FREQUENCY AND NATURE OF STRUCTURAL ANOMALIES IN FETUSES WITH SINGLE UMBILICAL ARTERIES

Published studies differ concerning the rate of anomalies occurring in the presence of a single umbilical artery and the significance of the single umbilical artery as an isolated sonographic finding. We assess ed the frequency, nature, and sonographic detection of structural anom alies in fetuses with a single umbilical artery. We identified all cas es in which prenatal sonography diagnosed a single umbilical artery. C ases were excluded if postnatal physical or pathologic examination dem onstrated a three-vessel cord, yielding a study population of 167 case s. For each case, we recorded the gestational age at diagnosis of sing le umbilical artery and the findings of the sonographic fetal anatomic survey. We recorded postnatal clinical and pathologic information whe n available. Gestational age at time of diagnosis ranged from 16.8 to 41.1 weeks (mean, 29.2 +/- 6.5 weeks). Twenty of the 167 fetuses (12%) were twins, and the remainder were singletons. Among 118 cases with p ostnatal information, 37 (31%) had structural abnormalities, often inv olving multiple organs. The most common organ systems involved were th e heart (19 cases) and the gastrointestinal (14 cases) and central ner vous systems (nine cases). Five of the anomalous fetuses had abnormal karyotypes. The sonographic survey was abnormal in 31 of the 37 anomal ous fetuses (84%). Among 85 rases with apparently isolated single umbi lical artery at sonography and known fetal outcome, six (7%) proved to be anomalous at birth. We had two sonographic false-positive results (mild hydronephrosis, suspected skeletal dysplasia). in summary, appro ximately one third of fetuses with single umbilical artery have struct ural anomalies, most often cardiac. Even when the single umbilical art ery is an apparently isolated sonographic finding, the likelihood that the neonate will prove to have structural anomalies is considerable ( 7% in our series).