ObjectiveTo explore the clinical application value of the ultrasonic soft indexes in the diagnosis of fetalchromosomal abnormalities.MethodsThe data of 513 cases of single pregnancy with positive soft indexes but no definitestructural malformation were retrospectively analyzed. The correlation between ultrasonic soft indexes and fetal chromosomalabnormalities was analyzed by binary Logistics regression

and the receiver operating characteristic（ROC）curve was drawn toanalyze the screening value of ultrasonic soft indexes for chromosomal abnormalities.ResultsAmong the 513 fetuses

therewere 457 fetuses with single positive ultrasonic soft index

and 56 fetuses with two or more positive ultrasonic soft indexes.Theoverall incidence of chromosomal abnormalities was 17.74%（91/513）

and the incidence of chromosomal abnormalities infetuses with two or more ultrasonic soft indexes positives was 28.57%（16/56）

which was higher than that in fetuses with singlepositives ultrasonic soft index（16.41%

75/457）

and the difference was statistically significan（tP<0.05）.Binary logistic regressionanalysis showed that the screening value of nuchal translucency（NT）thickening

abnormal nasal bone and single umbilicalartery for chromosomal abnormalities were significantly higher than that of other ultrasonic soft indexes（all P<0.05）

thesensitivity were 46.2%

20.9%

17.6%

the specificity were 86.5%

90.8%

88.2%

and the area under the curve were 0.663

0.558

0.529

respectively. The area under the curve of combined application of NT thickening

abnormal nasal bone andsingle umbilical artery was 0.751

which was statistically significant compared with the single ultrasonic soft index（P<0.05）.ConclusionIn the cases with positive ultrasonic soft indexes

the NT thickening

abnormal nasal bone and single umbilicalartery screening for chromosomal abnormality are of high value

and the combined application of these three can improve thediagnostic efficiency.