| Background:Clinical data showed that many diseases can get important informations from the face of the patients. Intracranial pressure increased lead to "sunset" sign, mitral stenosis could cause "mitral valve face", Down syndrome could be away from the wide eyes, low nose and so on. Similarly, we could improve the diagnosis of a disease associated with the performance of facial structural characteristics of the patients. Inspired, fetal prenatal diagnosis of structural abnormalities and chromosomal abnormalities diseases could also be observed by the fetus special facial abnormalities to reach a higer screening effect. In contrast with the adult facial plane, the fetal face is characterized of bulge which mainly be affected of jaw development. Structural abnormalities such as small jaw, maxillary hypoplasia, the alveolar ridge fracture could affect the degree of facial bump; In addition, chromosomal abnormalities were ofen mergered above structural abnormalities also led to facial plane change. Jaw abnormalities in the fetal period and after birth would bring varying degrees of physical and psychological problems. Jaw abnormalities often associated with abnormal swallowing, could cause excessive amniotic fluid, postpartum affect breathing and feeding; after birth could lead to language, chewing, orthodontic problems, and could cause varying degrees of psychological problems.For the evaluation of fetal facial contours needed some markers which would be standarded, relied on, and followed by clinical popularity and contrasted measurement. On the current development of ultrasound technology, three-dimensional ultrasound could be clear and intuitive, comprehensive display the relationship between facial shape and adjacent to structure, could supplement the two-dimensional ultrasound, could improve the detection rate of the facial malformations such as eyes from too wide or too close, too small jaw, nose valgus and etc. Three-dimensional ultrasound had become an essential tool for defining exact sagittal section in the first-trimester of pregnancy. However, in prenatal, the proper and simple ultrasound evaluation method to diagnosis of facial contours was still scarce, still needed some simple and reproducible, and straightforward surface markers did not be prejudiced of bone structure, and needed to consider the special acoustic perspective.Riedel 1952 made a defined of point A-nasal-point B (ANB) angle (nasion is the most frontal and nasal front crossing point), it used to evaluate the diagnosis for maxillary correction, prognosis, treatment planning, and it made a promoting role in prenatal ultrasound assessment of fetal facial contours. In recently years, some studied by collecting data to rename normal prenatal ANB angle to maxillary-nasion-mandible (MNM) angle, it means MNM angle could be as a tool to estimation for fetal convex contour in the second and third trimester of pregnancy.Vos FI, de Jong-Pleij EA with their mates confirmed MNM is a better indicator in the second and third trimester of pregnancy to assess fetal facial contour abnormalities, diagnostic special facial anomalies. Facial profile (FP) defined by connecting the mandible edge midpoint and bridge of the nose, was to describe the face punch visual indicator.These indicators as a good markers response facial abnormality especially jaw, provided a good reference prompt diagnosis in the second and third trimester for no obvious structural abnormalities of chromosomes, especially with the special facial features of chromosomal diseases.Often accompanied by special facial features of chromosomal disorders, mainly abnormal chromosome aneuploidy, such as trisomy 21 (also known as Down syndrome), trisomy 18 and trisomy 13, was the most common chromosomal disease. The incidence of clear pregnancy was about 3% -4%, and the incidence risk also increased with maternal age increased. Aneuploidy abnormal is also the focus requirements screening disease of prenatal and postnatal care. However, the ratio of a typical deformity of aneuploidy abnormal fetal was not high, to trisomy 21, for example, only 25-33% of fetal prenatal ultrasound can detect obvious structural deformities. Currently, in the first trimester of pregnancy (means crown-rump length is 45-84mm), ultrasound screening nuchal translucency (NT) joint screening serology, Down syndrome and trisomy 18 both had an independent risk rate, but there were still some misdiagnosis rate and high false positive rate, for trisomy 18 as an example in the United States missed rate 12 weeks of gestation was 72%.18 weeks was 65%. Among the population the rate of misdiagnosis of fetal life could not be underestimated, while in our country, not all pregnant women did aneuploidy screening in the first trimester of pregnancy, and screening efforts had the larger gap; with the opening of two-child policy and increased maternal age, the decline in the intensity of serological tests, which means that fetal aneuploidy prenatal screening is facing new and serious situation. Therefore, scholars were still committed to the continuous development of ultrasound technology to study new directions and new indicators to improve the detection rate of aneuploidy abnormal in the first trimester of pregnancy and reduce the rate of misdiagnosis and birth defects in children.Aneuploid abnormal fetals were present a common characteristic, that was obvious abnormal facial features, such as the features of trisomy 21 were flat face, widen eyes away and bridge collapse, and there were a small jaw, cleft lip and palate, flat nose, small ears low ears and other features of trisomy 18. MNM previously described as an effective indicator to assess the development of the jaw, so in theory MNM could evaluate special facial contours of aneuploidy abnormal fetal. At present there were studies confirmed the value of MNM assessment of fetal facial contours abnormalities in the second and third trimester of pregnancy. But the role and clinical value of MNM during the first trimester (CRL45-84mm) yet have a clear report.Trisomy 18 than other aneuploidy abnormalities performed typical abnormal facial features (small jaw, flat surface, oblique amount), the most common was micrognathia, could be up to 70%. The incidence of trisomy 18 in live births was about 1/3000, but almost one quarter of trisomy 18 fetus during the first trimester of pregnancy did not screening any structural abnormalities, just only waited for a higher sensitivity of 20 week ultrasound to detect major structural abnormalities such as heart defects, limb deformities, kidney malformations,etc..The current development of ultrasound equipment and progress skill of ultrasound screening technology in first trimester of pregnancy, we found many of the major and minor abnormalities associated with trisomy 18, such as lack of nasal or nasal bone hypoplasia, NT thickening had been able to observe during the first trimester, whether through the related indicators reacted facial contours, such as the detection rate of MNM, facial profile(FP), nasal bone length (NBL) was observed to improve early pregnancy trisomy 18, and yet to study.Purpose:Some scholars have suggested, the maxillary-nasion-mandibular (MNM) angle could be used as an evaluation indicator of fetal face in second and third trimester, during this study, we collected during MNM angle data in the first trimester of pregnancy to see whether there was a significant differences with in second and third trimester, and to assess its the clinical application of the feasibility and reproducibility in first trimester of pregnancy; in addition to retrospectively analy the diagnosis of trisomy 18 fetal to assess the value of the relevant indicators reacted facial contours--MNM, FP, NBL in early diagnosis of trisomy 18.Methods:A total of 5300 fetuses in their early pregnancy (crownrump length 45-84 mm) were screened in our hospital from January 2013 to December 2015.This study was conducted with approval from the Ethics Committee of Qianfoshan Hospital Affiliated to Shandong University. All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions. Informed consent was obtained from all patients for being included in the study.In order to ensure the repeatability, all the indicators in all cases were completed by two experienced ultrasonologists under the conditions of not knowing the gestational age and the other ultrasonologist’s measurement data. The 2D ultrasound and 3D volume collection were performed targeting the fetal head standard sagittal section, to measure MNM. Median sagittal section of the fetus in a natural posture stretch, the plane perpendicular to the skin with the back of the fetal neck, the fetal midline structures, such as diencephalon, hindbrain, nasal bone, spine etc. and stored these images. The multi-plane mode of ultrasound could much more accurately display the sagittal section, and only the real fetal facial median sagittal section images were selected for the analysis using the 4D view software. In this study, facial profile image should display the forehead, nasal bone, and mandible, and the maxilla should be displayed as a single horizontal line without jugal bone or mandibular branch.Following-up involved pregnant women, there was a retrospectively analyz on trisomy 18 fetuses which were diagnosed by amniotic fluid or cord blood puncture, eventually with chromosome, reviewed the two-and three-dimensional ultrasound images of abnormal fetal stored in first-trimester, and then analysised by 4D view software to obtain fetal facial median sagittal section (section requires ibid.), at the same time measured MNM angle, FP, NBL. Test datas in this study were compared and analyzed with relevant data of MNM angle in last study and Vos FI reported about aneuploidy fetuses.The t-test was used to analyze the difference among the easurement values, with P< 0.05 considered as statistically significant. EXCEL2003 and SPSS 19.0 were used to analyze the datas.Results:MNM was obtained from a total 4823 fetuses (91%), and the rest fetuses could not be measured due to fetal overflexion, nasal bone deletion, or poor maxillary display. There was no significant difference in the measurement values between the two ultrasonologists (P= 0.94).The average MNM in the study subjects was 11.00° ± 2.58° SD. Different operators in different groups measured value difference is less than 1.1 °.The gestational age and MNM showed no consistency(P= 0.15). Not with the gestational age increases or decreases. There was no statistical significance between the measurement data of this study and Vos et al.(P= 0.62).Referring to the MNM range in the second trimester of pregnancy proposed by Vos et al. Total of 42 cases of trisomy 18 were analyzed efficiently. Furthermore, MNMs in fetuses with trisomy 18 were all higher than the 95th percentile of the measurement data in this study. The sensitivity of increased MNM on the abnormal detection of trisomy 18 was 54.7%, and the specificity was 97.4%.FP line in 46.1% cases was negative,51.2% was 0, just a case was a positive. FP line did not change significantly with the change of gestational age. For tririsomy 18, FP line detection rate was 46%.NBL was 1.7+/-0.16 SD in trisomy 18, NBL with gestational age had a significant correlation (P<0.001). For trisomy 18, NBL detection rate was 63.7%.Follow-up cases of patients none measured three marks were normal, at least one was the exception. The three marks combinational detection rate was about 92.7%.When the NBL, MNM angle, FP line contrasted, NBL with MNM angle and FP line had no significant correlation, MNM angle and FP line were correlated.Conclusion1、 MNM was a potential tool that could objectively evaluate the anteroposterior relations of maxilla and mandible in early pregnancy so as to assess the fetal facial profile. Early pregnancy (CRL45-84mm) MNM angle measurement has good feasibility and repeatability.2、When ultrasound screening found no obvious structural abnormality in the first-trimester of pregnancy, only found fetal nasal bone hypoplasia or absence,we should raise vigilance; at the time the measurement of MNM angle and FP line played an affirmative role of trisomy 18.3、MNM angle and FP line could be independently of pregnancy, could be used as a fixed mark application, could be applied in early pregnancy. |
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