Umbilical Cord

30-100 cms REF: Dutta 6′^h ed p. 40

The normal length of umblical cord is around 50cms with usual variation between 30-100 cms

Ans. is d i.e. Umbilical cord

Umbilical cord – A quick revievs.

• Umbilical cord (or Tunis) extends from the fetal umbilicus to the fetal surface of the placenta or chorionic plate.
• It develops from the connecting stalk.°
• In the early fetal life, cord has 2 arteries and 2 veins but later right umbilical vein disappears, leaving only the original left vein (i.e. Left is left)°. Thus at term umbilical cord has 2 arteries and 1 vein.°

Single umbilical artery is present in about 1-2 % of cases.

It may be due to failure of development of one artery or due to its atrophy in later months.

It is more common in twins and in babies born of diabetic mothers or in polyhydramnios.

It is frequently associated with congenital malformation of the fetus. Renal and genital anomalies, trisomy 18 are common.

Umbilical cord: The umbilical cord consist of two arteries and one vein. The arteries carries deoxygenated blood from the fetus to the placenta and the vein carries oxygenated blood from the placenta to the fetus.

The cord at term normally has two arteries and one vein. The right umbilical vein usually disappears early during fetal development, leaving only the original left vein. 

• Diabetes
• Epilepsy 
• Preeclampsia
• Antepartum hemorrhage
• Oligohydramnios or hydramnios AND
• Chromosomal abnormalities 

• Initially, the umbilical veins drain into the sinus venosus but at 5 weeks of development they begin to drain into the hepatic sinusoids.
• The right umbilical vein ultimately disappears and the left umbilical vein later drains directly into the hepatocardiac channel bypassing the hepatic sinusoids through the ductus venosus.
• Remnant of ductus venosus becomes the ligamentum venosum at the termination of the lesser omentum under the left liver.

10^th day after delivery

D. i.e. Right vein 

A i.e. Right umbilical vein disappears; C i.e. Umbilical vein carries oxygenated blood

Oxygenated (80% saturated) blood from placenta is carried in^.umbilical veins, which enters the fetus at umbilicus and run in free nirgin of falciform ligament of liver to reach developing liver. Wheres deoxygenated blood is carried via 2 umblical arteries from fetus to placenta. At 4^th month the right umbilical vein disappears so the umbilical cord contains 2 umblical arteries & left umbilical vein. Left umbilical vein is left and right umbilical vein disappears.

After birth left umbilical vein form ligamentum teres of liver; ductus venosus form ligamentum venosum; umbilical artery forms superior vesicle artery (from proximal portion) and medial umbilical ligament (from distal part);

 vitelline vein forms – “HIPS” i.e. Hepatic vein, Inferior vena cava (inferior portion), Portal vein, Superior mesenteric vein.

B i.e. 4 week

The constituents of the umbilical cord when fully developed are covering epithelium, wharton’s jelly, blood vessels, remnant of the umbilical vesicle (yolk sac) and its vitelline duct, allantois and obliterated extraembryonic coelom Umbilical cord:

• The umbilical cord develops from and contains remnants of the yolk sac and allantois.
• It forms by the fifth week of fetal development, replacing the yolk sac as the source of nutrients for the fetus.
• The length of the umbilical cord is approximately equal to the crown-rump length of the fetus throughout pregnancy.
• The umbilical cord in a full term neonate is usually about 50 centimeters (20 in) long and about 2 centimeters (0.75 in) in diameter.
• The blood flow through the umbilical cord is approximately 35 ml / min at 20 weeks, and 240 ml / min at 40 weeks of gestation.
• Adapted to the weight of the fetus, this corresponds to 115 ml / min / kg at 20 weeks and 64 ml / min / kg at 40 weeks.

Cloacal duct

• It is a small communication between the 2 portions of the hindgut.
• Down growth of the urorectal septum is believed to close this duct by 7 weeks’ gestation.

Umbilical vein carries oxygenated blood to embryo

Ans. is ‘c’ i.e., Urachus