The umbilical vein is a

vein Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated ...

present during fetal development that carries

oxygenated blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the ci ...

from the

placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mate ...

into the growing

fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...

. 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. The blood pressure inside the umbilical vein is approximately 20

mmHg A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high, and currently defined as exactly pascals. It is denoted mmHg or mm Hg. Although not an ...

.Wang, Y. Vascular biology of the placenta. in Colloquium Series on Integrated Systems Physiology: from Molecule to Function. 2010. Morgan & Claypool Life Sciences.

Fetal circulation

The unpaired umbilical vein carries oxygen and nutrient rich blood derived from fetal-maternal blood exchange at the

chorionic villi Chorionic villi are villi that sprout from the chorion to provide maximal contact area with maternal blood. They are an essential element in pregnancy from a histomorphologic perspective, and are, by definition, a product of conception. Branche ...

. More than two-thirds of fetal hepatic circulation is via the main

portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approx ...

, 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 The umbilical artery is a paired artery (with one for each half of the body) that is found in the abdominal and pelvic regions. In the fetus, it extends into the umbilical cord. Structure Development The umbilical arteries supply deoxygenated ...

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 obliterated and is replaced by a fibrous cord called the

round ligament of the liver The round ligament of the liver (or ligamentum teres, or ligamentum teres hepatis) is a ligament that forms part of the free edge of the falciform ligament of the liver. It connects the liver to the umbilicus. It is the remnant of the left umbi ...

(also called '). It extends from the umbilicus to the transverse fissure, where it joins with the falciform ligament of the liver to separate segment 4 from segments 2 and 3 of the left hepatic lobe.

Recanalization

Under extreme

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country a ...

, the round ligament may reopen to allow the passage of blood. Such recanalization may be evident in patients with

cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue rep ...

and

portal hypertension Portal hypertension is abnormally increased portal venous pressure – blood pressure in the portal vein and its branches, that drain from most of the intestine to the liver. Portal hypertension is defined as a hepatic venous pressure gradient ...

. 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 The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it i ...

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 caput medusae.

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.

Additional images

File:Gray31.png, Model of human embryo, 1.3 mm. long. File:Gray39.png, Scheme of placental circulation. File:Gray458.png, Diagram of the vascular channels in a human embryo of the second week. File:Gray476.png, Human embryo with heart and anterior body-wall removed to show the sinus venosus and its tributaries. File:Gray989.png, Schematic figure of the

lesser sac The lesser sac, also known as the omental bursa, is a part of the peritoneal cavity that is formed by the lesser and greater omentum. Usually found in mammals, it is connected with the greater sac via the omental foramen or ''Foramen of Wins ...

, etc. Human embryo of eight weeks. File:Gray1088.png, Liver with the septum transversum. Human embryo, 3 mm. long. File:Gray1115.png, Tail end of human embryo, twenty-five to twenty-nine days old. File:Umbilical vein.jpg, Umbilical vein File:Slide1MINI.JPG, Human embryo, 38 mm, 8–9 weeks.

References

External links

* {{DEFAULTSORT:Umbilical Vein Embryology of cardiovascular system Veins