Umbilical vein
Umbilical vein · SaO2 ~80% PO2 30-35 mmHg
The single vein of the cord, carrying the most oxygenated blood in the fetus (SaO2 ~80%, PO2 ~30-35 mmHg) from the placenta through the umbilicus, along the free edge of the falciform ligament to the inferior surface of the liver, where it joins the left branch of the portal vein.
Traced from the start
- Placenta
- Umbilical vein
Detail
- Saturation
- ~80% (PO2 ~30-35 mmHg), the highest anywhere in the fetus
- Course
- Umbilicus -> free edge of falciform ligament -> porta hepatis; joins the left portal vein and gives off the ductus venosus
- Number
- Single left umbilical vein (the right regresses in the embryonic period); the cord has two arteries and one vein
- Closure
- Constricts later than the arteries, so blood can still drain from placenta to baby during delayed cord clamping; lumen obliterated over 2-3 months
- Adult remnant
- Ligamentum teres hepatis in the free edge of the falciform ligament (hover to see)
When it goes wrong
Umbilical venous catheter in a sick neonate
Passes umbilical vein -> left portal vein -> ductus venosus -> IVC; tip belongs at the IVC-right atrial junction (about T8-T9 on X-ray). A tip lodged in the portal vein or a hepatic branch risks hepatic necrosis, portal vein thrombosis and extravasation
Delayed cord clamping (at least 60 s)
Placental transfusion of up to ~80-100 mL through the still-patent vein: higher haemoglobin and iron stores and less anaemia of prematurity, at the cost of more jaundice needing phototherapy
Practise this structure
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