Obstetrics & Gynecology>>>>>Maternal-Fetal Physiology and Placentation
Question 3#

A 25-year-old P0 presents for routine anatomy ultrasound at 20 weeks’ gestation. The only significant finding at the time of ultrasound is the presence of a single umbilical artery (SUA).

How should you counsel this patient about the finding of a SUA?

a. It is a very common finding and is insignificant
b. Fetal karyotype should be determined, because this finding is associated with an increased risk of aneuploidy
c. Careful anatomic survey should be performed, because it is an indicator of an increased incidence of congenital anomalies of the fetus
d. It is equally common in newborns of diabetic and nondiabetic mothers
e. Even if it is the only abnormality present, SUA is commonly associated with adverse pregnancy outcomes

Correct Answer is C


The finding of a SUA occurs in approximately 1% of pregnancies, and 5% of at least one twin. The incidence of SUA is increased in diabetic mothers. The incidence of major fetal malformations when SUA is identified has been reported to be as high as 18%, and usually involves the cardiac or renal systems; therefore, a careful anatomic survey is indicated. The rate of aneuploidy in the setting of isolated SUA is not increased, so routine karyotype analysis is not needed unless there are other indications to offer this testing. In the absence of other findings, SUA is rarely associated with poor pregnancy outcomes.