In which views is a VSD most readily detected prenatally?

• A. Four-chamber view with color Doppler and short-axis view near inlet/outlet regions
• B. Only three-vessel view
• C. Ductus venosus Doppler
• D. Apical two-chamber view

Answer: (A)

Detecting a ventricular septal defect before birth hinges on planes that best show the interventricular septum and any abnormal flow. The four-chamber view offers a direct look at both ventricles and the septum, allowing visualization of a defect and comparison of ventricular size. Adding color Doppler highlights shunting across the septum as a color jet, increasing sensitivity, even for small defects. Complementing with a short-axis view near the inlet and outlet regions lets you see the septum in cross-section and localize defects that may lie toward the membranous, inlet, or muscular portions, which might be missed in the four-chamber view due to angle or position. Other views have limitations for this purpose: the three-vessel view focuses on great vessel alignment rather than septal integrity; ductus venosus Doppler assesses venous return and fetal hemodynamics rather than structural defects; the apical two-chamber view shows mainly one ventricle and portions of the septum and can miss defects not in that plane. Therefore, combining a four-chamber view with color Doppler and a short-axis view near the inlet/outlet regions provides the best approach to prenatal VSD detection.