01
1. The 5 Standard Axial Transverse Planes
Beginning in the upper abdomen and moving cephalad toward the fetal neck, the sonographer must capture five sequential transverse views:
Upper Abdomen (Visceral Situs): Stomach on the left, descending aorta left-posterior, inferior vena cava right-anterior.
Four-Chamber View (4CV): Apex pointing left (~45° ± 20°), two symmetrical atria and ventricles, foramen ovale flap in left atrium, intact interventricular septum, tricuspid valve more apical than mitral valve.
Left Ventricular Outflow Tract (LVOT): Aorta arising from morphological left ventricle with septo-aortic continuity.
Right Ventricular Outflow Tract (RVOT): Pulmonary artery arising from right ventricle and crossing anterior and perpendicular to the ascending aorta.
Three-Vessel and Trachea View (3VT): Pulmonary trunk, ascending aorta, and superior vena cava aligned in descending size order, forming a 'V-shape' to the left of the trachea.
02
2. Color Doppler Optimization in Fetal Echo
Color Doppler must be calibrated with a high pulse repetition frequency (PRF 4000–6000 Hz) to assess unidirectional laminar flow through outflow tracts and confirm absence of regurgitation or shunting.
Confirm concordant flow direction across the aortic arch and ductus arteriosus in the 3VT view.
Reverse flow in the aortic arch indicates critical aortic stenosis, hypoplastic left heart syndrome, or coarctation of the aorta.
Reverse flow in the ductus arteriosus indicates ductal-dependent pulmonary circulation (e.g., critical pulmonary stenosis or atresia).