Clinical meaning
The umbilical cord is the lifeline connecting the developing fetus to the placenta throughout pregnancy. It contains two umbilical arteries that carry deoxygenated blood and metabolic waste from the fetus to the placenta, and one umbilical vein that carries oxygenated, nutrient-rich blood from the placenta to the fetus. The cord is surrounded and protected by Wharton jelly, a mucoid connective tissue composed primarily of mucopolysaccharides that provides cushioning and prevents compression of the blood vessels. The average cord length is approximately 50 to 60 centimeters, and the average diameter is 1 to 2 centimeters. The cord is covered by a single layer of amnion epithelium continuous with the amniotic membrane. At birth, the umbilical cord is clamped and cut, severing the fetal-placental circulation. The current evidence supports delayed cord clamping (DCC), defined as clamping the cord at least 30 to 60 seconds after birth (and up to 3 minutes in some guidelines), to allow continued blood transfer from the placenta to the newborn. Delayed cord clamping provides the newborn with an additional 80 to 100 mL of blood, increasing iron stores by 30 to 50 mg/kg and reducing the risk of iron deficiency anemia through the first year of life. In preterm infants, DCC reduces the risk of intraventricular hemorrhage and necrotizing enterocolitis and decreases the need for blood transfusions. After clamping and cutting, the cord stump undergoes a process of dry gangrene (mummification). The Wharton jelly desiccates and the cord stump shrinks, darkens from yellowish-green to brown to black, and eventually separates from the skin through a process of leukocyte-mediated enzymatic digestion at the junction between the cord stump and the periumbilical skin. Separation typically occurs between 7 and 21 days of life, with an average of 10 to 14 days. The base of the cord stump, where it meets the abdominal skin, is a portal of entry for bacteria because the thrombosed umbilical vessels communicate with the systemic circulation. The umbilical vein connects to the portal venous system and thus to the liver, while the umbilical arteries connect to the internal iliac arteries. This vascular communication means that infection at the cord stump (omphalitis) can rapidly progress to systemic sepsis, portal vein thrombosis, liver abscess, or necrotizing fasciitis. Omphalitis is a serious neonatal infection with an incidence of approximately 0.7% in developed countries but up to 8% in developing regions. It is caused most commonly by Staphylococcus aureus, Group A Streptococcus, and gram-negative organisms including Escherichia coli and Klebsiella. The clinical presentation includes periumbilical erythema extending beyond the cord base, induration, warmth, purulent or foul-smelling discharge, and periumbilical edema. Systemic signs include fever, lethargy, poor feeding, tachycardia, and irritability. Omphalitis requires urgent medical evaluation and parenteral antibiotic therapy because of the risk of rapid progression to sepsis. Current evidence-based cord care recommendations have evolved significantly. The World Health Organization and major pediatric organizations now recommend dry cord care (also called natural cord care) for healthy term newborns in developed countries: keep the cord stump clean and dry, fold the diaper below the cord stump to prevent urine contamination, expose the stump to air, and avoid applying any antiseptic agents, alcohol, or other substances. Research has demonstrated that dry cord care results in faster cord separation without increasing infection rates compared to antiseptic application. However, in settings with high neonatal mortality and poor hygiene conditions, chlorhexidine 4% application to the cord stump reduces omphalitis and neonatal mortality.