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{{Short description|Vein running from the placenta to the fetus}}
{{Infobox Vein
| Name = Umbilical
| Latin = vena umbilicalis
| Image = Gray502.png
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| Caption2 = Human embryo. [[Human brain|Brain]] and [[Human heart|heart]] represented from right side. [[Digestive tube]] and [[yolk sac]] in median section. (Umbilical vein labeled at bottom left.)
| DrainsTo = [[Inferior vena cava]]
| Artery = [[
}}
The '''umbilical vein''' is a [[vein]] present during [[fetal development]] that carries [[oxygenated blood]] from the [[placenta]] into the growing [[fetus]]. The umbilical vein provides convenient access to the central circulation of a neonate for restoration of blood volume and for administration of glucose and drugs.<ref name=":0" />
The blood pressure inside the umbilical vein is approximately 20 [[mmHg]].<ref>Wang, Y. Vascular biology of the placenta. in Colloquium Series on Integrated Systems Physiology: from Molecule to Function. 2010. Morgan & Claypool Life Sciences.</ref>
==Fetal circulation==
The unpaired umbilical vein carries oxygen and nutrient rich blood derived from fetal-maternal blood exchange at the [[chorionic villi]]. More than two-thirds of fetal hepatic circulation is via the main [[portal vein]], while the remainder is shunted from the left portal vein via the [[ductus venosus]] to the [[inferior vena cava]], eventually being delivered to the fetal [[right atrium]].
==Closure==
Closure of the umbilical vein usually occurs after the [[umbilical arteries]] have closed. This prolongs the communication between the placenta and fetal heart, allowing for a sort of [[autotransfusion]] of remaining blood from the placenta to the fetus.
Within a week of birth, the neonate's umbilical vein is
==Recanalization==
Under extreme [[blood pressure|pressure]], the round ligament may reopen to allow the passage of blood. Such recanalization may be evident in patients with [[cirrhosis]] and [[portal hypertension]]. Patients with cirrhosis experience rapid growth of [[scar|scar tissue]] in and around the liver, often functionally obstructing nearby vessels. [[Vessel occlusion]] increases [[vascular resistance]] and therefore leads to hypertension. In portal hypertension, the vessels surrounding the [[liver]] are subjected to abnormally high blood pressure—so high, in fact, that the force of the blood pressing against the round ligament is sufficient to recanalize the structure. This leads to a condition called [[
==Catheterization==
A newborn baby has a patent umbilical vein for at least a week after birth. This umbilical vein may be catheterised for ready intravenous access. It may be used as a site for regular transfusion in cases of [[erythroblastosis]] or [[hemolytic disease]]. It also provides a route for measuring central venous pressure.<ref name=":0">{{Cite book|url=https://books.google.com/books
==Additional images==
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