EP09.43: Carotic‐subclavian artery index in the fetal aortic arch between 19 and 22 weeks of gestation

The carotid-subclavian artery index (CSAi) is used to further classify coarction of the aorta (CoA) postnatally. We calculated this ratio in the fetus with normal branching pattern of the aortic arch and its variants in a low-risk population between 19 and 22 weeks of gestation. This prospective cohort study included 262 low-risk singleton pregnancies. We investigated the aortic arch in a sagittal view according to predefined landmarks. Its branching pattern was categorised in classical branching or variants by two operators who were blinded to each other. The CSAi was measured by each operator. Classification of the aortic arch branching was achieved in 260/262 (99.2%) cases. 192 cases (73.4%) showed a classical pattern. Both operators agreed on 55 brachiobicephalic trunks (BBCT), 11 aberrant left vertebral arteries, one aortic arch with five branching vessels and in one case there was disagreement on the type of the variant. Additional, two fetuses showed an aberrant right subclavian artery (0.8%). The CSAi was calculated for the classical branching (1.51, SD +/- 0.46) and the BBCT (0.72,SD +/-0.12) and showed a significant difference, p = 0.002 (see figure 1). In 26% we could identify variants of the aortic arch in a low-risk population. Furthermore, there was a significant difference in the CSAi between classical branching and BBCT. This should be considered in the setting of suspected CoA. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.