Shunt rate of ductus arteriosus and ductus venosus in middle and late fetuses and their application value in the evaluation of fetal growth restriction

Objective: To explore the Shunt rate of ductus arteriosus (DA) and ductus venosus (DV) in middle and late fetuses and their application value in the evaluation of fetal growth restriction (FGR).Methods: In this retrospective observational study, we reviewed the clinical data of the patients who admitted to the Second Affiliated Hospital of Wenzhou Medical University from September 10, 2017 to November 27, 2018, and finally included 44 normal women at 28-31 weeks of pregnancy (Normal group) and 15 pregnant women with fetal growth restriction (FGR) within 28-31 weeks of gestation (FGR group). We measured blood flows of the DA (Q(DA)), pulmonary artery (QP(A)), DV (Q(DV)), and umbilical vein (Q(UV)) and the shunt rates of the DA and DV (Q(DA)/Q(PA) and Q(DV)/Q(UV), respectively) in all fetuses. We compared the mean variables between groups using the Normal group means as the normal reference values for analysis.Results: DA shunt rate was linearly and positively correlated with gestational age (Y=1.455X+2.787; r=0.767, P<0.01), while the DV shunt rate was linearly and negatively correlated with gestational age (Y=-2.791X+126.885; r=0.761, P<0.01). The DA shunt rates (Q(DA)/Q(PA)) of fetuses in the normal were higher than those in the FGR groups, but the differences between the two groups were not statistically significant (P > 0.05). The DV shunt rates (Q(DV)/Q(UV)) of fetuses in the normal were significantly lower than those in the FGR groups (P < 0.05). The DV shunt rates in the FGR group were significantly higher than those in the normal group with differences being statistically significant at 30-30(+6) and 31-31(+6) gestational weeks (P < 0.05) The receiver operating characteristic curve (ROC curve) showed that the higher the shunt rate, the worse the birth outcome of a fetus with FGR.Conclusions: The DV shunt rate in middle- and late-stage fetuses can predict the fetal birth outcome, and the higher the shunt ratio, the worse the birth outcome of FGR fetuses.