Here are some nice ultrasound and Color Doppler video clips of a 33 week fetus with intra-abdominal umbilical vein varix.
Another Doppler ultrasound video clip:
BL= fetal urinary bladder. VAR= intra-abdominal umbilical vein varix.
Note the close relation of the varix to the urinary bladder. On grey scale ultrasound, the varix may be mistaken for the fetal urinary bladder or a diverticulum from the bladder. (See ultrasound images below):
Spectral Doppler ultrasound trace shows typical venous flow in the varix, albeit turbulent. (See ultrasound picture below).
The turbulent flow within the varix is also seen in the Doppler video clips above.