To investigate the ultrasound characteristics and clinical significance of different types of left brachiocephalic vein (LBCV) abnormalities in fetuses.

Forty-three cases of LBCV abnormalities diagnosed at Wuhan University People's Hospital from January 2018 to November 2021 were included, and fetal complications, chromosome examination, and clinical follow-up outcomes were retrospectively summarized. The ultrasonographic features and clinical significance of different types of LBCV abnormalities were then analyzed and summarized. In addition, 248 normal fetuses were examined. The inner diameter of the normal LBCV was measured and its correlation with gestational age was analyzed.

The 43 cases of LBCV abnormalities included the following three types: Abnormal course of the LBCV (traveling under the aortic arch in 25 fetuses, penetrating the thymus in 6, and retroesophageal or retrotracheal LBCV in 2); absent LBCV in 7 fetuses; and abnormal diameter of the LBCV (significantly widened inner diameter in 2 fetuses, and smaller inner diameter in 1). Nineteen were detected with other malformations, including right aortic arch, tetralogy of Fallot, transposition of the great arteries, persistent left superior vena cava, and total anomalous pulmonary vein communication. The mean inner diameter of the LBCV in normal fetuses at 18 to 34 weeks ranged from 1.9 mm to 3.98 mm, which showed a positive linear correlation with gestational age. The regression equation was: LBCV inner diameter (mm)=-0.6796+0.1352× gestational age (GA).

The position, course, and morphology of the LBCV can be observed by prenatal ultrasound. The inner diameter of the normal LBCV increases linearly with gestational age. Knowing the ultrasonographic features and clinical significance of different types of LBCV abnormalities can provide information and evidence for clinical consultation.