Study On Prenatal Ultrasound Of Fetal Skeletal Dysplasia

Objective:In recent years,the incidence of of fetal congenital malformations occurred significantly increased,impacted by the role of a variety of factors,such as environmental factors,social pressure,food safety and many other social problems.The incidence of skelet al deformity accounted for about 26%of the total number of deformities[1].With the improvement of the ultrasound physician recognition ability on fetal abnormal ultrasound image analysis,the missed misdiagnosis rate of severe fetal deformity decreased significantly,however,due to anatomical changes too small to be obvious or fetal gestational age,Position,the amount of amniotic fluid and so on,there are still some smaller fetal malformation,which are difficult for prenatal ultrasound to accurately diagnose.It is reporterd that the total detection rate of prenatal ultrasound in musculoskelet al system and limb deformity is low,and the rate of missed diagnosis is high,about 23%-55%[2,3]and 45%-77%[2,4],respectively.Congenital skeletal limb deformities bring children the defects of the appearance and function,affecting seriously the quality of life of children,resulting in heavy stress and burden for children,so the prenatal ultrasound misdiagnosis and misdiagnosis of fetal skeletal limb deformities are the most likely cases of medical disputes.An important method to diagnose limb deformity and avoid misdiagnosis is to do the prenatal ultrasound of the fetus seriously.The main purpose of this study is to analyze the ultrasonographic features of fetal skeletal limb deformity,analyze the causes of missed diagnosis of fetal skeletal limb malformation,and further improve the physician’s ability of understanding and discrimination of fetal limb deformity,improve the diagnosis level of the physician,reduce the missed and misdiagnosis rate of fet al skelet al limb malformation,improve population quality.Method:The biological measurements and system structure screening of the fetus were carried out in accordance with the standards and methods in the Prenatal Ultrasonography Guidelines published in 2012.Using the American Voluson series of color Doppler ultrasound diagnostic system,two-dimensional and three-dimensional probe on the fetus for prenatal ultrasound.1.Ultrasound assessment of whether the level of lethal malformation:observe the shape of the bone and the degree of ossification,measure the head circumference,chest circumference,abdominal circumference and foot length,the ratio of femur and ventral circumference and the ratio of bust and abdomen,femur and foot length ratio,and measured amniotic fluid,left and right lung volume of measurements using three-dimensional ultrasound.Three-dimensional ultrasound measurement of fetal lung volume:volume data were collected on the four-chamber plane in the fetal thoracic cross-section with application of three-dimensional volume probe,in the absence of fetal movement.The image should include only the heart and chest,and the image was magnified 2/3 of the screen.All three-dimensional images were collected by the same observer.Fetal lung volume were measured by VOCAL rotation technique.In the three orthogonal planes obtained,the A plane was selected as the initial plane and rotated around the Z axis.In accordance with the choice of step 30 °,manually depict 6 times,complete 180° rotation,the lung volume map were obtained with the program software automatically.2.The method of ultrasound examination of the fetal limbs:fetal limbs were scanded in accordance with the continuous sequence of tracking method[5]:each limb of the fetus was scanded along the natural stretch and the posture of the limbs,from proximal limbs to distal limbs.The scan of fetal limbs of the side of the body were completed while scanning the other side.Ultrasound examination method of fetal hands:the coronal section of the bilateral palm and fingers wered scanned,from the wrist to the fingers,until the fingertips;and then the horizontal section wered obtained from the distal of ulnar and radius to the wrist,and then to the metacarpal and phalanx until the fingertips,and finally the sagittal plane wered got to scan a single finger long axis.Ultrasound examination method of fet al foot:longitudinal section wered obtained to observe the ankle,foot,toe and the posture of toe and the toe bone and metatarsus,the relationship of the longitudinal of the calf and the plantar plane.Cross section wered obtained from the ankle to and toe and until the toe tip,to observe the fetal foot toe bone and metatarsus with or without abnormalities.Three-dimensional ultrasound method of fet al limbs:when limb abnormalities were suspected on two-dimensional ultrasound,3D Press was activated,using surface imaging mode,skeleton imaging mode,abnormalities can be clearly display in the 3D sampling frame,and then the images were obtained by pressing the set button.A satisfactory three-dimensional image could be get throurgh adjusting the X,Y,Z axis,and then be stored in the workstation.3.The ultrasound examination method of fetal spine:the scanning of the fetal spine mainly include the sagittal section,cross section,coronal section,the dynamic observation include fetal spine,spinal cord and surface soft tissue.Fetal spine abnormalities were found on the conventional two-dimensional ultrasound examination,Three-dimensional ultrasound of fetal spine should be carried out.3D press was activated,using surface imaging mode,skeleton imaging mode,abnormalities can be clearly display in the 3D sampling frame,and then the images were obtained by pressing the set button.A satisfactory three-dimensional image could be get throurgh adjusting the X,Y,Z axis,and then be stored in the workstation.Student’s t-test was used to compare differences between different groups,and data are presented as means ± S.D.SPSS software was used for statistical analyses and P<0.05 was considered to indicate a statistically significant difference.Result:There are 68,008 cases of pregnant women undergoing prenatal ultrasound examination,during 2013.1.1-2016.12.31 in Ultrasound Department of Obstetrics and Gynecology,Renmin Hospital of Wuhan University,including 65703 cases of single fetus and 2305 cases of twins,minssing 1003 cases(single fetus 700 cases +300 cases of twins),a total of 69013 cases of fetuses.There were 7 cases of lethal fet al skelet al dysplasia,and the occurrence rate of lethal skeletal dysplasia is 0.01%.There were 3 cases of thanatophoric dysplasia(TD),2 cases of osteofenesis imperfect(OI)type Ⅱ and 2 cases of achondroplasia(ACH)in 7 cases of lethal skeletal dysplasia.There are 475 cases of limb deformity,the incidence rate is 0.7%.There are only 47 cases of fetus with a single limb deformity,and the rest with two or more limb deformities.There are 142 cases of fetus wih alone limb deformity,the rest combined with other system abnormalities in 219 cases of fetus.Amniocentesis/umbilical cord blood puncture were carried out in 89 cases of fetus for chromosome karyotype examination,and there are 37 cases of fetal with chromosomal abnormalities,52 cases of fetal with normal chromosomes.57 cases of fetal limb deformity were found in first trimester,350 cases in second timester,and 68 cases in the third trimester,the percentage was 12.0%,73.7%and 14.3%respectively.There were 71 cases of fetus with vertebral deformity,and the incidence rate of vertebral deformity is about 1.03 ‰.40 cases of fetus with semi-vertebral,23 cases of fetus with butterfly vertebral,2 cases of fetus with coronal vertebral body,6 cases fetus with vertebral fusion.In this study,ther were 13 cases of butterfly vertebral fetus with semi-vertebral body,2 cases of coronal vertebral body were the same vertebral body with butterfly vertebrae,3 cases of semi-vertebral fetus with rib fusion,2 cases of semi-vertebral fetus with rib defect.In this study,prenatal ultrasound detection rate of limb deformity was 83.9%,missed diagnosis rate 16.1%,misdiagnosis rate 4.3%.5 cases of fetus with Hip dysplasia,missed diagnosis rate was 100%,2 cases fetus with over-adductionand,1 with posture fixed.There were 17 cases of misdiagnosis,35.4%of missed diagnosis rate,3 cases of missed diagnosis of knee joint,33.3%of missed diagnosis rate,2 cases of over-adduction,over-adduction Outreach 1 case.Foot diarrhea diagnosis of 25 cases of fetusl,missed diagnosis rate of 13.8%.Conclusion:1.There are both lethal and non-lethal types of skeletal dysplasias.Many of the disorders can now be diagnosed prenatally by ultrasonography,many skeletal limb dysplasia,especially more serious skeletal limb dysplasia,can be diagnosed,which can effectively prevent the birth of abnormal fetuses,reduce birth defects,bringing significance for the implementation of eugenics.With the development of ultrasound technology,three-dimensional ultrasound in the screening and diagnosis of skeletal limb deformity plays an important role.The application of two-dimensional ultrasound combined with three-dimensional ultrasound can increase detection rate of skelet al limb dysplasia.2.The skeletal dysplasias are developmental disorders of the bones and encompass a large number of conditions most of which are genetic in origin.Over 400 developmental disorders of the skeletal system have been described,many with several subtypes further increasing the number of entities.The detection rate of prenatal ultrsound diagonse is difference between the largerand hand/foot deformity.The deformity of hand/foot is most easily missed,especially refers to the fi ngers/toe abnormalities,including the number of finger/toe and so on.the missed diagnosis rate of the changes of the joints and function,especially the hip and knee,are very high,which remind the ultrasound physician in the future work should pay attention to scanning.It is easy to observe the joint shape in the first trimester,because the fetus is relatively small,and the upper/lower limbs can be displayed in the same screen.3.Diagnosis of prenatal-onset skeletal dysplasias can be accomplished by ultrasound evaluation and confirmed by both molecular testing using invasive procedures and postdelivery radiographs and autopsy,including histomorphic analysis of cartilage and bone.Obtaining a precise diagnosis by prenatal ultrasound diagnosis can be challenging.These diagnoses based on the constellation of findings can be used for counseling regarding optimal patient management and calculation of recurrence risk.4.Three trimesters ultrasound evaluation of the fetus for detection of congenital skeletal dysplasias and the time point are very important.the first ultrasound evaluation,first trimester ultrasound evaluation(11-13+6week),the main purpose is to exclude severe skeletal dysplasias;the second trimester ultrasound evaluation(20-24week)of the fetus for detection of congenital anomalies,most of the skeletal limb deformities can be found;the third trimester ultrasound evaluation(28-32week)is supplemental examination of limb deformities.Fetal structure deformity is a dynarmic process of change,we should do best evry prenatal ultrasound evaluation in order to improve the detection rate of skeletal deformity,reduce missed misdiagnosis,reduce the birth rate of severe limb deformities,improve population quality.