Analysis And Application Of Thickening Of Nuchal Translucency In Prenatal Diagnosis

Objective:To explore the application of karyotype analysis combined with chromosomal microarray analysis(CMA)technology in the thickening of fetal neck transparent layer(nuchal translucency,NT),and the analysis of the detection of chromosomal abnormalities.Methods:A total of 46,713 pregnant women who underwent NT thickness measurement at the Anhui Maternity and Child Health Hospital from January 2017 to June 2020 at 11-13+6 weeks of gestation.Ultrasound revealed NT≥2.5mm,a total of891 cases(1.91%),of which nuclear A total of 411 cases were combined with CMA by type analysis.This study included these 411 pregnant women into the study and divided them into the following five groups according to different NT thickness measurements:2.5～2.9mm group(119 cases),3.0～3.4mm group(163 cases),3.5～4.4mm group(85cases),4.5～5.4mm group(26 cases)and≥5.5mm group(18 cases);In addition,according to the different indications of prenatal diagnosis,they were divided into a simple NT thickening group(319 cases),and NT thickening combined with other groups(including advanced age,abnormal serological screening,and history of adverse pregnancy)(92 cases).Use SPSS23.0 software for data analysis.Measurement and counting data are expressed as x±S and%,respectively,andc~2test is used for analysis,ROC curve is used to calculate the area under the curve,the best cut-off value for invasive inspection is determined,and the trend test is judged.The link between abnormal NT thickness and abnormal chromosomes.Results:1.Among the five groups of fetuses with thickened NT,the rates of chromosomal abnormalities detected by karyotype analysis were 9.24%(11/119),9.82%(16/163),20.00%(17/85),and 26.92(7/26),respectively.33.33%(6/18),the difference within the group was statistically significant(P<0.05);the abnormal rates of chromosomes detected by CMA were 12.61%(15/119),15.34%(25/163),21.18%(18/85),34.62%(9/26),50.00%(9/18),the difference within the group was statistically significant(P<0.05);and the risk of fetal chromosomal abnormalities increased with the thickness of NT measurement Gradually increase(Ptrend<0.001).2.The detection rate of CMA chromosome abnormality was 18.49%(76/411),which was 4.62%higher than the 13.87%(57/411)of karyotype analysis.Among them,karyotype analysis showed no abnormalities,but CMA detected 21 cases of chromosome abnormalities,and karyotype analysis found that there were structural abnormalities in chromosomes(1 case of inversion and translocation),and CMA did not prompt.3.In the fetuses with NT≥2.5mm included in this study,the two methods were combined to detect a total of 78 abnormal chromosomes,and the positive rate was18.98%(78/411).4.Both detection methods detected 29,10,2 cases of 21,18,and 13-trisomy syndromes,and 8 cases of abnormal number of sex chromosomes.Among them,karyotype analysis and CMA both had the highest probability of detecting Down syndrome,accounting for50.88%(29/57)and 38.16%(29/76)respectively.5.The probability of chromosomal abnormalities in the NT thickening group was15.67%(50/319)lower than 30.43%(28/92)in the NT thickening combined with other groups(P=0.001).In the pure NT thickening group,the chromosomal abnormality rate(4.35%,4/92)when the NT thickness is 2.5～2.9mm was significantly lower than that of the NT thickness 3.0～3.4mm group(13.39%,17/127)(P<0.05).6.The area under the ROC curve(0.707,0.686)of the pure NT thickening group and the NT thickening combined with other groups showed that when the cut-off values of invasive examination were 3.05 and 2.85,the sensitivity was 0.857,0.833,and the specificity was 0.517,0.429,and the Youden index is 0.374 and 0.262.Conclusions:1.The risk of fetal chromosomal abnormalities gradually increases with the increase in the thickness of NT measurement.2.CMA combined with karyotyping can improve the detection rate of chromosomal abnormalities in fetuses with NT thickened,which is worthy of clinical promotion.3.Down syndrome is the most common in fetuses with abnormal NT thickness and abnormal chromosomes.4.Pure NT thickening and NT thickening combined with others,combined with clinical practice,it is recommended to take 3.0 and 2.5mm as the cut-off value for invasive examination to increase the detection rate while reducing excessively invasive operations.