| Chromosomal disease is divided into two categories, autosomal disease and sex chromosome disease, which is short for chromosomal genetic disorders. Chromosomal disease is mainly caused by the abnormal structure and number of chromosome, which is the main carrier of genetic material in cells. Generally, Chromosomal disease is one of the main reason for the birth defects and wai begat death Prenatal ultrasound examination with its non-invasive, repeatable, reliable advantages has became an important mean for fetal antenatal screening. Originally, fetal 21- trisomy syndrome accompanied by significant structural abnormalities accounted for only about 25%, that is to say, prenatal diagnosis of 21- trisomy syndrome through the ultrasound counted for only about 25%, nearly 75% of 21-trisomy syndrome was missing. This study was to observe the micro structural changes of 21- trisomy syndrome by prenatal ultrasound, which is the ultrasound’s "soft index" and be regarded as the risk factor of 21- trisomy syndrome, known as the genetic ultrasonography. Frontomaxillary facial angle in ultrasound performance of the normal fetus and aneuploid fetus(especially 21-trisomy) is different, and the index will decrease with the Crown-rump length increase. In addition, the association between facial angel, the neck with the thickness of Nuchal translucency(NT) and serum markers(β-h CG、PAPP – A)were not significant, suggesting that it could be used as an independent complementary indicator of aneuploidy screening.Objectives: This study is based on a large sample size to make a deep explore about the correlation between the frontomaxillary facial angle and fetal chromosomal abnormality in the north of China, and to evaluate its clinical application value!Methods: From January 2015 to June 2016, the pregnant women between gestation 11W~41W are scaned and measured indexes about fetal NT, NBL, PT and FMFA, who are divided into three groups, the first group between gestation 11~13W,the second group between gestation 14~28W, the third group between gestation 29~40W. For pregnant women who in gestation 11~13+ 6W, drawed normal peripheral blood samples to detect the pregnancy related protein(PAPP- A) and free h CG(f-beta HCG) On the right day of ultrasound. For high-risk patients, though amniocentesis or umbilical cord puncture for cell culture and chromosome karyotype analysis to determine if chromosomal abnormalities(aneuploidy and structural abnormalities in children) after informed consent.The data were analyzed by SPSS19.0 statistical software, if measurement data accord with normal distribution, performance by x_±s, if don’t, performance by M(P25-P75). The comparition of data were analyzed with t test or rank sum test, and using spearman to analyse the correlation between FMFA and NT, NBL, PT, PAPP-A, β-h CG. Using receiver operating characteristic curve(ROC) to evaluate the frontomaxillary facial angle measurement as a identification of fetal abnormal chromosome’s specificity and sensitivity. All statistical tests were two-sided test, and the calibration of test is 0.05.Results: The clear images of the frontomaxillary facial angle, nuchal translucency, nasal bone length and prenasal thickness about three fetuses groups were obtained.1.Compare each index between normal and abnormal group of 11-13 weeks, all the differences among FMFA, NT, NBL, PT, PAPP-A and β-HCG were significant, performance that the indexes of abnormal group were higher than that of the normal group.2. Compare each index between normal chromosome group and abnormal group in gestation 14-27 weeks: frontomaxillary facial angle has significant statistically differences(P<0.001);while nasal bone length and nose thickness don’t.(P>0.05).3. Compare each index between normal chromosome group and abnormal group in gestation 28-40 weeks:there were statistically significant differences in the frontomaxillary facial angle and nasal bone length(P<0.001); while there was no significant difference in the prenasal thickness(P>0.05).4. Compare FMFA between the normal group and abnormal group in three different gestational periods : the normal group varied with gestational weeks, the index of FMFA will decrease with the increase of gestational weeks(χ2=57.991,P<0.001); while the abnormal group will not change with the gestational weeks(χ2=4.083,P=0.13).5.Compare NBL between the normal group and abnormal group in 14-27 weeks and 28-40 weeks : the normal group changes with gestational age, and the index will increase with gestational weeks increase(Z=-17.272, P < 0.001), while the abnormal group does not change with gestational weeks(Z=-1.524, P =0.130),6.Compare PT between the normal group and abnormal group in 14-27 weeks and 28-41 weeks : the normal group changes with gestational age, and the index increases with gestational weeks(Z=-16.920, P < 0.001), the difference was statistically significant; the abnormal group also changes with gestational age, and the index increases with gestational weeks((t=-4.337, P <0.001), the difference was statistically significant.7.All the correction of FMFA and NT(r=-0.013, P =0.852), FMFA and PAPP-A(r=-0.018, P =0. 802), FMFA and β-h CG(r=0.118, P =0.098), FMFA and NBL(r=-0.032, P =0.440), FMFA and PT(r=0.047, P =0.251) have no statistical significance.8. When regard FMFA as a diagnostic index for evaluation and analysis in gestational 11-13 weeks, the FMFA cut-off value was 88.1700°, the area under the ROC curve was 0.9898,95%CI(98.1% ~ 99.8%). When regard FMFA as a diagnostic index for evaluation and analysis in gestational 14-27 weeks, the FMFA cut-off value was 86.9400°, the area under the ROC curve was 0.9632,95%CI(91.5% ~ 100%). When regard FMFA as a diagnostic index for evaluation and analysis ingestational 28-40 weeks, the FMFA cut-off value was 88.4300°, the area under the ROC curve was 0.9871,95%CI(97.2% ~ 100%).Conclusion: 1.FMFA and NT, NBL, PT, PAPP-A β-h CG were not significantly associated.2.In the early, middle and late gestational age, the FMFA of the normal group will change with the gestational weeks, performance for FMFA becoming smaller with the increase of gestational weeks, while the FMFA of the abnormal group will not change with the gestational weeks.3. There were significant differences in the frontomaxillary facial angle between the abnormal fetal group and the normal group. Frontomaxillary facial angle of aneuploidy fetus was significantly bigger than that of normal group.4. Compare the nasal bone length of normal group and abnormal group between gestatioal 14-27 weeks and gestatioal 28-40 weeks: the length of nasal bone will increase with gestational weeks increase in normal group, while it won’t change with gestational weeks increase in abnormal group.5. Compare the prenasal thickness of normal group and abnormal group between gestatioal 14-27 weeks and gestatioal 28-40 weeks: both the index of prenasal thickness in normal group and abnormal group will increase with gestational weeks increase..6. FMFA can be regarded as a screening index of fetal chromosomal abnormalities: the sensitivity was 94.19% and the specificity was 95.6%, which can be used as a marker for fetal chromosomal abnormalities, especially for Down’s syndrome. |
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