has part has part has_part characteristic of has modifier abnormal ductus venosus morphology absent ductus venosus MP:0013880 absence of ductus venosus absence 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 development to adulthood abnormal absent ductus venosus