What malformations are common in single umbilical artery?

The development of the fetus is of great concern to women throughout the pregnancy, for fear that the child will have some frightening problems. Among them, fetal malformation is the most common and has the greatest impact on the development of the fetus. Single umbilical artery development problems are prone to occur, which has a devastating effect on the fetus. Let's take a look at what malformations of single umbilical artery are more common? I hope everyone can understand it.

A single umbilical artery is generally not a problem. However, the probability of fetal malformation is very high. It is recommended to check chromosomes again if there is no obvious abnormality in the ultrasound examination. The incidence of malformation, premature birth, stillbirth, etc. in pregnancies with single umbilical artery is very high, and close monitoring is recommended.

The fetal blood circulation is very amazing, and substances are exchanged entirely through the umbilical blood vessels. The umbilical artery originates from the iliac arteries on both sides, but it flows with venous blood. After entering the placenta, it is converted into arterial blood and transported to the inferior vena cava through the umbilical vein, gradually mixing with the venous blood and supplying nutrients and oxygen to the whole body.

Under normal circumstances, the fetus's umbilical cord blood vessels are two umbilical arteries and one umbilical vein. Some fetuses have only one umbilical artery and one vein. This phenomenon is called single umbilical artery, a type of vascular variation. The incidence rate is 0.46% in single live births, 0.8% in multiple pregnancies, and 6.1-11.3% in newborns with chromosomal abnormalities. Its occurrence mechanism has not yet been fully elucidated and its clinical significance is still under study.

Studies have shown that the probability of fetuses with a single umbilical artery having other congenital developmental abnormalities is about 10 times higher than that of fetuses with a double umbilical cord, so it can be used as a predictor of fetal malformation. However, the presence of a single umbilical artery alone cannot be used as a criterion for chromosome testing. Pregnant women only need to undergo an ultrasound fetal anomaly screening before 28 weeks of pregnancy. If other concurrent malformations are found, a chromosome test must be performed.

In most cases, a fetus with a single umbilical artery without other malformations is exactly the same as a fetus with double umbilical arteries, but in a few cases there may be an impact. Previous studies have shown that single umbilical artery is associated with intrauterine growth retardation, so pregnancies with single umbilical artery are generally considered "high-risk" and require close obstetric evaluation and follow-up observation. From an anatomical point of view, a single umbilical artery will lead to a decrease in placental return volume. Compensatory mechanisms will generally make up for this defect, but it will still lead to a decrease in the fetus's tolerance to certain special situations. The probability of hypoxia in a single umbilical artery is slightly higher than that in a double umbilical artery.