Umbilical Cord

The Umbilical Cord

Anatomy

• Origin : It develops from the connecting stalk.
• Length: At term, it measures about 50 cm.
• Diameter: 2 cm.

Structure:

 It consists of mesodermal connective tissue called Wharton's jelly, covered by amnion.

It contains:

• One umbilical vein carries oxygenated blood from the placenta to the foetus
• Two umbilical arteries carry deoxygenated blood from the foetus to the placenta,
• Remnants of the yolk sac and allantois.
• Most of the cord consists of a loose mesenchyme with intercellular ground substance (Wharton's jelly).

Insertion:

• The cord is inserted in the foetal surface of the placenta near the center "eccentric insertion" (70%)
• Or at the center "central insertion" (30%).

Abnormalities of the Umbilical Cord

(A) Abnormal cord insertion:

• Marginal insertion :  in the placenta  ( battledore insertion).
• Velamentous insertion: in the membranes and vessels connect the cord to the edge of the placenta.
• Vasa praevia: If these vessels pass at the region of the internal os , the condition is called " Vasa praevia".
• Vasa praevia can occur also when the vessels connecting a succenturiate lobe with the main placenta pass at the region of the internal os

 (B) Abnormal cord length:

• Short cord which may lead to :
• i-Intrapartum haemorrhage due to premature separation of the placenta,
• ii-Delayed descent of the foetus druing labour,
• iii-Inversion of the uterus.
• Long cord which may lead to:
• i-Cord presentation and cord prolapse,
• ii-Coiling of the cord around the neck,
• iii-True knots of the cord.

(C) Knots of the cord:

1.True knot:

• when the foetus passes through a loop of the cord.
• If pulled tight, foetal asphyxia may result.

2. False knot:

• localized collection of Wharton’s jelly containing a loop of umbilical vessels.
• A long umbilical cord may more easily become twisted, or even form a knot

(D) Torsion of the cord:

• may occur particularly in the portion near the foetus where the Wharton's jelly is less abundant.

(E) Haematoma :

• Due to rupture of one of the umbilical vessels.

(F) Single umbilical artery :

• may be associated with other foetal congenital anomalies