OC02.07: Fetal left brachiocephalic vein in normal and abnormal conditions

Abstract

Objectives: To describe an extended algorithm CASSEAL for exploring the fetal cardiovascular system at the level of the fetal abdomen and thorax by ultrasound (US) axial views and the features concerning its clinical application. Methods: CASSEAL was applied in a cross-sectional study on 429 singleton and multiple gestations from the second trimester attending our unit for routine US examination or because of a suspected fetal abnormality. Using the common 5 axial views to evaluate de fetal heart (Yagel) as a starting point, we extend the exploration area caudally, adding 3 axial views to assess the hepatic venous circulation and cranially, 2 axial views for the upper mediastinum. This way CASSEAL is based on the acquisition of these 9 different axial views in B mode, from the umbilical vein to the subclavian arteries (Figure 1). The frequencies of visualization for each view and for all 9 views were determined, as was the time for the complete assessment of the 9 views. Interobserver agreement was previously estimated in a sample of 31 gestations (Kappa index, 0.89). Results: Figure 1 shows the 9 axial views that constitute the CASSEAL and illustrates the cardiovascular structures visualized in each view. Views I–III are used to assess the afferent and efferent vessels of the fetal liver and VIII–IX to study the upper mediastinum structures. The frequencies of visualization for each view and the complete set of the 9 views are shown in Table 1. Median exploration time was 5 minutes (IQR, 3–10 minutes). Conclusions: CASSEAL views were feasible and the 9 sonographic axial views were obtained relatively quickly in most cases (>73%). VIII view (Thy-box) presented the lowest frequency of visualization (74.6%). Clinical application of CASSEAL is useful for systematizing the US exploration of fetal cardiovascular structures and, thus, could contribute to the prenatal diagnosis of arterial, venous, and cardiac abnormalities given its wider exploration area.