Single Umbilical Artery
Single umbilical artery (SUA) is the most common malformation of the umbilical cord. On its own, SUA does not necessarily pose a risk to you or your child as an umbilical cord with just one artery is sufficient to support a pregnancy to term. However, SUA does increase your child’s risk for certain birth defects.
What is Single Umbilical Artery?
Normally, when the umbilical cord develops, it forms three vessels: two arteries and one vein. However, in some cases, just one artery develops. Precisely why this occurs is not entirely known. It is suspected, though, that one artery may simply stop growing as it develops or perhaps that the primordial umbilical artery does not divide properly.
How Common is SUA?
This malformation of the umbilical cord has been found to affect between 0.5% and 7% of pregnancies and 1 in 100 live births. Caucasian women are twice as likely to experience this complication compared to Japanese and Black women. Additionally, women having a multiple pregnancy are three to four times as likely to develop SUA. Other factors that may increase your risk:
- Advanced maternal age (over 40)
- Having 3 or more previous children
- Female fetal sex
Although SUA can affect either artery, the left artery tends to be absent slightly more often than the right.
How Will I Know if I have SUA?
Although some babies may not be diagnosed until birth, most times, the problem can be diagnosed through an ultrasound scan. During an ultrasound, an SUA diagnosis will be made if the technician notices that one artery is abnormally large and that only two vessels are visible instead of three.
Alternatively, a colour doppler ultrasound may also be done. In this instance, the colour doppler will be used to visualize the arteries. If you have single umbilical artery, then only one vessel will be seen on the screen on either side of your baby’s bladder.