Ductus venosus
Ductus venosus
Also known as: ligamentum venosum, Arantius duct
The ductus venosus is a fetal vein inside the liver. It carries part of the oxygen-rich umbilical venous blood straight to the IVC, bypassing the liver sinusoids. After birth it closes and becomes the ligamentum venosum.
Overview
The ductus venosus joins the umbilical part of the left branch of the portal vein to the IVC, near where the hepatic veins enter. Its narrow entrance (isthmus) works like a nozzle, speeding the blood up so that it forms a fast, well-oxygenated stream. This stream travels preferentially across the foramen ovale to the left heart.
The ductus venosus carries about a quarter of the umbilical venous blood in late pregnancy. More passes through it in mid-pregnancy and when the fetus is hypoxic. It closes within days to weeks after birth. The fibrous remnant, the ligamentum venosum, lies in the fissure between the caudate and left lobes of the liver.
Function
- In the fetus, sends oxygen-rich umbilical blood past the liver to the heart.
Clinical significance
Ductus venosus Doppler
In first-trimester screening, an absent or reversed a-wave on Doppler of the ductus venosus is linked to chromosomal abnormalities and heart defects. In fetal growth restriction, the ductus venosus Doppler helps decide when to deliver the baby.
Umbilical venous catheter
In newborns, an umbilical venous catheter is passed through the umbilical vein and ductus venosus into the IVC. If the ductus venosus stays open abnormally, portal blood bypasses the liver, which can cause high ammonia levels.
Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.