
Evaluation of fetal growth restriction by color Doppler ultrasound 23
Vol. 66(1): 16 - 25, 2025
an elevation in S/D, PI, and RI levels of the
umbilical artery. In severe cases, the risk of
adverse events, such as intrauterine distress,
asphyxia, and even death of the fetus, may in-
crease 11,12. In this study, the RI, PI, and S/D
levels of umbilical artery in the FGR group
were significantly higher than those of the
healthy group (p<0.05), indicating that the
blood flow in the umbilical artery of fetuses
with FGR was in a high resistance state.
According to the hemodynamic princi-
ple of fetal placental circulation, villous vas-
cular bed increases in the second and third
trimesters of pregnancy, the resistance of
fetal placental circulation and the S/D de-
crease, and the placental blood flow increas-
es accordingly, which is conducive to the
growth and development of fetuses.13 The
results of this study revealed that the S/D
value of FGR fetuses significantly increased,
probably due to prolonged hypoxia and nu-
tritional deficiencies. Moreover, fetal devel-
opment is closely related to placental blood
flow. As a result, the S/D value indirectly
reflects the fetal-placental circulation state
and intrauterine conditions. Also, the ROC
curve analysis results showed that the AUCs
of RI, PI, and S/D of the umbilical artery in
the diagnosis of FGR were 0.893, 0.893 and
0.900 (p<0.05), respectively, indicating that
abnormal umbilical artery hemodynamics
can affect the supply of nutrients to fetuses.
Regular monitoring of umbilical artery he-
modynamic changes is favorable for the early
diagnosis and clinical management of FGR.
As an important branch of the inter-
nal carotid artery, the middle cerebral ar-
tery markedly affects the changes in fetal
cerebral circulation, and its hemodynamic
alterations are closely related to fetal cra-
nial blood circulation and hypoxia 14,15. In
the case of insufficient cerebral blood sup-
ply and oxygenation, the hypoxia and isch-
emia of the fetus are aggravated, causing
damage to other organs and affecting the
prognosis 16,17. In this study, the RI, PI, and
S/D levels of the middle cerebral artery in
the FGR group were significantly lower than
those in the healthy group (p<0.05), prob-
ably because FGR activated the cerebral pro-
tective effect to self-regulate and contract
peripheral vasculature to increase the blood
supply to the heart, brain, and other vital or-
gans. As a result, monitoring the changes in
the resistance parameters of the middle ce-
rebral artery can evaluate the effect of fetal
hypoxia on FGR. The results of ROC curve
analysis herein revealed that the AUCs of RI,
PI, and S/D of the middle cerebral artery in
the diagnosis of FGR were 0.812, 0.874, and
0.910 (p<0.05), with high specificity and
Youden index. Moreover, the analysis of preg-
nancy outcomes based on the cut-off value
of RI showed that a high proportion of fe-
tuses with severe hypoxia had an RI >0.69.
Therefore, the blood flow parameters of the
middle cerebral artery can be used as indica-
tors for the prenatal ultrasound diagnosis of
FGR.
PSV/ESRV can reflect the blood flow of
the aortic arch isthmus. When a fetus has
a reduced blood supply, the body activates
the compensatory mechanism to protect im-
portant organs such as the heart and brain
and increase the perfusion of such organs,
increasing ESRV level and decreasing PSV/
ESRV 18,19. In this study, the PSV/ESRV lev-
el of the aortic arch isthmus in the FGR
group was significantly lower than that in
the healthy group (p<0.05), suggesting that
FGR can also be evaluated based on hemo-
dynamic changes in the aortic arch isthmus.
Probably, the decreased blood oxygen level
during the increase in the resistance to fetal
peripheral blood flow cannot meet the needs
of fetal growth and development, so the body
initiates a compensatory mechanism to pro-
mote dilatation to increase the perfusion of
blood flow. Also, local anaerobic glycolysis
increases in a state of hypoxia, producing
metabolites such as lactate and adenosine,
which can dilate blood vessels and reduce
cardiac output 20. Additionally, the results of
ROC curve analysis revealed that the AUC of
PSV/ESRV of aortic arch isthmus in diagnos-
ing FGR was 0.857 (p<0.05), with the sensi-