| Objective:to investigate the detection efficiency of common chromosomal abnormalities in fetuses by selecting different further prenatal screening programs based on the risk results of maternal serological screening in the second trimester,and to guide clinical selection of screening programs that are economical,simple,high detection rate,low rate of missed diagnosis and low rate of false positive.Methods:application of time-resolved immunofluorescence technique in 24986 cases of pregnant 15～20+6 w to maternal serologic screening of pregnant women duplex screening method to detect the womb free beta human chorionic gonadotropin(free-beta HCG)and AFP(AFP)concentration,combined with matermal age,gestational age,weight,history of pregnancy,the presence of diabetes,smoking and other factors,using Lifecycle3.2 software automatically calculates risk value of the DS and ES.According to the risk value,the population was divided into high-risk group(group A)and critical risk group(group B),and then according to the different follow-up inspection schemes,the high-risk group(group A)was divided into the group of direct amniocentesis for high-risk serological screening(group A1)and non-invasive screening group for high-risk serological screening(group A2).The critical risk group(group B)was divided into the soft index screening group(group BI)and the non-invasive screening group(group B2)according to the different follow-up screening schemes.The positive rate,sensitivity,specificity and health economics evaluation of screening programs in each group were compared and analyzed after the follow-up of pregnancy outcomes in each group,so as to understand the impact of different screening programs on the detection efficiency of common fetal chromosomal abnormalities.Results:① 24986 pregnant women in the second trimester of maternal serological screening detected 1558 cases in high-risk group A,with A positive rate of 6.2%,3123 cases in critical risk group B,A positive rate of 12.5%,with A low risk of 20305 cases.The high-risk group received direct amniocentesis(group A1)in 390 cases,and NIPT(group A2)in 1001 cases were rejected for amniocentesis,and 167 cases were rejected for further examination and lost follow-up.In the critical risk group B,1479 cases were selected for soft index screening(group Bl),901 cases were selected for NIPT(group B2),and 743 cases were rejected for examination and lost to follow-up.② In group A1,1 case of DS,2 cases of ES and 14 cases of other chromosome abnormalities were confirmed by direct amniocentesis.In group A2,24 cases with high risk of NIPT were detected,9 cases of DS were confirmed by amniocentesis,2 cases of ES,6 cases of other chromosome abnormalities,1 case of 18-trisomy syndrome and 1 case of small fragment deletion of chromosome 6 were missed in the low risk group of NIPT.The detection rates of fetal chromosomal abnormalities in the high-risk A1 and A2 groups were 100%and 89%,respectively,with χ2=6.74,p=0.01.The differences were statistically significant.③ Group B1 detected 60 cases with positive soft indicators,2 cases with DS confirmed by amniocentesis,2 cases with other chromosomal abnormalities,and 2 cases with missed diagnosis of DS in negative soft indicators.In the B2 group,15 cases with high risk of NIPT were detected,and 1 case of DS,1 case of ES and 2 cases of other chromosome abnormalities were confirmed by amniocentesis.The detection rates of fetal chromosomal abnormalities in the high-riskB1 and B2 groups were 60%and 100%④According to the single serological screening results to guide prenatal diagnosis,high risk group A prenatal diagnosis,critical risk group B regular prenatal examination,can detect 14 cases of target disease(DS in 10 cases,ES in 4 cases),other chromosome abnormalities in 20 cases,A program of the detection rate of target disease is 63.6%;According to the serological screening results,the critical risk group B combined with ultrasound soft index screening or NIPT was conducted.The program of group A+B detected A total of 18 cases of target diseases(13 cases of DS,5 cases of ES)and 25 cases of other chromosomal abnormalities,with the detection rate of target diseases reaching 81.8%.The detection rates of the two schemes were compared,χ2=6.14,p=0.01,P<0.001,and the difference was statistically significant.⑤The ROC curve was used to meet the condition of false positive rate<0.08,the choice of the sensitivity of the highest truncation value of DS risk truncation value is 1/404,at this time the sensitivity is 0.7647,false positive rate is 0.0743.⑥In terms of health economics evaluation,the cost of diagnosing 1 case of chromosomal abnormalities in group A1,group A2,group B1 and group B2 was RMB 209,530,RMB 201,003,RMB 459,323 and RMB998,417,respectively.The cost of the A2 scheme group was the least and that of the B2 scheme group was the most.Conclusion:① prenatal screening is an important means to guide prenatal diagnosis,especially combined screening program is better than a single screening program.②NIPT is currently the most sensitive screening technology for autosomal aneuploidy screening,but there are still false negative rate and false positive rate(although very low),so we should pay attention to the limitations of NIPT.NIPT cannot replace prenatal diagnosis as the final diagnosis.In the case of high cost of NIPT detection,it is not recommended to be used as a first-line screening method.However,with the continuous development of sequencing technology and more and more extensive application,the price of NIPT is bound to be further reduced.Only when the cost-benefit ratio is greatly improved,will it be more conducive to clinical wide application.③In the double serological screening,when the false positive rate is less than 8%,the high risk cutoff value of 21-trisomy syndrome can be selected as 1/404 to obtain the highest detection rate.④Through the detection rate of different prenatal screening strategies and evaluation of health economics,when serological screening results for high risk,A1 screening strategy is the first choice,and in pregnant women for prenatal screening and diagnosis technology fully knowledge can choose A2 scheme,can effectively reduce the miscarriage of interventional surgery and reduce anxiety among high-risk pregnant women and their families,and improve prenatal diagnosis;When serological screening results are middle risks,B2 scheme is recommended and NIPT can be selected to achieve more effective detection rate.In economically backward areas,B1 scheme should be actively promoted as a supplement when NIPT is economically restricted. |
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