View source for Umbilical veins

{{Infobox Vein
| Name        = Umbilical vein
| Latin       = vena umbilicalis
| GraySubject = 135
| GrayPage    = 519
| Image       = Gray502.png
| Caption     = Fetal circulation; the umbilical vein is the large, red vessel at the far left.
| Image2       = Gray977.png
| Caption2     = Human embryo about fifteen days old. [[Brain]] and [[heart]] represented from right side. [[Digestive tube]] and [[yolk sac]] in median section. (Umbilical vein labeled at bottom right.)
| DrainsFrom  =
| DrainsTo    =
| Artery      = [[umbilical artery]]
| MeshName    =
| MeshNumber  =
| DorlandsPre = v_05
| DorlandsSuf = 12852143
}}


The '''umbilical vein''' is a [[blood vessel]] present during fetal development that carries [[oxygen]]ated [[blood]] from the [[placenta]] to the growing [[fetus]].

== Circulation ==

Attached to the [[uterine lining]], the placenta is the site of [[gas exchange]] between mother and fetus. The singular umbilical vein carries oxygenated blood from the placenta to the fetus, while two [[umbilical artery|umbilical arteries]] return deoxygenated blood to the placenta. The three vessels coil around one another within the [[Wharton's jelly]] of the [[umbilical cord]] and enter the [[abdomen]] at the [[umbilicus]].

Inside the fetus, the vein courses alongside the [[falciform ligament]] and then to the [[liver]]'s underside. At the [[transverse fissure]], the vein divides into two vessels, one larger than the other. The larger of the two is joined by the [[portal vein]], and together they enter the right lobe of the liver. The smaller vessel, now called the [[ductus venosus]], diverges away from the liver and joins with the [[inferior vena cava]].

==Closure==
Within a week of birth, the infant's umbilical vein is completely obliterated and is replaced by a fibrous cord called the [[Round ligament of liver|round ligament of the liver]] (also called the ''ligamentum teres hepatis'', from the [[Latin]] meaning the same). It extends from the umbilicus to the transverse fissure, where it joins with the [[ligamentum venosum]] to separate the left and right [[lobe]]s of the liver.

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.

== Recanalization ==

Under extreme [[blood pressure|pressure]], the round ligament may reopen to allow the passage of blood. Such recanalization is common in patients with [[cirrhosis]] and [[portal hypertension]]. Patients with cirrhosis experience rapid growth of [[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&mdash;so high, in fact, that the force of the blood pressing against the round ligament is sufficient to recanalize the structure.

==Catheterization==
A newborn baby has a patent umbilical vein for at least a few months. 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]].

==Additional images==
<gallery>
 Image:Gray31.png|Model of human embryo 1.3 mm. long.
 Image:Gray39.png|Scheme of placental circulation.
 Image:Gray458.png|Diagram of the vascular channels in a human embryo of the second week.
 Image:Gray476.png|Human embryo with heart and anterior body-wall removed to show the sinus venosus and its tributaries. 
 Image:Gray989.png|Schematic figure of the bursa omentalis, etc. Human embryo of eight weeks.
 Image:Gray1088.png|Liver with the septum transversum. Human embryo 3 mm. long.
 Image:Gray1115.png|Tail end of human embryo twenty-five to twenty-nine days old.
</gallery>

== References ==
* {{GraySubject|139}} - "Peculiarities in the vascular system of the fetus"

==External links==
* {{EmbryologyTemple|Heart98/heart97a/sld020}}

== See also ==
* [[Human umbilical vein graft]]

{{Veins}}
{{Embryology}}
{{Development of circulatory system}}

[[Category:Embryology]]
[[Category:Veins]]

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[[ja:臍帯静脈]]

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