A normal umbilical cord consists of two arteries and one vein. These vessels facilitate blood circulation between the pregnant women and the fetus in the womb. When only one artery is present in the umbilical cord, the anomaly is called single umbilical artery. Presence of only one artery can affect the blood supply to the fetus. This is one of the reasons for increased risk of stillbirth, miscarriages, growth retardation and congenital defects.
Single umbilical artery is detected on sonography. The incidence in single pregnancy is around 0.5 to 6 percent whereas the incidence increases 3 to 4 times in twin pregnancies.No one knows precisely the cause of single umbilical artery. But certain factors such as advanced age during pregnancy, maternal diabetes, Caucasian woman etc are supposed to be the risk triggers. Single umbilical artery is considered to be high risk pregnancy and it requires prompt medical management once detected.
Causes Of Single Umbilical Artery
No one exactly knows the reason for development of only one artery in the umbilical cord instead of two. It is believed that one artery simply stops growing during the development of umbilical cord or the umbilical artery may not have split into two during its primary stage.
Single umbilical artery can occur in any pregnant woman, although the incidence is only 1 in 100 pregnancies. High incidence is noted in women of Caucasian origin. These factors may increase the risk:
- Advanced age of pregnant woman.
- Diabetes in pregnant woman.
- Hypertension in mother.
- Chromosomal abnormality including trisomy 13 and trisomy 18.
- Twin pregnancy
- Mother suffering from seizure disorder.
- Velamentous insertion of umbilical cord.
Single Umbilical Artery Complications
Many babies with one umbilical artery are born healthy. But there is an increased risk of complications arising from single umbilical artery. This may include:
- Risk of stillbirths and miscarriages.
- Intrauterine growth retardation (IUGR).
- Low birth weight of the baby.
There is increased risk of congenital fetal defects such as:
- Cleft lip and cleft palate.
- Fused fingers or webbed fingers.
- Spina bifida a defect in the spine of the baby.
- Cystic hydroma.
- Congenital defect in heart such as ventricular septal defect.
- Congenital defect of lung and kidney. Often the symptoms of defect in kidney remain silent till the baby grows.
Treatment For Single Umbilical Artery
A single umbilical artery is usually seen during the routine ultrasound examination performed at the time of pregnancy. Once a single umbilical artery is detected it is considered to be medical emergency. Treatment is aimed to save the fetus and manage complications if any.
Fetus with single umbilical cord artery is at high risk of suffering from stillbirth and miscarriage hence the pregnant women needs to be closely monitored from time to time. After the birth the baby is evaluated regularly for heart and kidney anomalies. It has been observed that one third of children have chromosomal defects such as trisomy 13 and trisomy 18.