The Clinical Value Of Ultrasonographic Soft Markers In The Second Trimester In Prenatal Diagnosis Of Fetal Chromosome Abnormalities

Objective:To investigate the relationships between ultrasonographic soft markers in the second trimester and fetal chromosome abnormalities. Assessing the clinical value of ultrasonographic soft markers in prenatal diagnosis will help to regulate and guide the work of prenatal diagnosis.Materials and methods:From January 2011 to December 2014,1448 cases in Center of prenatal diagnosis in Changzhou maternal and child health care hospital were given amniocenteses to determine the chromosome karyotypes after consultations,of which 106 cases with ultrasonographic soft markers in the second trimester.The ultrasound image and chromosome karyotype data were retrospected to analyze the relationships between the soft markers and chromosome abnormalities. The ultrasonographic soft markers in the second trimester were thickened nuchal fold,mild ventriculomegal,choroid plexus cyst,cisterna magna,echogenic intracardiac focus,echogenic bowel,mild pyelectasis,single umbilical artery,shortened humerus or femur.Results:Among 1448 cases of chromosome karyotype analyses,132 cases were found with chromosome abnormalities and the abnormal detection rate was 9.12%. 63 of 132 cases with chromosome abnormalities displayed numerical abnormalities of chromosomes,including 15 cases with trisomy 18,39 cases with trisomy 21,2 cases with 45-X and 7 cases with sex chromosome abnormality. 69 of 132 cases with chromosome abnormalities showed structural chromosome abnormalities. Among 106 cases with ultrasonographic soft markers,21 cases were found with chromosome abnormalities and the abnormal detection rate was 19.81%,18 out of 21 cases with numerical abnormalities of chromosomes,consisting 8 cases with trisomy 18,10 cases with trisomy 21;3 out of 21cases with structural chromosome abnormalities. The sensitivity,specificity,positive predictive value and negative predictive value of ultrasound soft markers in diagnosis of chromosome abnormalities was 15.91%(21/132),93.54%(1231/1316),19.81%(21/106)and 91.73%(1231/1342)respectively.Among 106 cases with ultrasonographic soft markers,the abnormal detection rate with structural abnormalitie was 42.11%(8/19) and the abnormal detection rate without structural abnormalitie was 14.94%(13/87),the difference between the two groups was statistically significant. Among 87 cases without structural abnormalitie,the abnormal detection rate with single soft marker was 9.09%(6/66) and the abnormal detection rate with multiple markers was 33.33%(7/21),the difference between the two groups was statistically significant.The soft markers of 10 cases with trisomy 21 were thickened nuchal fold,choroid plexus cyst,mild ventriculomegal,mild pyelectasis,echogenic bowel and echogenic intracardiac focus.The top four positive likelihood ratio were thickened nuchal fold,mild ventriculomegal,mild pyelectasis and echogenic bowel.The soft markers of 8 cases with trisomy 18 were choroid plexus cyst,thickened nuchal fold,single umbilical artery and mild ventriculomegal,in which,choroid plexus cyst was the most sensitive marker in diagnosis of trisomy 18.Conclusion:There is a close relationship between ultrasonographic soft markers in the second trimester and fetal chromosome abnormalities, especially with numerical abnormalities of chromosomes,such as trisomy 21 and trisomy 18,etc. And soft markers often suggest a higher risk of chromosome abnormalities. The pregnant women should be given prenatal diagnosis to determine fetal karyotype whose fetus with thickened nuchal fold,multiple markers,or structural abnormalitie by ultrasonic examination. Integrated evaluation combined with other prenatal diagnosis indications,such as serum in high risk,advanced meternal age,abnormal pregnancy history and family medical history,should be applied to fetus with single soft marker,to reduce the unnecessary invasive puncture.