Triphasic Umbilical Artery Waveform: Association With Severe Fetal Growth Restriction, Fetal Demise, And Extreme Velamentous Cord Insertion

Extreme Doppler abnormalities of the umbilical artery such as absent or reversed end diastolic velocity are associated with adverse perinatal outcomes. We present a case of a triphasic umbilical artery waveform identified at 24 weeks. The fetus was severely growth restricted with an estimated fetal weight of 314 g. A week later, fetal demise occurred. Placental pathology revealed a placental weight of 83 g, an extensive maternal floor infarction, and an extreme velamentous cord insertion 7 cm from the edge of the placental disc, with vessels entering at opposite poles of the placental disc and a single anastomotic bridging vessel on the chorionic plate connecting these two vascular poles. A triphasic umbilical artery waveform may be associated with a premorbid state and severe placental vascular abnormality. We hypothesize that the third and positive component in late diastole is present due to forward flow across the communicating bridging vessel into the contralateral entering vessel.