Canada: A new ultrasound technique can enable the detection of impaired fetal blood flow early in pregnancy, according to a recent study in the Lancet journal eBioMedicine.
The technique uses conventional ultrasound equipment and relies on subtle differences in the pulsation of fetal blood through the arteries at the fetal and placental ends of the umbilical cord. This potentially enables physicians to identify placental abnormalities that impair fetal blood flow and, if necessary, deliver the fetus early. Like current ultrasound techniques, the new technique can also detect the impaired flow of maternal blood through the placenta.
The umbilical artery (UA) Doppler pulsatility index is used clinically for the detection of elevated fetoplacental vascular resistance. However, this metric is confounded by variation in fetal cardiac function and is only moderately predictive of placental pathology. Lindsay S. Cahill, Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada, and colleagues developed a novel ultrasound methodology that measures wave reflections in the UA, thereby isolating a component of the Doppler signal that is specific to the placenta. The study examined whether wave reflections in the UA are predictive of placental vascular pathology.
For the purpose, the researchers performed standard clinical Doppler ultrasound of the UAs in 241 pregnant women. Of these, 40 women met narrowly defined preset criteria for the control group, 36 had maternal vascular malperfusion (MVM) and 16 had fetal vascular malperfusion (FVM). The Doppler waveforms were decomposed into a pair of forward and backward propagating waves using a computational procedure.
Key findings of the study include:
· Compared to controls, wave reflections were significantly elevated in women with either MVM or FVM pathology.
· The umbilical and uterine artery pulsatility indices were only elevated in the MVM group and there were no differences between women with FVM and the controls.
"The principal finding of this work is that wave reflection are elevated in pregnancies with MVM and FVM pathology and, in combination with standard ultrasound parameters, have the potential to improve diagnosis of these pathologies," wrote the authors.
"This is particularly promising for FVM where there is currently no reliable method of detection. The data used in this study were collected using standard clinical ultrasound equipment and automated computational analysis and is therefore easily translated to use at other centers."
Reference:
The study titled, "Wave reflections in the umbilical artery measured by Doppler ultrasound as a novel predictor of placental pathology," is published in the Lancet journal eBioMedicine.
DOI: https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(21)00119-5/fulltext