The umbilical cord is the life-sustaining connection between a developing fetus and the placenta throughout pregnancy. This tube-like structure transfers oxygen and vital nutrients from the mother’s bloodstream to the baby. It also carries waste products away from the fetus back to the placenta for elimination, ensuring healthy fetal development until birth.
Structure and Appearance of the Functional Cord
The mature umbilical cord at term is a thick, rope-like structure that typically measures about 50 to 60 centimeters (20 to 24 inches) in length, with a diameter of roughly 1 to 2 centimeters (less than an inch). Its external surface is smooth, shiny, and often appears whitish-blue or grayish-blue. The cord frequently exhibits a visibly twisted or coiled pattern along its length, which adds tensile strength and helps prevent compression of the internal vessels.
Internally, the cord houses three main blood vessels: two umbilical arteries and one umbilical vein. The arteries, which are thick-walled and smaller in diameter, carry deoxygenated blood and waste away from the fetus to the placenta. The single, thin-walled vein is larger and transports oxygen-rich, nutrient-filled blood toward the baby.
The three vessels are embedded within a protective, gelatinous substance known as Wharton’s jelly. This mucous connective tissue provides insulation and structural support, preventing the vessels from kinking or being squeezed shut. The vessels and the surrounding jelly are encased in a thin outer membrane called the amnion.
The Umbilical Stump Immediately After Birth
After birth, the cord is clamped and cut, leaving a small segment attached to the baby’s abdomen called the umbilical stump. This remaining piece is usually short, measuring approximately 1 to 3 inches in length. A sterile plastic clip is secured near the base of the stump to stop blood flow.
The stump is a thick, moist piece of tissue that may appear yellowish-white, pale yellow, or bluish-white. The cut end may reveal the cross-section of the three vessels embedded in the transparent Wharton’s jelly. Since the stump does not contain nerves, the cutting and subsequent healing process is painless for the newborn.
Visual Changes During Healing
The appearance of the umbilical stump changes as it begins the drying process. Over the next few days, the stump loses its moist, plump texture and starts to shrivel and harden. This drying process is accompanied by a change in color, shifting from its original pale hue to a darker brown, gray, or even black.
The stump will continue to dry and shrink until it detaches completely, a process that usually takes between one and three weeks. A small amount of dark discharge or a few specks of blood may be seen just before or when the stump falls off, similar to a scab coming away. Once the stump separates, the forming navel may look slightly red, moist, or raw.
This spot should heal completely within about two weeks, gradually forming the baby’s permanent belly button. Occasionally, a small, reddish, moist lump of scar tissue called an umbilical granuloma may form at the site, sometimes oozing a clear or yellowish fluid. This is a common and harmless occurrence that a healthcare provider can address.