Occasionally, there is only the one single umbilical artery (SUA) present in the

umbilical cord In placental mammals, the umbilical cord (also called the navel string, birth cord or ''funiculus umbilicalis'') is a conduit between the developing embryo or fetus and the placenta. During prenatal development, the umbilical cord is physiologi ...

. This is sometimes also called a two-vessel umbilical cord, or two-vessel cord. Approximately, this affects between 1 in 100 and 1 in 500 pregnancies, making it the most common umbilical abnormality. Its cause is not known. Most cords have one vein and two arteries. The vein carries oxygenated blood from the placenta to the baby and the arteries carry deoxygenated blood from the baby to the

placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mate ...

. In approximately 1% of pregnancies there are only two vessels —usually a single vein and single artery. In about 75% of those cases, the baby is entirely normal and healthy. One artery can support a pregnancy and does not necessarily indicate problems. For the other 25%, a 2-vessel cord is a sign that the baby has other abnormalities—sometimes life-threatening and sometimes not. Doctors and

midwives A midwife is a health professional who cares for mothers and newborns around childbirth, a specialization known as midwifery. The education and training for a midwife concentrates extensively on the care of women throughout their lifespan; co ...

often suggest parents take the added precaution of having regular growth scans near term to rule out

intrauterine growth restriction Intrauterine growth restriction (IUGR), or fetal growth restriction, refers to poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's ...

, which can happen on occasion and warrant intervention. Yet the majority of growth restricted infants with the abnormality also have other defects. Finally, neonates with the finding may also have a higher occurrence of renal problems, therefore close examination of the infant may be warranted shortly after birth. Among SUA infants, there is a slightly elevated risk for post-natal urinary infections.

Presentation

Associations

SUA does increase the risk of the baby having cardiac, skeletal, intestinal or renal problems. Babies with SUA may have a higher likelihood of having other

congenital abnormalities A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can r ...

, especially of the heart. However, additional testing (high level ultrasound scans) can rule out many of these abnormalities prior to birth and alleviate parental anxiety. It may be associated with Trisomy 18, also known as

Edwards syndrome Edwards syndrome, also known as trisomy 18, is a genetic disorder caused by the presence of a third copy of all or part of chromosome 18. Many parts of the body are affected. Babies are often born small and have heart defects. Other features inc ...

. Intrauterine growth restriction has been found to be associated.

Diagnosis

It can be detected in the first trimester of pregnancy with the use of 2D ultrasound. The sonographer is able to identify a 2 vessel cord in an image with the bladder and color Doppler, which will show only one artery going around one side of the bladder. In a normal fetus, there would be 2 arteries (one on each side of the bladder).

Echocardiogram An echocardiography, echocardiogram, cardiac echo or simply an echo, is an ultrasound of the heart. It is a type of medical imaging of the heart, using standard ultrasound or Doppler ultrasound. Echocardiography has become routinely used in th ...

s of the fetus may be advised to ensure the heart is functioning properly. Genetic counseling may be useful, too, especially when weighing the pros and cons of more invasive procedures such as chorionic villus sampling and

amniocentesis Amniocentesis is a medical procedure used primarily in the prenatal diagnosis of genetic conditions. It has other uses such as in the assessment of infection and fetal lung maturity. Prenatal diagnostic testing, which includes amniocentesis, is n ...

. These invasive procedures are usually performed when there is a suspected chromosomal abnormality or genetic defect and will confirm a diagnosis.

Prognosis

Although the presence of an SUA is a risk factor for additional complications, most fetuses with the condition will not experience other problems, either in utero or after birth. Especially encouraging are cases in which no other soft markers for congenital abnormalities are visible via ultrasound. Given that, the vast majority of expectant mothers do not receive the kind of advanced ultrasound scanning required to confirm SUA in utero.

Epidemiology

It is slightly more common in multiple births, in infants with chromosome anomalies, and in girls than in boys.

References

External links

{{Congenital vascular defects Congenital vascular defects