RESUMO
Objective To evaluate the value of three-dimensional ultrasound volume contrast imaging (VCI) and tomo graphy ultrasound imaging (TUI) techniques in observing fetal spinal conus medullaris (CM) position and lumbar enlargement of spinal cord morphologic changes,for assessment of tethered cord (TC).Methods Totally 17 abnormal fetuses of spinal diseases combined with TC (abnormal group) were examined by three dimensional ultrasound VCI and TUI techniques.The position of CM was recorded,and the transverse and anteroposterior diameters of lumbar enlargement of spinal cord were measured and compared with 300 cases of normal fetuses (normal group).Results As the growth of the gestational age (CA),CM terminal position increased.All the ends of CM located at L3 or L3 above level in normal.The transverse and anteroposterior diameters of lumbar enlargement in normal group showed good linear relationship with GA.Transverse diameter (mm) =0.677+0.147 ×GA (R2 =0.836,P＜0.05),anteroposterior diameter (mm)-0.994+ 0.152× GA (R2=0.894,P＜0.05).Compared with the corresponding GA fetuses in normal group,the anteroposterior diameter of lumbar enlargement decreased in abnormal group (P=0.002),while no statistical difference of the transverse diameter was found between the two groups (P=0.082).Conclusion Position of CM and lumbar enlargement measure ment can provide valuable reference information for clinical prenatal diagnosis of fetal spinal TC.