What is the Umbilical Cord?
The umbilical cord is a helical, tubular blood conduit that connects the fetus to the placenta, containing two umbilical arteries and one umbilical vein embedded in Wharton's jelly, serving as the critical lifeline for fetal nutrition, oxygenation, and waste removal throughout pregnancy. 1, 2
Anatomical Structure
The umbilical cord achieves its final anatomical form by the 12th week of gestation and consists of the following key components: 2
Blood vessels: Two umbilical arteries (carrying deoxygenated blood from fetus to placenta) and one umbilical vein (carrying oxygenated, nutrient-rich blood from placenta to fetus) 3, 2
Wharton's jelly: A gelatinous connective tissue that surrounds and protects the blood vessels, providing cushioning against compression, twisting, and shearing forces 3, 2
Protective coiling: The cord exhibits a helical (spiral) configuration that provides additional structural protection against mechanical stress during fetal movement and labor 3
Functional Role
The umbilical cord serves as the anatomical bridge between the fetal cardiovascular system and the placenta, enabling: 3
Gas exchange: Oxygen delivery to the fetus and carbon dioxide removal 2
Nutrient transport: Transfer of essential nutrients from maternal circulation to support fetal growth and development 1, 2
Waste removal: Elimination of fetal metabolic waste products 2
Fetal mobility: Unlike the placenta (which is anchored to the uterine wall), the cord's structure allows the fetus to move freely within the amniotic fluid 3
Clinical Significance After Birth
After delivery, the umbilical cord becomes a devitalized structure that requires proper care: 4
Portal for infection: The cord provides direct vascular access to the newborn's bloodstream, making it a common entry point for invasive pathogenic bacteria, particularly Staphylococcus aureus, Group A and B Streptococci, and Gram-negative organisms like E. coli and Klebsiella 4, 5
Risk of omphalitis: Bacterial colonization can lead to umbilical cord infection (omphalitis) with potentially life-threatening complications including sepsis, with case-fatality rates up to 13% in untreated cases 6, 5
Contamination sources: The maternal birth canal and nonsterile hands of delivery attendants represent the primary sources of bacterial contamination 5
Common Abnormalities
Umbilical cord abnormalities are uncommon but clinically significant: 3, 7
Structural variations: Excessively long or short cords, single umbilical artery, velamentous insertion, strictures, and cysts 3, 7
Coiling abnormalities: Hypocoiling (insufficient spiral pattern) or hypercoiling, which may be associated with adverse fetal outcomes 8, 3
Vascular complications: Umbilical cord prolapse (a life-threatening emergency requiring immediate delivery), thrombosis, hematomas, and rarely tumors 3, 9