The single umbilical artery in a high-risk patient population: what should be offered?

To determine whether fetal echocardiography is warranted in cases of single umbilical artery in a population at risk for aneuploidy. All cases of fetal single umbilical artery identified over a 2‐year period were reviewed for other sonographically detected abnormalities, fetal echocardiographic results, and karyotype. Sixty‐five cases of single umbilical artery were diagnosed on the basis of initial sonograms. Five were subsequently shown to have 3‐vessel cords (8% false‐positive diagnosis; incidence, 1.2%). Excluding 3 from twin gestations, 57 cases formed the study population. Thirty‐one fetuses (54%) were initially thought to have isolated single umbilical arteries, and 26 (46%) had nonisolated single umbilical arteries. Fetal echocardiography was performed in 29 cases (51%), 24 (83%) with normal findings and 5 (17%) with abnormal findings. Four (50%) of 8 nonisolated single umbilical arteries had abnormal echocardiographic findings versus 1 (5%) of 21 apparently isolated single umbilical arteries (P < .05; odds ratio, 20). Karyotypes in 36 cases (63%) showed 25 (69%) euploid and 11 (31%) aneuploid fetuses. An apparently isolated single umbilical artery was never associated with an abnormal karyotype. Eleven (50%) of 22 fetuses with nonisolated single umbilical arteries had aneuploidy (P < .005). The side of the missing umbilical artery did not correlate with other sonographically detected abnormalities, abnormal fetal echocardiographic findings, or aneuploidy. The rate of cardiac malformations seen with apparently isolated single umbilical arteries is significant, and fetal echocardiography should be performed.