P214: Doppler ultrasound analysis of the human placental vasculature

Abstract

To investigate the functional link between the velocity flow waveforms and the placental vascular resistance resulting from the umbilical arteries and the primary and secondary arterial branches as they enter into the placenta. Doppler ultrasound measurements of the placental FVW from 19 normal pregnancies from 20–40 weeks of gestation were carried. Measurements of PS, ED, S/D, PI, and RI were performed in the artery in the umbilical cord insertion into the placenta, in the first generation of the blood vessels on the chorion plate, and at the half width of the placenta below the insertion (intraplacental vessels). The data were analyzed according to the week of gestation, where a linear trend line was drawn in order to evaluate the general pattern. The results indicated that the normal variation of the flow in the placental vessels correlated well to the umbilical cord flow elsewhere. The flow in the chorionic blood vessels decreased as it entered the intraplacental vessels, both lower than the flow in umbilical cord insertion as expected. The velocities at PS and ED increased towards the end of the pregnancy. The indices PS, ED, S/D, PI, RI in the insertion of the umbilical cord yielded similar patterns along the week of gestation, although higher values, than in the intraplacental blood vessels. The values measured in the chorionic blood vessels were close to those of the intraplacental vessels at 20 week of gestation while later, towards the 40 week of gestational age, the values of the chorionic blood vessels were close to these at cord insertion into the placenta. The blood flow velocity along the placental vascular tree is reduced when moving to smaller blood vessels, due to increase in the resistance of the vessels. The PS and ED were the most sensitive parameters. Changes in the flow in the intraplacental vessels may reflect peripheral damage within the placenta prior to changes in the umbilical arteries.