Agnathia-otocephaly complex (AOC) is a rare and complex craniofacial malformation characterized by mandibular hypoplasia or agnathia, auricular fusion (synotia), and microstomia with oroglossal hypoplasia or aglossia. It can occur alone or in combination with forebrain anomalies and cardiac malformations and has an extremely poor prognosis. Here, we report a case of AOC diagnosed by systemic fetal screening at a gestational age of 25 +4 weeks. Ultrasound revealed that the S-curve formed by the normal lower jaw and lower lip had disappeared, the lower jaw and mandible were invisible, the mouth was extremely small, and the oral fissure was "pinhole-shaped". There was a cone-shaped perioral bulge.Both ears were located in the front side of the neck, and the right foot was inverted. Excessive amniotic fluid was observed. The absence of a mandible was confirmed on X-ray examination after induced abortion.Specimen observation showed that the ear positions were extremely low, and both earlobes were connected in the front side of the neck. It was particularly challenging to identify the development of the mandible and locate auricles during prenatal ultrasound diagnosis, and the prenatal diagnosis of AOC was confirmed by combining two-dimensional and three-dimensional ultrasound in our current case.

Retroesophageal or retrotracheal left brachiocephalic vein (LBCV) is a rare anatomic variant that is often associated with congenital heart disease. It is rarely reported in fetal life, and an isolated fetal retroesophageal LBCV has a good prognosis: it is typically asymptomatic, although respiratory symptoms or swallowing disorders occasionally occur. A variant was observed on fetal echocardiography at 22 +6 weeks of gestation. The 3-vessel view revealed a transverse section of a vessel to the left of the pulmonary artery.Tracing upwards along its long axis showed that the left subclavian vein joined the left internal jugular vein to form the LBCV, and tracing downwards revealed that the vessel traveled to the right and lower side, where it merged into the superior vena cava via the azygos vein behind the aortic arch. The variant was identified as retrotracheal LBCV. Three-dimensional (3D) reconstruction of fetal great vessels was performed using temporal spatial correlation imaging. The left internal jugular vein and the left subclavian vein converged into the LBCV, then bypassed behind the trachea and converged into the superior vena cava via the azygous vein. As a 3D technique, spatio-temporal image correlation (STIC) can visualize the abnormal courses of LBCV, thus improving the diagnostic accuracy. This article presents the 2-dimensional (2D) ultrasound, color Doppler, and STIC findings of an isolated retrotracheal LBCV, which may inform the sonographic diagnosis of such variants.