Application Of Ultrasound To Evaluate The Ossification Timing Of Fetal Sacral Vertebrae And Sacral Length

Objective:Application of ultrasound to evaluate the ossification timing of fetal sacral vertebrae and sacral length.Definite the number of sacral vertebrae observed in normal fetuses at different gestational weeks,and analyze the correlation between the sacral length and gestational weeks,biparietal diameter and femur length.To compare the normal group with the abnormal group(sacral agenesis).Methods:422 women from November 2017 to December 2018 in Shengjing Hospital of China Medical University were selected(normal group 419 cases,3 cases of abnormal group),singleton pregnancies.The gestational weeks were 16 to 35 weeks,the pregnant women were 20 to 35 years old,the last menstruation was clear,the fetal growth indicators were roughly consistent with the gestational weeks of menopause,and the sacrococcygeal structure of the spine was clear.The GE Voluson E8 and E10 ultrasound instruments were used to count the number of sacral vertebral in fetuses at different gestational weeks using lumbosacral joint angular and three-dimensional ultrasound counting sacral vertebral method.and the distance from the S1 vertebra to the end of the last ossification center were measured.Linear correlation analysis was used to analyze the correlation with gestational age,biparietal diameter and femoral length,and P<0.05was statistically significant.The prenatal ultrasonic characteristics of the abnormal group were summarized,the number of sacral vertebrae was counted,the sacral length was measured,which were compared with the normal group at the same gestational week.Result:1.In this study,419 normal fetuses were collected,and 394 cases were included in the statistical study.There were 25 cases of 16 weeks of fetus,only 10 cases of sacral vertebra showed clear,the display rate was 40%,25 cases of 17 weeks of fetus,only 15cases showed clear,the display rate was 60%.S1 and S2 vertebral bodies were visible at16 weeks,and S3 vertebral bodies were visible in all fetuses at 17 weeks.There were individual differences in the ossification time of the sacral vertebrae.The S4 vertebral bodies could be observed at the earliest at 17 weeks,and all were observed at 20 weeks.The S5 vertebral bodies appeared at the earliest at 21 weeks,and the percentage of it gradually increased with the increasing of gestational weeks,and all fetuses could be shown at 31 weeks.2.The sacral length in normal fetus was positively correlated with gestational age,biparietal diameter and femoral length.The R~2 are 0.914?0.897 and0.904(P<0.05).3.In this study,3 cases in the abnormal group were collected,whose sacral length was not within the 95%confidence interval of the normal value.According to the gestational weeks of case 1 and case 2,the S4 vertebral body should be observed at least,but only S1 and S2 vertebral bodies should be shown,and the lumbosacral tail is rigid,and the natural angle of sacrococcygeal cannot be observed.Case 3 was a typical case of sacral agenesis with significantly shortened spine.All sacral vertebrae were not observed.The iliac wings were close to each other,presenting a"shield shape".At the same time,the results of induced labor also showed that the muscles of the lower limbs were thin,the lower limbs were flexed like frogs,and imperforate anus.Conclusion:1.The results of this study indicate that ultrasound can be used to evaluate the development of the sacral vertebra in the fetus,providing a more reliable reference for the diagnosis of sacral agenesis.2.The vertebral bodies of S1 and S2 were visible at16 weeks,S3 at 17 weeks,and S4 at 20 weeks.The individual differences in the ossification timing of S5 vertebral bodies were greater,ranging from 21 weeks to 31weeks.3.The sacral length increased with the increase of fetal gestational age,biparietal diameter and femur length.The sacral length in patients with sacral agenesis was significantly smaller than the normal value at the gestational age.