What does the three-vessel view assess?

• A. Relative size and orientation of the main pulmonary artery, ascending aorta, and superior vena cava
• B. Growth of fetal brain
• C. Umbilical vein patency
• D. Diaphragm movement

Answer: (A)

The three-vessel view is used to visualize the three great vessels in one cross-section and to assess their size and how they lie relative to each other. This quick look screens for outflow tract and conotruncal abnormalities. In a normal fetus, the main pulmonary artery, ascending aorta, and superior vena cava appear in a compact arrangement with proportional calibers; the vessels’ positions follow a typical pattern. If the vessels show abnormal size relationships or an unusual alignment—such as a parallel, abnormal arrangement of the great arteries—it raises concern for conditions like transposition of the great arteries or other conotruncal lesions. The other options relate to brain growth, umbilical vein patency, or diaphragm movement, which are not assessed by this view.