Study of recognition of atlanto-axial intervertebral space for the localization of fetal vertebrae with three-dimensional ultrasound

Abstract

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