Causes and Risks of a Two-vessel Cord in a Baby

Ideally, an umbilical cord consists of two arteries and one vein. However, in some rare cases, the umbilical cord may have only one artery and one vein. This is known as a two-vessel cord or single umbilical artery (SUA). This is found in 1% of single and 5% of twin pregnancies.

What causes a two-vessel cord?

Doctors and researchers are yet to find out the exact cause of a two-vessel cord. However, broad assumptions relate to the following:

• Multiple pregnancies, that is if you are pregnant with twins, or triplets

• Your age, especially if you are above 40 years of age

• Lifestyle habits such as smoking

• The mother-to-be is diabetic

• Taking medicines like phenytoin during pregnancy

How is SUA diagnosed?

Two vessel cord is usually diagnosed during a prenatal ultrasound. During the second trimester, at around 18 weeks, your doctor will do a colour doppler ultrasound. It is easier to detect a two-vessel cord using a colour doppler ultrasound machine. SUA can be diagnosed using a colour doppler machine as early as 14 weeks.

Risks of single umbilical artery

Earlier, there was a misconception that a single umbilical artery increases the risk of chromosomal abnormalities that causes Down syndrome. However, that is not true.

Nevertheless, the chances of having Trisomy 18, another chromosomal abnormality, known as Edward’s symptom is still doubted in babies born with two-vessel cords. A recent study confirmed that a fetus born with a two-vessel cord and another anomaly like a cleft often has other structural defects. The fetus with isolated SUA usually has no other significant anomalies but is at a higher risk of intrauterine growth retardation.

The risks include:

• Heart problems

• Kidney issues

• Spinal defects

• VATER (vertebral defects, anal atresia, transesophageal fistula with esophageal atresia, and radial dysplasia)

• Trisomy 18 (Edward’s syndrome)

• Small-sized babies

• Infant death

Additionally, the mother may develop high blood pressure in the third trimester.

Conclusion

Two-vessel cord is a rare condition. Many babies are born healthy while some may develop complications. If your doctor diagnoses SUA, they will perform more tests to confirm there are no other anomalies and the baby is growing fine.