The Study Of Detecting Placental Vascularization In Hypothyroidism During Pregnancy By Three-dimensional Power Doppler Ultrasound

Objective:To investigate the characteristics and clinical value of placental blood perfusion in hypothyroidism during pregnancy,three-dimensional power Doppler ultrasound（3DPD）was used to detect placental vascularization index（VI）,flow index（FI）and vascularization flow index（VFI）in the second or third trimester of pregnancy with hypothyroidism.Methods:44 pregnant women who underwent ultrasound examination and clinically diagnosed hypothyroidism in The First Affiliated Hospital of Guangxi Medical University from June 2019 to January 2020 were selected as hypothy-roidism group.36 pregnant women with normal prenatal ultrasound examination and without complications were selected as normal pregnancy group.The ratio of peak systolic velocity to end diastolic velocity（S/D）,pulsatility index（PI）and resistance index（RI）of fetal umbilical artery were measured by two-dimensional ultrasound.The placental VI,FI and VFI were measured by three-dimensional power Doppler ultrasound.The data of maternal age,gestational age,gestational age of delivery,neonatal birth weight and pregnancy condition were collected.Results:1.There were no statistically significant differences in maternal age,gestational age,gestational age of delivery,cesarean section rate,neonatal Apgar score and neonatal birth weight between hypothyroidism group and normal pregnancy group（P>0.05）.2.Placental VI,FI and VFI in hypoth-yroidism group were significantly lower compared with normal pregnancy group（P<0.05）.3.The fetal umbilical artery S/D,RI and PI in hypothyroidism group and normal pregnancy group were in normal range.But the fetal umbilical artery S/D and RI in hypothyroidism group were lower than that in normal pregnancy group（P<0.05）.PI of umbilical artery in two groups were not statistically different（P>0.05）.4.There was a positive correlation between maternal serum free thyroxine（FT₄）and placental VI,FI and VFI（r_s=0.275,r_s=0.226,r_s=0.298,P<0.05）.Placental VI,FI and VFI were not correlated with thyroid stimulating hormone（TSH）（r_s=-0.135,r_s=-0.032,r_s=-0.136,P>0.05）.Umbilical artery S/D,PI and RI were not correlated with FT₄and TSH（FT₄:r_s=0.221,r_s=0.146,r_s=0.175,P>0.05;TSH:r_s=-0.019,r_s=-0.078,r_s=-0.011,P>0.05）.5.The means of placental VI,FI and VFI of overt hypothyroidism group,subclinical hypothyroidism group,hypothyroxinemia group and normal pregnancy group were not all equal（P<0.05）.Multiple comparisons between those groups showed that there was at least one significant difference in placental VI,FI and VFI between normal pregnancy group and any hypothy-roidism subgroups（P<0.05）.There was no significant difference in placental VI,FI and VFI between hypothyroidism subgroups（P>0.05）.6.The overall incidence of pregnancy complications in hypothyroidism group was higher than that in normal pregnancy group（P=0.038）.7.In hypothyroidism group,placental FI with pregnancy complications was lower than those without pregnancy complications（P=0.036）,but there was no significant difference between VI and VFI（P>0.05）.Conclusions:1.The degree of placental vascularization in hypothyroidism group was lower than that in normal pregnancy group,and there was no significant difference among hypothyroidism subgroups.2.Both 3DPD and two-dimensional Doppler ultrasound could evaluate the placental function of hypothyroidism pregnant women,but the specificity of umbilical artery blood flow spectrum was poor,and there was no significant correlation with thyroid hormone.Placental VI,FI and VFI were positively correlated with FT₄,so3DPD could better evaluate placental function.3.The incidence of complications in hypothyroidism group was higher than that in normal pregnant group,and placental blood perfusion was lower when complications occurred in hypothyroidism group.