abnormal ductus venosus morphology duplication of ductus venosus MP:0013879 double ductus venosus duplication of the embryonic connection between the portal vein and inferior vena cava formed by the left umbilical vein that allows oxygenated blood to bypass the developing liver during the time when this connection is normally open; this normally closes during develpment to adulthood duplication of ductus venosus