Prenatal care uses ultrasound, a non-invasive procedure that uses high-frequency sound waves to create images of structures inside the body. This imaging allows healthcare providers to observe the fetus and its surrounding environment. The umbilical cord is a central component of this environment, facilitating the transport of substances between the pregnant person and the developing baby.
Visibility of the Umbilical Cord
The umbilical cord is routinely visible during prenatal ultrasound examinations. Its clarity can be influenced by several factors, including gestational age, fetal position, and the amount of amniotic fluid.
Different types of ultrasound technology also impact visibility. While 2D ultrasounds provide cross-sectional images, 3D and 4D ultrasounds offer more detailed views, enhancing cord visualization. Sonographers are trained to locate and assess the umbilical cord as a standard part of a prenatal scan.
What the Umbilical Cord Looks Like on Ultrasound
On ultrasound, the umbilical cord typically appears as a coiled, rope-like structure. This appearance is due to its composition, which includes Wharton’s jelly surrounding the blood vessels. The cord’s natural coiling, where arteries spiral around the vein, can also be observed.
In cross-section, the umbilical cord usually reveals three distinct circular structures: two umbilical arteries and one umbilical vein. The arteries carry deoxygenated blood and waste products away from the fetus to the placenta. The larger vein transports oxygenated blood and nutrients from the placenta to the fetus.
Why Doctors Examine the Umbilical Cord
Doctors examine the umbilical cord during ultrasound scans for several medical reasons. They confirm the presence of the typical three vessels (two arteries and one vein), which indicates normal development.
Assessing blood flow through the cord using Doppler ultrasound is another aspect of the examination. This technique measures blood movement between the placenta and baby, indicating adequate oxygen and nutrient supply. Healthy blood flow patterns indicate placental function and fetal well-being.
Healthcare providers also check the cord’s insertion points into the placenta and the baby’s abdomen. They confirm these attachment sites are properly formed and positioned. Any variations are noted, as they can be associated with other developmental considerations.
Common Umbilical Cord Conditions Seen on Ultrasound
Ultrasound can detect various umbilical cord conditions or variations. One finding is a single umbilical artery (SUA), meaning the cord contains only two vessels (one artery and one vein) instead of the usual three. This occurs in approximately 1% of singleton pregnancies. While often an isolated finding, it may prompt a more detailed ultrasound to check for other associations.
A nuchal cord describes the umbilical cord wrapped around the baby’s neck. This is common, present in about 6% to 37% of deliveries, and usually does not lead to complications. Wharton’s jelly typically protects the vessels from compression.
Umbilical cord cysts or masses can also be identified. These are uncommon (less than 1% of pregnancies), and many found in the first trimester resolve without issue. If detected in the second or third trimester, further evaluation may be recommended to determine their nature and associations.
Velamentous cord insertion is a variation where umbilical vessels separate and travel unprotected by Wharton’s jelly through the membranes before reaching the placenta. This differs from typical insertion directly into the placental mass. Found in about 1% of pregnancies, it can be associated with considerations like increased risk of preterm birth or fetal growth differences.