Study On Fetal Structural Abnormalities And Chromosomal Abnormalities With Prenatal Ultrasonography

Objective To investigate the diagnostic value of prenatal ultrasound for fetal structural abnormalities,distribution of fetal structural abnormalities and the reasons of misdiagnosis. And on this basis,to explore the correlation between fetal structural abnormalities,ultrasonic soft markers and chromosomal abnormalities.Fetal chromosomal abnormalities were found more by using the method of the combination of maternal serum markers and ultrasonic examination.To do this,the time of prenatal screening was ahead from the second and third trimester to first trimester and to solve the problem of late screening,low detection rate and invasive in screening fetal chromosome abnormalities.Method 1. There were 266803 pregnant women screened by prenatal ultrasound with variety of means form 2010 January to 2014 June in our hospital. The types and quantities of fetal structural abnormalities and gestational age were recorded. Fetal structural abnormalities were classified according to human anatomy system.Follow up cases of misdiagnosis and the reasons of misdiagnosis were analyzed. 2. 1376 pregnant women with fetal structural abnormalities or ultrasonic soft markers were punctured to obtain amniotic fluid and umbilical cord blood for examination of fetal karyotype. The types and quantities of fetal chromosomal abnormalities were recorded. The features of all ultrasonic soft markers were analyzed. 3. 6000 cases of pregnant women in the first trimester were examined by the combination of ultrasonic examination and maternal serum markers. Only pregnant women with high risk were punctured to obtain amniotic fluid and umbilical cord blood for fetal karyotype. The types and quantities of fetal structural abnormalities and chromosomal abnormalities were recorded. The features of all ultrasonic soft markers in all kinds of chromosomal abnormalities and the correlation between prenatal ultrasonic soft markers and heart abnormalities were analyzed. The detection rate, sensitivity, specificity of ultrasound screening in the first trimester pregnancy were calculated.Result 1. A total of 3101 cases(4171 positions) were diagnosed as fetal structural abnormalities by prenatal ultrasound; the detection rate was 11.62‰. In terms of anatomy systems, the top five were cardiovascular system abnormalities, the central nervous system abnormalities,facial abnormalities, urinary system abnormalities, and respiratory system abnormalities. In terms of single abnormalities, the top five were cleft lip and palate, ventricular septal defect, kidney seeper, spina bifida, and atrial-ventricular septal defect. 856 cases(947 positions) of fetal structural abnormalities were missed and the misdiagnosis rate was 3.21‰. The top five of missed deformities were polydactylia/symphysodactylia, ear deformities, hypospadias, foot abnormalities, and ventricular septal defect. 2. There were 66 cases of abnormal chromosome detected in 1376 cases of chromosomal specimen,and the abnormal rate was 4.72%. Sensitivity of ultrasound screening for chromosomal abnormalities was 60.61%.Specificity was 76.64%.The positive predictive value was 11.56%. The detection rate of chromosomal abnormalities in positive cases of ultrasound screening is higher than in negative cases(the former 40/346, the latter 11.56%, 26/1030, 2.82%). Positive predictive value of fetal chromosomal abnormalities from high to low is: multiple fetal structural malformations 25.4%, multiple ultrasound soft markers 11.9%, single structural deformity 10.3%, single ultrasonic soft marker 7%. The study showed that cystic hygroma, heart defects, limb abnormalities, skin edema, pleural effusion and fingers overlapping have high correlation with chromosomal abnormalities. 3. Among 6000 pregnant women who took examinations of maternal serum markers as well as ultrasonic screening, 326 pregnant women with high risk were detected, and among 326 pregnant women, there were 21 cases of chromosomal abnormalities detected including 9 cases of trisomy 21, 3 cases of trisomy 18, 1 cases of trisomy 13, 5 cases of Turner syndrome and 3 cases other chromosomal structural abnormalities. The detection rate of trisomy 21 was 89.9%, false positive rate 5.3%. NT was thicker obviously in the chromosomal abnormalities. There was 42 cases fetal serious malformations detected by early pregnancy ultrasound. Sensitivity of early pregnancy ultrasound screening for serious fetal malformations was 54.4%. Specificity was 99.9%. The positive predictive value was 81.2%. The negative predictive value was 99.6%. Incidence rate of NT,TR and DV were higher in cardiac malformations.Conclusion 1. The high detection rate for fetal structural abnormalities with prenatal ultrasound. showed that it is an indispensable means for the diagnosis of fetal malformation. With prenatal ultrasound it is found that the different kinds of fetal structural abnormalities have certain distribution. But it has some limitations. there is a high rate of missed diagnosis for polydactylia/symphysodactylia, microtia, and hypospadias. Ultrasound doctors should pay more attention for these abnormalities. 2. It is an effective measure to improve the detection rate of the chromosomal abnormalities with fetal structural abnormalities or ultrasonic soft markers to detect chromosomal abnormalities in the second and third pregnancy. The chromosomal invasive examination should be taken when fetuses suffered from multiple structural abnormalities,multiple ultrasonic soft markers and several special defects. 3. Early prenatal ultrasound screening is an effective means to find out severe fetal structural malformations, but it should be combined with ultrasonogrphy in the second and third pregnancy. 4. Ultrasonic soft markers(NT,DV,TR) may be related with congenital heart disease at the first trimester pregnancy.