
Department of Obstetrics and Gynecology Division of Perinatology, University of Health Sciences Ankara Etlik City Hospital, Ankara, Türkiye.
J Perinat Med. 2024 Dec 2;53(2):213-221. doi: 10.1515/jpm-2024-0393. Print 2025 Feb 25.
To assess the sonographic visualization of the fetal optic chiasm (OC) and optic tracts (OTs), establish mid-trimester reference values, and assess the relationship between OC and OT dimensions and cavum septum pellucidum (CSP) measurements.
This prospective cross-sectional study included 154 morphologically normal fetuses between 19 and 23 weeks of gestation. The diameters of the fetal OC and OTs were measured using two-dimensional transabdominal ultrasound in a transventricular axial section angled approximately 20-40° caudally. CSP length as well as anterior, middle, and posterior widths were measured by placing the cursor on the inner surfaces in the transventricular section. The average CSP width was included in the analysis.
The OC and OTs were successfully visualized in 109 fetuses and included in the analysis. Visualization success in transabdominal axial sections at 19-23 weeks was 70.8 %, with high intraobserver and interobserver reproducibility. Additionally, visualization rates were higher in advanced gestational weeks and in fetuses with breech presentation (p=0.007 and p=0.017, respectively). OC and OT dimensions were positively correlated with CSP length and width, biparietal diameter (BPD), head circumference (HC), and gestational age (p<0.05, for all).
The OC and OTs were successfully visualized transabdominally in axial sections with high intraobserver and interobserver reproducibility. Additionally, OC and OT dimensions were positively correlated with gestational age, as well as with BPD, HC, and CSP measurements.
评估胎儿视交叉（OC）和视束（OT）的超声可视化情况，建立孕中期参考值，并评估OC和OT尺寸与透明隔腔（CSP）测量值之间的关系。
这项前瞻性横断面研究纳入了154例妊娠19至23周、形态正常的胎儿。采用经腹二维超声在经心室轴位切面（尾侧成角约20 - 40°）测量胎儿OC和OT的直径。通过将光标置于经心室切面的内表面来测量CSP的长度以及前、中、后宽度。分析中纳入CSP的平均宽度。
109例胎儿的OC和OT成功可视化并纳入分析。19至23周经腹轴位切面的可视化成功率为70.8%，观察者内和观察者间的可重复性高。此外，孕晚期和臀位胎儿的可视化率更高（分别为p = 0.007和p = 0.017）。OC和OT尺寸与CSP长度和宽度、双顶径（BPD）、头围（HC）以及孕周呈正相关（所有p均<0.05）。
OC和OT在经腹轴位切面上成功实现可视化，观察者内和观察者间的可重复性高。此外，OC和OT尺寸与孕周以及BPD、HC和CSP测量值呈正相关。
