Abnormal cardiovascular system physiology Persistent patent ductus venosus 2012-07-26T10:10:58Z Persistence of blood flow through the ductus venosus for longer than the normal time after birth. UMLS:C4023072 The ductus venosus is a bypass between the umbilical vein and the inferior vena cava in the fetus. The blood flow through this bypass decreases immediately after birth. Functional closure, which is followed by anatomic closure, is virtually complete within a few weeks of birth. HP:0012021 Fetal anomaly