The most important Fetal veins are, Umbelical vein, ductus venusus.
The main blood flow of Umbelical vein_relative sixty-five percent _is toward to portal vein and 35% direct to dactus venusus that contains well oxygenated blood.This DV blood is direct to IVC with liver bypass then
enter to RA،fossa ovals and LA and LV and AORTA and shifted to head and neck and upper limbs. Concept of ductus venusus circulation and its Doppler pattern is very important to understand of fetal heart physiology.
Venus anomalies of fetus have some sign in ante natal sono/echo such as:
Persistent left svc
Dilated coronary sinus
Thoracic Venus collector