Prenatal Screening And Diagnosis Of Chromosome Aneuploidies In 381 Fetuses Of Twin Pregnancy

Objective:To analyze the efficiency of NIPT in prenatal screening of fetal chromosome aneuploidy in twin pregnancy,so as to provide reference for the clinical work of prenatal screening of fetal chromosome aneuploidy in twin pregnancy.Methods:Data of 381 pregnant women with twin pregnancy who visited the first hospital of shanxi medical university and underwent NIPT screening from June 2017 to May2019 were collected.The collected information included the pregnant woman's name,age,weight,last menstruation,method of conception,chorionic sex,ultrasound results during pregnancy,serological screening results,etc.Finally,pregnant women who chose NIPT examination signed the informed consent,collected specimens and completed NIPT.For the NIPT results,after genetic counseling was provided to high-risk people,amniocentesis was voluntarily selected,informed consent was signed,amniotic fluid specimens were collected,and karyotype analysis of amniotic fluid was completed.All twin pregnant women were followed up to 3 months after birth.Results:NIPT examination was completed in 381 cases of twin pregnancy.Of NIPT screening results for high-risk cases,4 cases(1%),including 3 cases of high risk for 21-three body,1 case of 18-three body risk,after genetic counseling,all voluntary interventional prenatal diagnosis,amniotic fluid karyotype analysis results are in conformity with NIPT screening results,including 1 case of pregnant women,after fulfilling the amniotic cavity puncture is not yet out of the karyotype results have been spontaneous abortion;After the other 3 pregnant women received genetic counseling again,2 of them chose to perform fetal reduction surgery on the abnormal fetus,and 1 of them chose to induce labor.There were 377 NIPT low-risk cases,accounting for 99%,all of whom were followed up for pregnancy outcome.Among them,368 cases(97.6%)were followed up to 3 months after the birth of the fetus.All the newborns underwent physical examination,and there was no phenotype of children with trisomy 21,trisomy 18 or trisomy 13 in the phenotype of the newborns.There were 2 cases of single live birth(0.5%)and 4 cases of spontaneous abortion(1%).There were 3 cases of induced labor,accounting for 0.8%,and no chromosome karyotype analysis was performed on the fetal tissue of abortion and induced labor.Among the 23 cases of twin pregnancy pregnant women whose fetus was found to have ultrasound soft index in prenatal ultrasound examination,3 cases were detected as high risk(13.0%)by NIPT screening fetal chromosome aneuploidy,and the result of interventional prenatal diagnosis was confirmed as 21 trisomy in one of the 2 pregnant women and 18-trisomy in one of the 1 pregnant women.The results of the remaining 20 cases of NIPT screening were of low risk,among which 4 cases were induced labor due to fetal blood transfusion syndrome,fetal growth restriction and severe pregnancy complications in the third trimester of pregnancy,3 cases had spontaneous abortion,and the remaining 13 cases were followed up.The results showed that no chromosomal aneuploidy type was found in the physical examination of newborns.There were 359 successful cases(94.2%)in the first test of NIPT test,22 failed in the first test,and 21 successful cases(5.5%)in the second test.1 case still failed,accounting for 0.3.The results of Logistic regression model analysis showed that there was a significant correlation between the weight gain and the small gestational week of pregnant women with twin pregnancy and the failure rate of NIPT test for the first time.Conclusion:NIPT has a high detection rate,sensitivity and specificity of chromosome aneuploid in fetuses of twin pregnancy,and a low false positive rate and false negative rate.NIPT is still used for prenatal screening,where false positives exist and interventional prenatal diagnosis is required when the results are highrisk.Ultrasound examination in pregnancy plays an important role in improving the detection of twin chromosome aneuploid fetus.For the screening of aneuploidy in twin pregnancy,ultrasound examination combined with NIPT can be used to screen,which can increase the detection rate,reduce the rate of missed diagnosis and reduce the unnecessary interventional prenatal diagnosis.