Normal fetal echo: 3 vessel view:

Basic fetal echo study consists primarily of 1) fetal 4 chamber view of fetal heart 

2) 3 vessels view 

The 3 main vessels are the superior vena cava, aorta and pulmonary artery from right to left. Thus the order of the 3 vessels is:

SAP

Below are color Doppler ultrasound images of normal 3 vessels view in a 3rd trimester fetus. 

A point to note 📝:

I don't always get a perfect 3 vessels view all the time. It's a bit tricky especially with color Doppler for this view. But increasing or adjusting PRF helps during color Doppler of these vessels. 

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3 vessels view: color Doppler fetal heart