New technique and conventional ultrasounds improve detection of fetal circulation pathology


Providers can use a new ultrasound technique to more accurately detect problems with blood flow in the placenta, which could lead to improved diagnosis of fetal pathologies.

Placental problems occur in more than half of all cases of fetal growth restriction (FGR) or stillbirth each year. FGR affects up to 10 percent of pregnancies each year, and it is present in about 20 percent of stillbirths. Therefore, it is essential to be able to effectively detect blood circulation problems.

Currently, providers use Doppler ultrasound to assess part of the health of the fetus by measuring the pulsality of umbilical artery blood velocity waveforms. But, several factors, including fetal heart rate, can make an accurate examination and determination difficult.

In a study published in eBiomedicine, a team of researchers from the Hospital for Sick Children in Toronto tested a new technique called reflection wave analysis that isolates the part of the pulse that is specific to the placenta. When combined with conventional ultrasounds, this method can diagnose circulatory problems that affect both the maternal and fetal parts of the placenta during pregnancy.

“In this study, we found that wave reflections were more prominent in women with placental vascular disease compared to healthy pregnancies,” said the team led by John G. Sled, Ph.D., senior scientist. of the translational medicine program in obstetrics and gynecology service at the hospital. “This was true for both maternal vascular malperfusion (MVM) and fetal vascular malperfusion (FVM).”

To assess whether the use of wave reflection analysis with Doppler ultrasound could increase the diagnosis of placental pathology, the team, funded by the National Institute of Health Eunice Kennedy Shriver National Institute of Child Health and Human Development, performed a standard clinical ultrasound on 241 women aged 18 to 45 years. who were between the 26e and 32nd weeks of pregnancy. Of this group, 36 women had been diagnosed with MVM, 16 had been diagnosed with VFM, and 40 were considered healthy controls. The remaining 149 women had nondiagnostic findings or rare placental diagnoses.

Based on their analysis, women with MVM or FVM were significantly more likely to have adverse pregnancy outcomes, such as preeclampsia or short stature for gestational age births, than women without placental pathologies. In addition, women with MVF also had high rates of umbilical cord abnormalities, including entanglement at childbirth, small diameter of the cord (less than 8mm), and hypercoiling.

In addition, they found that women with placental vascular pathologies had stronger wave reflections than healthy controls. According to their assessment, the first harmonic coefficients were elevated in women with MVM and FVM by 55% and 41%, respectively. These higher coefficients indicated that there was one or more distal sites of high hemodynamic impedance and / or large impedance mismatch, the team said. They suspected the capillaries in the terminal villi because the structure of the villi is abnormal in both MVM and FVM.

With clinical parameters derived from ultrasound, the team determined that the umbilical artery pulsation index was significantly increased by 48% compared to healthy controls, and the uterine artery pulsality index was increased by 77%, and the cerebroplacental ratio was significantly reduced by 35% in the MVM group. In addition, FVM women had no significant differences in uterine or uterine artery pulsality index or cerebroplacental ratio.

Taken together, the team said, these findings offer diagnostic benefits.

“The predictive performance of the first harmonic reflection coefficient was moderate. The combination of wave reflection coefficient with other parameters used clinically for monitoring (i.e., umbilical and uterine artery pulse index, fetal biometry, and maternal blood tests) has the potential to improve performance. diagnosis of placental pathologies, ”they said.

If a woman is confirmed to have an increased first harmonic wave reflection coefficient, a differential diagnosis can determine whether she had MVM or FVM pathology based on whether she had an elevated uterine or uterine pulsation index. Gestational age would then determine the next course of action, such as more intensive fetal monitoring or an emergency cesarean.

Overall, the team said, these results are particularly promising for women with VFM because there is currently no reliable method of detection.

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