left umbilical vein

n.
  1. A vein that returns blood from the placenta to the fetus, traversing the umbilical cord to pass into the liver, where it is joined by the portal vein.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.