Single umbilical artery: What you need to know.
Diagnosis/definition: SUA is the result of agenesis or atrophy of one of the umbilical arteries, resulting in a “2-vessel cord”. An SUA can usually be detected on cross-section of the umbilical cord using 2-D imaging; it can also be detected using color-flow Doppler to examine the umbilical arteries in the pelvis.
Epidemiology/Incidence: SUA is seen in up to 1% of all singleton pregnancies, and in up to 4.6% of twin pregnancies. The rate of associated fetal structural anomalies when an SUA is detected has been reported to range from 13% to 56%.
- Evaluation includes a detailed anatomic survey by an experienced provider and assessment of risk factors for aneuploidy, including maternal age, results of other screening or diagnostic tests, and family history.
- If the SUA is associated with other ultrasound findings or aneuploidy risk markers, an increased risk of aneuploidy occurs of 9% (range 0-26%), and counseling regarding invasive diagnostic testing is indicated .
- If, after thorough evaluation, the SUA is felt to be isolated, no additional prenatal testing is indicated. If isolated, fetal echocardiography is felt to offer no added benefit.
- The association of isolated SUA and fetal growth restriction is controversial. At most, a follow-up growth scan in the 3rd trimester, at 30-32 weeks, might provide useful information and reassurance
Last Reaffirmed: Feb 1, 2013