Single Umbilical Artery

Ashish Jain, Kaushaki Shankar

Case Scenario

A 23-year-old primigravida underwent a level-2 antenatal ultrasonography (USG) screening at 20 weeks of gestation. The USG revealed the presence of an isolated single umbilical artery (SUA) in the umbilical cord. No other fetal anomaly was identified on detailed evaluation.


SUA affects 0.2% to 1.2% of all live births, with a high incidence in twins and abortuses. The second and third trimester ultrasound scans should routinely include umbilical cord evaluation. Once SUA is diagnosed, the fetus should be screened for other structural anomalies, including genitourinary, cardiovascular, and musculoskeletal defects. A detailed repeat scan, fetal echocardiography, and invasive tests are warranted to detect chromosomal abnormalities such as trisomies 13 and 18 only if an isolated abnormality is detected. The SUA may elevate maternal serum PAPP-A and AFP levels, hence the adjustments should be made for SUA before the results are interpreted. Even in the absence of other congenital anomalies, because of the high incidence of IUGR, preterm labor, and adverse fetal outcomes, isolated SUA pregnancies should be kept under frequent surveillance.

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