Abnormality of ductus venosus blood flow 2011-01-16T03:50:45Z UMLS:C4023632 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. The typical abnormal finding in abnormal ductus venosus flow is a reversed a-wave. HP:0010947 A first-trimester prenatal ultrasound finding of abnormal blood flow in the ductus venosus. Abnormal fetal cardiovascular physiology