This view is obviously a key one when looking for a haemodynamically significant PDA, see the functional section for greater discussion of PDA assessment. However ductal patency should be investigated in every echo.
Use a high sagittal view to demonstrate the proximal pulmonary trunk and distal aortic arch. A duct, if patent, will be visible joining the two.
Ductal View Normal:
The duct is often visible on 2D echo:
If shunting left-to-right (systemic to pulmonary) the PDA will be even more clearly visible as red flow towards the probe:
Smaller PDAs may be obviously tortuous:
However a key step is to look for a PDA which is shunting right to left (pulmonary-to-systemic). These ducts appear blue on the screen, and can be very hard to distinguish from the branch pulmonary arteries. However look carefully - a duct shunting right-to-left after the first hour or two of life is ALWAYS pathological, and indicates either persistent pulmonary hypertension of the newborn (PPHN) or structural heart disease.