Transvaginal three-dimensional ultrasound assessment of embryonic genital tubercle at 8–10+6 weeks of gestation

Abstract

Abstract Objectives To assess embryonic genital tubercle using transvaginal three-dimensional (3D) ultrasound at 8–10+6 weeks of gestation. Methods One-hundred and two transvaginal 3D ultrasound scans were performed for first-trimester dating at 8–10+6 weeks of gestation. The genital tubercle angle (GTA) and genital tubercle length (GTL) were measured with a mid-sagittal view of the embryo using the 3D ultrasound multiplanar mode. Intra- and inter-observer agreements regarding GTA and GTL were also assessed with Bland–Altman plots and intra- and inter-correlation coefficients. Results There were no significant differences in GTA between male and female embryos at 8, 9, 10 weeks, or 8–10+6 weeks of gestation, respectively. There were also no significant differences in GTL between male and female embryos at 8, 9, 10 weeks, or 8–10+6 weeks of gestation, respectively. However, GTL increased linearly with advancing gestation (r=0.8276, p<0.00001). Mean GTL (SD) values at 8, 9, and 10 weeks were 0.833 mm (0.274), 1.623 mm (0.262), and 2.152 mm (0.420), respectively (p<0.001). Intra- and inter-reproducibilities of GTA and GTL were excellent. The intra- and inter-correlation coefficients of GTA and GTL were 0.964 and 0.995, and 0.996 and 0.9933, respectively. Conclusions The genital tubercle could be identified using transvaginal 3D ultrasound at 8–10+6 weeks of gestation. However, sex differentiation could not be performed at this age. The genital tubercle linearly developed with advancing gestation during the mid-first trimester of pregnancy.