The Study Of Middle Cerebral Artery Peak Systolic Velovity In Fetuses With α-Thalassaemia In The First Trimester

Objective:To investigate the value of middle cerebral artery peak systolic velocity by color Doppler ultrasonography in predicting fetuses with homozygous α-thalassemia-1 in the first trimesterMethods:110 high-risk fetuses due to homozygous α-thalassemia-1 were performed with two-dimensional ultrasound and measured MCA-PSV at 11～13 weeks before undergoing the prenatal diagnosis for thalassemia gene by chorionic villus biopsy.Results:1、93 fetuses got the eligible MCA-PSV, the detectable rate of MCA-PSV was 84.5%; 2、The result of fetal α-thalassemia gene diagnosis: 18 fetuses were affected by homozygous α-thalassaemia-1, the rest were unaffected; 3、Among the fetuses,32.3% had MCA reversed end-diastolic flow, 70% was observed at 11～12 weeks; 4、The MCA-PSV of unaffected fetuses were significantly rise with the increase of the gestational age (r=0.691,P< 0.05); 5、The affected fetuses had significantly higher MCA-PSV compared to the unaffected fetuses (t=0.404, P<0.05); 6、The sensitivity、specificity、 negative predictive value、positive predictive value of MCA-PSV for the prediction of fetuses with homozygous α-thalassaemia-1 in the first trimester was 33.3%、93.3%、54.5%,85.3% respectively; 7、Twelve affected cases had a normal MCA-PSV, seven of these showed abnormal two-dimensional ultrasound images(seven cases increased cardiothoracic ratio, four cases increased placental thickness, one case insufflate echogenicity).Conclusion:1、Although the fetuses with homozygous α-thalassemia-1 had higher MCA-PSV than that of unaffected fetuses, our present study found that MCA-PSV was not very sensitive in the prediction of homozygous α-thalassemia-1, so it is not recommended that MCA-PSV be used alone in the first trimester; 2、Combine it with other ultrasound markers may improve the sensitivity of screening for homozygous α-thalassemia-1 and avoid delaying the time of diagnosis.