Fetal lumbar spine volumetry by three-dimensional ultrasound

Objectives To evaluate three-dimensional sonographic volume measurements of the thoracolumbar spine from 16 to 25 weeks of gestation in the normally developing fetus. Design Prospective cross-sectional study. Subjects The study included 103 women between 16 and 25 weeks of gestation. They were enrolled at the time of their anomaly scan. None of the pregnancies was associated with structural anomalies and in each case fetal size was deemed appropriate for gestational age. Methods Three-dimensional volume calculation of the 1st and 5th lumbar vertebral body, the 12th thoracic vertebral body and the whole lumbar spine was performed, using the perpendicular frontal, sagittal and transverse planes. The lumbar spine length was determined. Results A statistically significant increase in all measurements was found with advancing gestational age. Conclusions Three-dimensional ultrasonography allows volume calculation of the fetal spine. Our study provides preliminary data about volume changes in the developing fetal spine between 16 and 25 weeks' gestation.