During pregnancy, the umbilical cord is vital because it carries nutrients and oxygen from the placenta to the developing fetus. Three vessels are usually present in the umbilical cord: two arteries and one vein. The growth and general health of the infant depend on these vessels. Knowing the umbilical cord’s normal structure can help parents distinguish between normal and potentially problematic development.
However, a baby’s umbilical cord may occasionally have just one artery rather than the typical two. This is referred to as a single umbilical artery (SUA) condition. Although it may sound worrisome, a large number of babies with SUA are born healthy and have no serious health problems. However, since SUA can occasionally be linked to other illnesses or developmental issues, it’s critical to keep an eye out for any potential complications.
This article will address the implications of having only one artery as well as describe what a normal umbilical cord should look like. For expectant parents navigating their pregnancy journey, knowing these aspects can offer clarity and reassurance.
Structure and functions
The umbilical cord is a long and very strong organ that is connected by one end to the umbilical hole of the fetus, and with the other with the placenta. The length of the umbilical cord is from 50 to 70 centimeters and even more, it is it that allows the baby to move normally in the uterus, make coups. A shorter umbilical cord complicates the course of pregnancy and is dangerous in the birth process, since its tension at the time of birth of the baby can cause premature rupture and detachment of a large area of the placenta. The thickness of the umbilical cord is about 2 centimeters, it is strong and withstands significant loads, in its structure, resembling durable rubber.
Normally, the umbilical cord has 3 vessels. They are located inside the cable. Umbilical arteries – two. They go from the inner iliac vessels. Two umbilical arteries perform a transport function – they carry the baby’s blood saturated with carbon dioxide and metabolic products to the placenta. The placenta helps to bring out the substances that have become unnecessary into the blood of the mother, so that later they leave her body in the traditional way – with urine, then. The umbilical vein in the structure of the umbilical cord is one. Initially, in the early stages of the development of the fetus, there are also two of them, but one then is expected. The task of the umbilical vein is to carry blood to the baby, enriched with oxygen, vitamins, minerals.
Normal blood flow through the umbilical cord vessels is balanced, meaning that carbon dioxide and metabolic products are eliminated from the blood as it leaves the arteries and is equal to the amount of enriched blood entering the vein. The blood flow through them is close to 35 milliliters per minute at 20 weeks of pregnancy. The blood flow increases with the length of pregnancy, reaching a rate of 230–240 ml per minute on the day of the anticipated birth.
Research methods
Since the umbilical cord’s detailed structure cannot be studied until the second trimester of pregnancy, examination of the cord’s structure is typically not done during the first trimester of pregnancy. The umbilical cord itself may theoretically be seen starting in the seventh week of pregnancy; more accurately, its presence can be established, its attachment site can be identified, and signs of pulsation can be observed in it (typically, this rhythm perfectly matches the baby’s heartbeat).
Later, other important details can be determined on ultrasound – the length of the umbilical cord, the shape of attachment to the placenta, possible entanglement in the neck area. To obtain data on the number of vessels and the speed of blood flow through them, they do the so-called ultrasound with Doppler (USDG). Even if the umbilical cord entanglement could not be established by a regular ultrasound, Doppler will definitely detect it by certain blood flow disturbances. The ultrasound Doppler will establish the exact number of vessels in the umbilical cord, the vascular resistance index and other important mathematical parameters. If there are deviations in the structure of the umbilical cord: it is short – less than 30 centimeters, long – more than a meter, attached not to the central part of the placenta, it has fewer vessels, the woman will be recommended to undergo additional examination.
Reasons for deviations
The most common deviation is a single artery in the umbilical cord. This does not mean that there is only one vessel. It is just that only one of the two arteries is present. Thus, the diagnosis of "a single artery in the umbilical cord" implies that there are still two vessels – a vein and one artery. Blood enriched with nutrients moves to the baby through a vein, and blood contaminated with metabolic products leaves the child"s body through an artery. In principle, one artery copes with the task, but experiences significant overloads. The cause of the abnormal structure of the umbilical cord is often the mother"s diabetes, as well as the presence of chronic diseases of the kidneys, heart, liver. Other unfavorable factors can also affect the laying of the umbilical cord structures – bad habits, infectious diseases, venereal diseases, flu or acute respiratory viral infections in the early stages of pregnancy, as well as causes of unclear etymology, which cannot be determined.
This anomaly has no symptoms, does not affect the course of pregnancy, and in 95% of cases allows a woman to quite normally carry her baby to the due date and give birth to a child. In the singular, the artery can be initially blocked, or it can remain the only one as a result of aplasia of the second artery already during the course of bearing the baby. A single artery can be caused by a genetic predisposition (the baby"s mother or father developed such a pathology during pregnancy), and in some cases, the presence of a single artery can indicate chromosomal abnormalities in the fetus or congenital malformations of the respiratory system, intestines, heart or kidneys. That is why, when one artery is detected instead of the two required by the norm, doctors examine the baby more closely for possible defects and deviations in development and formation – they conduct an expert ultrasound, recommend invasive diagnostics or a non-invasive prenatal DNA test, which is able to determine the baby"s DNA and possible chromosomal pathologies from the fetal blood cells in the mother"s bloodstream.
Women with multiple pregnancies, severe early toxicosis, placental pathologies, and obesity are at risk of developing single umbilical artery syndrome. It will never be advised for the woman to end the pregnancy if it turns out that there is only one artery in the umbilical cord. There are no medical grounds for doing so. The pregnant woman will be observed in normal mode if further studies reveal that the child is healthy. Nevertheless, in the later stages, a KTG scan and an ultrasound with a doppler will be required to evaluate the fetus’s condition.
An emergency cesarean section will be performed if anomalies in a single artery (zero diastolic blood flow, retrograde blood flow) are found in order to prevent the baby from dying from a shortage of oxygen and nutrients.
| Number of Vessels | Meaning |
| Normal Umbilical Cord | Typically has 3 vessels: 2 arteries and 1 vein. |
| Single Artery | Indicates a potential issue; it may be associated with congenital abnormalities or developmental concerns, but can occur in otherwise healthy babies. |
It is crucial to comprehend the umbilical cord’s vessel count when evaluating a baby’s health prior to birth. Three vessels are usually present in the umbilical cord: two arteries and one vein. This configuration guarantees effective transfer of nutrients and oxygen from the mother to the infant while eliminating waste. Single umbilical artery (SUA) is a condition where there is only one artery and one vein in the cord.
Even though having just one artery is not unusual and usually doesn’t present any serious risks, it can occasionally be linked to other medical disorders or developmental problems. It is essential to conduct routine ultrasounds and monitoring to make sure the baby’s growth and development are proceeding as planned. Further testing might be suggested by medical professionals to look for any potential issues.
Babies born with a single umbilical artery are generally healthy. For a smooth and healthy pregnancy, it is imperative to remain informed and adhere to your healthcare provider’s advice. Parents can feel more ready and assured when their baby is born if they are aware of these aspects of umbilical cord health.
Two arteries and one vein are normally present in the umbilical cord, which helps the baby by removing waste and transporting nutrients and oxygen from the placenta. While the presence of a single artery may be suggestive of possible problems, it frequently does not portend major issues. Monitoring the baby’s health during pregnancy is made easier by having an understanding of the typical structure and what changes might entail.
