Doppler Ultrasound of the Fetal Descending Aorta: An Objective Tool to Assess Placental Blood Flow Resistance in Pregnancies With Discordant Umbilical Arteries

Abstract

Objectives-To determine the relationship between blood flow in the fetal descending aorta and discordant umbilical arteries (UAs).Methods-Pulsed wave Doppler of both UAs and the descending aorta was performed at 4-weekly intervals between 14 and 40 weeks of gestation in 209 pregnant women. In datasets with discordant UAs, a linear mixed effects model was used to determine the categorical relationship between the UA pulsatility index (PI) (high, low and average) and the descending aorta PI.Results-Of the 209 cases, 81 had a discordance of greater than 25% in UA PI during one of their visits. There were no differences in birth outcomes between the groups with concordant and discordant UA PIs. In the cases with discordant UA PIs, the descending aorta PI was most strongly associated with both the average UA PI (P = .008), and with the UA with the lower PI (P = .008).Conclusions-The relationship between blood flow in the descending aorta and UAs is consistent with the law for combining resistances in parallel. Measurements of the descending aorta PI, particularly in a scenario with discordant UAs, may inform the stability of the feto-placental circulation where discordant UA PIs are found.

Maternal Oxygen Inhalation Affects the Fetal Hemodynamic in Low-Risk with Uncomplicated Late Pregnancy

“…For measurement of descending aorta (DAo) blood ow: Identify the descending aorta with color ow mapping under the mid-sagittal plane of the fetal abdomen, the sample volume was placed on the level the adjacent diaphragm of the descending aorta, maintain the insonation between ultrasound beam line and the blood ow direction below 45 degree. The doppler index of the ductus venosus in our study included pulsatility index (PI) and resistance index (RI) [20].…”