Blood flow and the degree of shunting through the ductus venosus in the human fetus

Assessment of ductus venosus flow during the first and early second trimesters: what can we expect?

“…Apart from the delivery of welloxygenated blood from the umbilical vein directly to the fetal heart, the ductus venosus plays a key role in the distribution of blood to the fetal liver, which is dependent on gestational age. The average fraction shunted through the ductus venosus decreases from about 30% at 18 weeks to about 18% at 31 weeks 13 . Most importantly, experimental obstruction of the ovine ductus venosus leads to doubling of blood flow to the liver tissues, rapid growth of the liver and significantly increased cell proliferation rates in other tissues such as the myocardium and skeletal muscles, most likely due to the stimulation of growth factors 14 .…”

Spatial velocity profile changes along the cord in normal human fetuses: can these affect Doppler measurements of venous umbilical blood flow?

“…Whether this high data variability reflects a physiological variability or is mainly due to methodological errors has still to be ascertained. In fact, perfect parabolic profiles have been assumed to exist 10 -13 throughout the cord vein or IWMV has been used 14,15 to estimate the mean spatial velocity in the UV.…”

Congenital absence of ductus venosus: an umbilical catheter with an abnormal path

“…DV allows only 20 to 30% of UV blood to bypass the portal circulation and pass directly into the proximal IVC. 13 Therefore, extrahepatic drainage results in the loss of the resistance to placental blood flow that normally is provided by DV and hepatic sinusoids. Jaeggi et al 7 showed that in such cases, the combined cardiac output prenatally is approximately 78% greater than in fetuses with normal anatomy.…”