SINGLE UMBILICAL ARTERY - DOES IT MATTER WHICH ARTERY IS MISSING

OBJECTIVE: Our purpose was to determine whether the presence of congen ital anomalies in fetuses with a single umbilical artery is related to the side of the missing artery. STUDY DESIGN: During an 18-month pros pective study, the side of the missing artery was identified in all pr egnancies with a single umbilical artery (n = 77). Targeted sonograms and perinatal follow-up were obtained. RESULTS: The left umbilical art ery was absent in 56 of 77 (73%) fetuses, compared with 21 of 77 (27%) for the right artery, p < 0.0001. Congenital anomalies occurred in 20 of 77 (26%) fetuses, with 16 of 56 (29%) in those with absence of the left artery and 4 of 21 (19%) in those with absence of the right arte ry, p = 0.561. Complex congenital anomalies occurred in 9 of 20 (45%) fetuses. All complex anomalies had absence of the left artery, p = 0.1 03. Cytogenetic abnormalities were noted in 6 fetuses, all with absenc e of the left artery, p = 0.181. In fetuses with a single umbilical ar tery as an isolated finding, small-for-gestational-age fetuses occurre d in 4 of 50 (8%) pregnancies. CONCLUSION: In fetuses with a single um bilical artery the left artery is more commonly absent than the right artery. In our series cytogenetic and complex fetal anomalies occurred exclusively in fetuses with absence of the left artery. In contrast t o previous reports, the incidence of small-for-gestational-age fetuses does not appear to be increased in cases of an isolated single umbili cal artery.