has part has part has_part characteristic of has modifier abnormal vascular regression patent ductus venosus MP:0004004 failure 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) to close in adults MPheno.ontology abnormal ductus venosus morphology abnormal closure incomplete ductus venosus