Study of positioning of fetal conus medullaris by detecting atlanto-axial intervertebral space with three-dimensional ultrasound

Objective To determine the normal position of the fetal conus medullaris and assess its clinical significance. Methods A total of 550 singleton pregnant women who were examined by fetal ultrasonography in the Department of Ultrasound at the Second Hospital of Fujian Medical University from June 1,2013 to September 31, 2014 were included. Inclusion criteria were pregnancies with regular menstruation cycle and known last menstrual period, gestational age (GA) confirmed by ultrasonographic examinations, and neonate abnormality excluded by pediatrician after born. Routine obstetric ultrasound examinations were performed to measure the biparietal diameter (BPD), femur length (FL), head circumference (HC) and abdominal circumference (AC). The conus distance (CD) was determined by measuring the distance between the distal end of the conus medullaris and the caudal end of the last vertebra. The average value was calculated for each group according to GA. Fifty normal fetuses were randomly selected for quality control. For inter-observer reliability assessment, the same data were collected and analyzed by two different operators. For intra-observer reliability assessment, the data were collected and analyzed twice by the same operator with an interval of half an hour. Linear regression correlation analysis was performed to analyze the relationship between CD and GA, BPD, FL, HC and AC. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were used to analyze the repeatability of the analysis. Results In 518 (94.2%) of 550 fetuses, the CD was successfully measured. Positively correlations between the conus distance and the gestational age was observed. The CD was (10.0±3.3) mm at >14-≤15 weeks (n=17), (27.7±3.8) mm at >20-≤21 weeks of gestation (n=18), (41.5±2.4) mm at >26-≤27 weeks (n=8), (54.7±3.0) mm at >32-≤33 weeks (n=17), and (71.9±2.7) mm at >41-≤42 weeks (n=6). Linear regression correlations between CD (mm) and FL, AC, HC, BPD and GA were: CD=1.04× FL (mm)-8.71, CD=0.23× AC (mm)-10.11, CD=0.28× HC (mm)-18.10, CD=0.90× BPD (mm)-17.65, CD=2.34× GA (weeks) -20.94 (r=0.990, 0.985, 0.978, 0.974 and 0.973, respectively, all P<0.01). The measurement of the conus distance exhibited good reproducibility between different operators (ICC=0.984, 95%CI: 0.972-0.991) and for the same operator (ICC= 0.992, 95%CI: 0.985-0.995) with the 95% limits of agreement of -1.8 to 3.5 mm and -4.3 to 2.1 mm. Bland-Altman analysis showed that most of the measured values were within 95% confidence interval suggesting good consistency. Conclusions The distance, between the end of the conus medullaris and the end of the last vertebral body under ultrasound scan, is positively correlated with FL and other ultrasonographic indicators, which implies that it could be used as a new index for position of fetal conus medullaris. Key words: Spinal cord; Ultrasonography, prenatal; Sacrum

To establish the normal location of the fetal conus medullaris in China. The study include 828 expectant mothers who have single normal fetus. The fetal gestation ages are from 18 weeks to 40 weeks. We examined on lower spine with 3.5–5.0MHz ultrasound probe to determine the position of conus medullaris. Terminals are related to their correspondingly vertebral level and marked with numeral. The range of normal position and mean position were calculated, and the comparison with positions was made in different gestational weeks. The regular of the raise about the fetal conus medullaris and the relevant factors which may influence the position of the conus medullaris were analyzed. The peak of the raising about the fetal conus medullaris is in the 18 ∼ 21 weeks, afterwards, the fetal conus medullaris rise slowly. The fetal conus medullaris reach the level of L3 at 21 weeks gestation, and L2 to L3 that of 22–28 weeks, and L1 to L2 that of 29–40 weeks. The position of conus medullaris terminal has negative relation with BPD HC AC and FL. With the fetal gestation age increased, the position of fetal conus medullaris is raising. The peak of the raise about the fetal conus medullaris is in the fetal period, particularly before 21 weeks. When the babies were born, the mean position of the conus medullaris approached to the adult level of L2, which is obviously higher than the known level of L3.

Objective To explore the role of Oblique View eXtended (OVIX) method in three-dimensional (3D) ultrasound in positioning the fetal conus medullaris terminal. Methods In this study, 122 normal fetuses and 5 fetuses with spinal bifida at 20th to 30th gestation week from October 2014 to May 2015 in our consultation were included after a system ultrasound examination. The conus medullaris terminal of 3D volume data was collected. OVIX was used to form the coronal section of spine which contained conus medullaris terminal and at least above 5 vertebral bodies and position conus medullaris terminal. The development of nervous system of the normal fetuses was followed up till postnatal 28 days. According to the pathological diagnosis of spinal bifida cases after induced labor, the position of conus medullaris terminal in normal cases and spinal bifida cases was compared. Results The fetal conus medullaris terminal could be located in 120 cases (94.5%, 120/127), while the conus medullaris terminals of 7 normal cases were failed to be located, including due to pregnant obesity in 3 cases and due to fetus position in 4 cases. The conus medullaris terminal was positioned in L3 or above L3 in 115 normal fetuses, below L4 in 5 abnormal fetuses including in L5 in 2 cases, in S1 2 in cases, and in S3 1 in case. OVIX results were consistent with the pathological diagnosis in the 5 abnormal cases. Conclusions OVIX could simultaneously display the osseous marks including 12th rib, T12 and the conus medullaris terminal. The fetal conus medullaris terminal can be exactly positioned by OVIX method, which may provide valuable imaging information for prenatal evaluation of spinal bifida. Key words: Ultrasonography, prenatal; Fetus; Conus medullaris; Spina bifida

Objective To explore the diagnostic value of three-dimensional ultrasonography to fetal limb skeletal dysplasia. Methods From December 2005 to December 2009, the fetus with pregnancy of 14 to 40 weeks after routine ultrasound screening were given two dimensional prenatal ultrasound screening, and we found fetal limb skeletal growth abnormalities retained images, meanwhile we used three-dimensional ultrasound surface imaging mode and transparent imaging mode techniques, the location and types of malformations observed by these two kinds of methods were compared. Results Among the 38 974 cases, 70 cases of abnormalities detected by two-dimensional method, while 78 ones detected by three-dimensional ultrasound method, during postpartum follow-up study, 14 cases of miss diagnosis were found, including 4 cases of polydactylism, 2 cases of polydactyly, 2 cases of toe absence, 4 cases of syndactyly, and 2 cases of abnormal finger posture; while in those with three-dimensional ultrasound method, there were only 6 cases found as miss diagnosis, including polydactylism, polydactyly and syndactyly,2 cases for each. The detectable rate for fetal limb deformities of three-dimensional ultrasound was significantly higher than that of two-dimensional ultrasound method. The methods were mainly used to increase diagnostic accuracy for fetal fingers and toes deformities.Conclusions There is no obvious difference in fetal long bone deformity diagnosis between the methods of two-dimensional and three-dimensional ultrasound, but in the fetal fingers, toes and other details, the results of the three-dimensional ultrasound diagnosis is better than that of two-dimensional one. The three-dimensionul ultrasound diagnosis image is intuitive which provides convenience for communicating with pregnant women. Key words: Real-time three-dimensional uhrasonography; Fetus; The fetal four limbs growth malformations; Diagnosis

Objective To investigate the variation in the position of conus medullaris in Chinese adult population in order to avoid hitting conus during spinal puncture. Methods Eight hundred patients suffering from back pain, aged 18-91 yr, were enrolled in this study. The position of conus medullaris was determined using Siemens 1.5 T magnetic resonance imaging system. According to the method described by Reimann, the vertebral body was used as mark of reference to the level of the end of conus. Results There were 190 patients in whom the position of the end of conus medullaris was lower than L1,2 . The incidence of the position of the end of conus medullaris lower than L1,2 was higher in patients 30-60 or older than in those under 30, and in those over the age of 60 than in those 30-60 (P ＜ 0.05). Conclusion Spinal puncture should be performed cautiously at L2,3. CT or MRI is recommended before operation for the patients to locate the position of conus medullaris and avoid injury to the spinal cord. Key words: Spinal cord; Anatomy; Intraoperative complications

Objective To study the feasibility of visualization of atlanto-axial intervertebral space for the localization of fetal centrums with three-dimensional ultrasound and to explore the relationship of intervertebral space with gestational weeks. Methods A total of 223 cases of normal single pregnancy in the second trimester were enrolled in the study to acquire the 3D volume of fetal spines. The distances between the transverse processes of cervical vertebra were measured in vertical horizontal line. The distance between the first and second cervical vertebra was labeled C1, and then labelled C2, C3, C4, C5 and C6 as follows. Results The successful rate of 3D acquisition of 206 cases was 92.4%.The distance between ICC values of C1-C6 were 0.985, 0.984, 0.971, 0.956, 0.978, 0.923, respectively and the consistency data measuring was well. The atlanto-axial intervertebral space was significantly larger than other intervertebral space (P=0.012) and the mean ratios of C1 to C2-C6 were 1.41, 1.39, 1.37, 1.40, 1.39, respectively, which had no correlation with gestational ages (P=0.877, 0.915, 0.838, 0.859, 0.908, respectively). Conclusions Visualization of the atlanto-axial intervertebral space with three-dimensional ultrasound is a direct and simple method without any consumption, which can help to quickly locate the axial vertebra and other vertebras and conus medullaris. Key words: Ultrasonography, prenatal; Fetal vertebra; Conus medullaris; Fetus

The aim of this study is to compare two different methods in assessment of the position of fetal conus medullaris (CM) and to explore the significance for assessment of CM. This study included both normal fetuses and those with the diagnosis of fetal spinal lesions. The position of fetal CM was performed sonographically using two methods: location of CM in relation to the vertebral body (CM level) and measurement of the conus sacrum (CS) distance. The results showed that intra-observer and interobserver concordance was high for the two methods, both in the normal and abnormal groups. There was significant association between femur length and CS distance (R2 = 0.917) and between gestational age and CS distance (R2 = 0.892). We propose the combined use of CM level location and CS distance measurement for the prenatal diagnosis of fetal spinal lesions for complementary needs.

Ultrasound-Based Analysis of Fetal Conus Medullaris Anomalies: A Comprehensive Study on Prenatal Diagnosis and Postnatal Outcomes.

To investigate the clinical features of the abnormal chromosome karyotypes in twin pregnancies complicated with fetal malformations. Totally 181 twin pregnancies (362 fetuses) in which one or two fetuses had abnormalities diagnosed by ultrasound were referred to the First Affiliated Hospital of Sun Yat-Sen University from January, 2000 to September, 2010. They were divided into different groups according to (1) maternal age: the cases with maternal age ≥ 35 were divided into advanced pregnancy group (105 fetuses), and those with maternal age < 35 were divided into young pregnancy group (203 fetuses); (2) conceived method: those conceived by assisted reproductive technology were divided into assisted reproductive group (81 fetuses), and the natural conception pregnancies were divided into natural conception group (227 fetuses); (3) chorionicity: the monochorionic twin (MCT) pregnancies were divided into MCT group (123 fetuses), and the dichorionic twin (DCT) pregnancies were divided into DCT group (185 fetuses); (4) structural abnormalities: 205 fetuses with structural abnormalities were divided into the abnormal fetal group, and 103 fetuses without structural abnormalities were divided into the normal fetal group. All fetuses were examined by the ultrasound and chromosomes were examined in 308 fetuses. (1) The karyotype of fetuses: among 181 twin pregnancies, 23 cases had chromosomal abnormalities in 1 or 2 fetuses (12.7%, 23/181), and chromosomes were examined in both fetuses in 20 of 23 cases. Twenty-six of 308 fetuses were found with abnormal chromosomes (8.4%, 26/308), and the aneuploid was the most common type of abnormal karyotypes (53.8%, 14/26). Twenty-one of 205 fetuses with malformations were found with abnormal karyotypes (10.2%, 21/205). (2) Seven of 123 fetuses in MCT group were with abnormal karyotypes (5.7%, 7/123), and 19 of 185 fetuses in DCT group were with abnormal karyotypes (10.3%, 19/185). There was no statistical difference of abnormal chromosome incidence between the two groups. There were 14 fetuses with aneuploid in DCT group (7.6%, 14/185); but there was no fetus with aneuploid in MCT group. There was statistical difference between these two groups. In two cases of DCT group, only one fetus with malformation received chromosome examination because another fetus was dead, and the karyotypes were trisomy 21 and trisomy 18 respectively. Both fetuses of the rest 17 cases received chromosome examination, and the chromosomes of both fetuses in each pregnancy were different. Fifteen of 19 fetuses with abnormal chromosomes in DCT group were complicated with structural abnormalities, and 7 fetuses of 4 twin pregnancies in MCT group were with chromosomal abnormalities. (3) The comparison of the abnormal karyotype incidence between the advanced pregnancy group and young pregnancy group: the abnormal karyotype incidence of the advanced pregnancy group was 7.6% (8/105), and that was 8.9% (18/203) in young pregnancy group. There was no statistical difference between the two groups (P > 0.05). Six of 105 fetuses in advanced pregnancy group were aneuploids (5.7%, 6/105), and 8 of 203 fetuses in young pregnancy group were aneuploids (3.9%, 8/203). The aneuploid incidence in advanced pregnancy group was significantly higher than that in young pregnancy group (P < 0.05).(4) The comparison of the abnormal karyotype incidence between the assisted reproductive group and the natural conception group: 11 of 81 fetuses were with the abnormal karyotypes in assisted reproductive group (13.6%, 11/81), and 15 of 227 fetuses were with the abnormal karyotypes in assisted reproductive group (6.6%, 15/227). There was statistical difference between the two groups (P < 0.05). There were 7 fetuses with the aneuploid in assisted reproductive group (8.6%, 7/81) and 7 fetuses with the aneuploid in natural conception group (3.1%, 7/227), which showed no statistical difference (P > 0.05). (5) The comparison of the abnormal karyotype incidence between the abnormal fetal group and normal fetal group: 21 of 205 fetuses in abnormal fetal group were with abnormal karyotypes (10.2%, 21/205), and 5 of 103 fetuses in normal fetal group were with abnormal karyotypes (4.9%, 5/103). There was no statistical difference (P > 0.05). 13 fetuses in abnormal fetal group were with the aneuploid (6.3%, 13/205), and only one fetus in normal fetal group was aneuploid (1.0%, 1/103). There was statistical difference between the two groups (P < 0.05). Aneuploid is the most common abnormal karyotype in twin pregnancy complicated with fetal abnormalities, especially trisomy 21. Aneuploid mainly occurs in only one fetus of DCT, and chromosomal discordance is usually found in DCT. While in MCT, the twin fetuses with the same abnormal karyotype may have different phenotypes. The results suggest that it is necessary to analyze both karyotypes of twins even if only one fetus is complicated with structural abnormalities.

To investigate the karyotypes of amniotic fluid cells and compare the incidence of chromosomal abnormality as well as to evaluate the clinical significance of abnormal karyotypes. A total of 13 648 pregnant women came to Shanghai Jiai Genetics and IVF Institute, Obstetrics and Gynecology Hospital, Fudan University to do amniocentesis from September 1998 to November 2010, and 13 795 amniotic fluid specimens were successfully extracted and cultured, thus 13 795 fetuses received karyotype diagnosis. These fetuses were grouped according to different indications. If maternal age was ≥ 35, the fetuses were grouped into the advanced maternal age group (4065); and if maternal serum screening test revealed high-risk of trisomy 18 or trisomy 21, the fetuses were grouped into the high-risk serum screening group (6462); and those with abnormal signs of ultrasound screening were grouped into the abnormal ultrasound signs group (1539); and if either of the parents was with chromosome abnormalities, the fetus was grouped into the paternal/maternal abnormality group (108); whereas the remainder were grouped in other factors group (1621). The amniotic fluid cells were in-situ cultured on coverslips, harvested by conventional G-banded methods, and then analyzed by two doctors. In order to get rapid diagnosis, some pregnant women whose gestational age ≥ 26 weeks accepted fluorescense in situ hybridization (FISH). FISH was done on 78 uncultured amniotic fluid specimens using probes located at chromosome 13, 18, 21, X, Y. Some parents were required to analyze lymphocyte karyotype to help judging the origin of abnormal karyotype. (1) Classification and composition of abnormal karyotypes in each group: a total of 388 abnormal karyotypes were found among 13 795 fetuses, and the abnormal rate was 2.813% (388/13 795). Of the 388 fetuses, aneuploidy was the most common pattern which was up to 59.8% (232/388); autosomal structural abnormality rate was 24.7% (96/388); mosaicism was 12.4% (48/388). Other uncommon abnormal karyotypes included marker chromosome (5/388, 1.3%), sex chromosomal structural abnormality (4/388, 1.0%) and triploid (3/388, 0.8%). Aneuploidy was the most common in most groups except the paternal/maternal abnormality group. There were four cases of rare aneuploid in the advanced maternal age group, the high-risk serum screening group and the abnormal ultrasound signs group respectively. Every type of abnormality could be found in the abnormal ultrasound signs group, and autosomal structural abnormalities were concentrated in paternal/maternal abnormality group. Mosaicism mainly distributed in the high-risk serum screening group, accounting for 20.0% (29/145) of abnormalities in this group. (2) Abnormal types and the incidence: the most common type was trisomy 21 (138/388, 35.6%), followed by autosomal balanced structural rearrangements (80/388, 20.6%), mosaicism (48/388, 12.4%) and trisomy 18 (44/388, 11.3%). Others included non-balanced autosomal structural rearrangements (16/388, 4.1%), 45, X0 (16/388, 4.1%) and 47, XXY (15/388, 3.9%). (3) Lymphocyte karyotype analysis of the couples: parents of 153 fetuses were analyzed to determine the origin of abnormal karyotype. Fifty-eight familial and 95 de novo abnormalities were found. FISH results were the same with G-banding karyotype, and two of these were trisomy 21. Abnormal karyotype composition is different according to different maternal amniocentisis indications. There is a variety of abnormal karyotypes in the second trimester pregnancy, and the risk of fetal malformation is related with the kind of abnormal karyotype.

To determine the position of the fetal conus medullaris (CM) in relation to vertebral body by using three dimensional ultrasound (3D US) from 20 to 32 gestation weeks. To compare the difference of CM position between normal fetuses and fetuses with spina bifida occulta. Two operators independently positioned CM in relation to vertebral body by using 3D US with VCI mode (Figure) in 30 fetuses. Intra- and inter-observer agreements were assessed. The CM position was evaluated in 102 normal fetuses (normal group) and 11 cases with prenatally diagnosed spina bifida occulta (abnormal group) with 3D US. The intra- and inter-observer agreements of CM positioning by 3D US are good, with the Weighted Kappa value 1.0 and 0.788, respectively. The CM position can be determined in 97 of the 102 cases. Linear relationship between CM position and gestational age is established in normal group. The CM position in relation to vertebral body is higher than L3 in all normal fetuses, whereas that is below L3 in all abnormal cases. Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

This study aimed to assess the fetal conus medullaris (CM) position with three-dimensional (3D) ultrasonography and its use in detecting and diagnosing spina bifida occulta (SBO). We examined 150 normal fetuses (gestational age, 20-38 weeks) and 14 fetuses with SBO. All fetuses underwent prenatal 3D ultrasonography, and the CM position in relation to the vertebral body was evaluated using volume contrast imaging. Intra- and inter-observer agreements were assessed using weighted kappa. The correlation between gestational age and CM level was determined by linear regression analysis. Operators successfully located the CM position in 145 cases. The CM was at L3 or higher in all normal group cases. A linear relationship was noted between gestational age (X) and CM position (Y) (Y = 0.118X + 6.011, R(2) = 0.679, P < 0.001). The weighted kappa values for intra- and inter-observer agreement were 1.0 and 0.788, respectively. The CM was located at L3 in one case and lower than L3 in 13 cases in the SBO group. All values were below the fifth percentile for the normal group. Three-dimensional ultrasonography may accurately determine the CM vertebral level. Prenatal evaluation of the CM position may improve the detection and diagnosis of SBO.

To explore the position change of fetal conus medullaris by ultrasound, and to propose gestational age-specific references for the lower limits of fetal conus medullaris level. We prospectively collected the imaging and clinical data of fetuses whose mothers accepted routine prenatal ultrasonic follow-ups in the Department of Medical Ultrasonics, Chinese PLA General Hospital, between November 2020 and April 2021. By assigning to the conus medullaris levels, calculating statistical data, and performing linear regression analysis, we determined the correlation between the conus medullaris level and gestational week, as well as between the 95th percentile of the conus medullaris level, i.e., the lower limit of the conus medullaris level, and gestational week. We included 1202 different fetuses at 17-40 gestational weeks in the study. Both the conus medullaris level and the 95th percentile of the conus medullaris level were linearly correlated with gestational week. We calculated the adjusted values of the lower limits of fetal conus medullaris levels, that is, the theoretical references of the lower limits, according to the linear regression equation, and composed a comparison table. The fetal conus medullaris position continues changing cranially with gestational weeks during the whole pregnancy. The conus medullaris of a term fetus should not lie below the L2 vertebra level at birth. We proposed reference criteria of fetal low-lying conus medullaris for each gestational week from 17 to 40weeks of gestational age, which potentially help prompt diagnosis and improve prognosis of fetal tethered cord syndrome.

Objective To investigate the clinical value of pulmonary arterial resistance and pulsatility index (RIPA) in the prediction of fetal lung maturity (FLM). Methods 305 fetuses of 37 - 40 weeks pregnancy were selected. According to the foam test of amniotic fluid and Apgar score they were divided into an abnormal group (15 cases) and a normal control group (290 cases). Color Doppler ultrasound was used to detect fetal RIPA in each case. Results The RIPA of the normal fetuses decreased with the increase of gestational age; these two were highly correlated (r=-0.98, P < 0.05). The RIPA of the normal fetuses was (0.82 ± 0.02) and that of the abnormal group (0.86 ± 0.01) (P < 0.05). Conclusions Fetal RIPA in the pregnancy regularly changes. Fetal RIPA change closely relates with fetal lung maturity. Fetal RIPA can effectively and clinically assess fetal lung development. Key words: Pulmonary artery; Fetal lung maturity; Color Doppler ultrasound

Objective To evaluate the development of cerebral sulci and gyrus in fetuses with conotruncal defect(CTD) at the second and third trimester by ultrasound, and to improve clinician′s understanding of the cerebral cortical development in fetuses with CTD. Methods The study was conducted at Shenzhen Maternity and Child Healthcare Hospital Affiliated to Southern Medicial University from December 2015 to January 2017, enrolled 180 women with single fetus, among whom 60 fetuses with CTD and gestational age between 20 weeks to 33+ 6 weeks were diagnosed by echocardiographic examination. CTD included persistent truncus arteriosous, tetralogy of fallot, transpofition of the great arteries and double outlet of right ventricle. Evaluation indexes of cerebral sulci and gyrus included depth and angle of parietooccipital sulcus, width and depth of sylvian fissure, uncovered width of insular, uncovered insular ratio, depth of calcarine sulcus, head circumference; evaluation indexes of hemodynamics included umbilical artery resistance index, umbilical artery pulsation index, middle cerebral artery resistance index, middle cerebral artery pulsation index, the cerebral-to-placental resistance ratio and the cerebroplacental pulsation ratio. Above indexes were measured for statistical analysis. Results At the whole gestational age in the study, depth of parietooccipital sulcus and width of sylvian fissure in CTD fetuses were smaller than those in the control group, uncovered insular ratio was larger than that in the normal group(P<0.05); middle cerebral artery resistance index, middle cerebral artery pulsation index and the cerebroplacental pulsation ratio in CTD fetuses were lower than those of the control group (P<0.05). Conclusions The change of hemodynamics in fetuses with CTD may be one of the reasons that fetuses with CTD have cerebral cortical hypoevolutism. Key words: Ultrasonography, prenatal; Fetus; Conotruncal defects; Sulci and gyrus