The pitfalls

Babies are active and fragile, so getting the images takes practice

Even if you transect the path through the ductus vensosus to the cava-atrial junction you still may not see the line on USS through the liver parenchyma, you may just be missing the reflection back of the ultrasound beams. Below is the same line, not seen and seen.

Further to this, the portal sinuses and hepatic veins are thick-walled and their echogenicity can give them a similar appearance to a catheter

Do not get confused with hepatic veins that lead into the cava-atrial junction too.