The size of the fetal thoracolumbar spine: a three-dimensional ultrasound study

Objective To evaluate three-dimensional sonographic measurements of the thoracolumbar spine in the 16-37 week fetus. Design Prospective cross-sectional study. Subjects Two hundred and eighty-nine patients between 16 and 37 weeks of gestation were enrolled at the time of their anomaly scan or routine third trimester scan if fetal size was appropriate for gestational age and if no fetal anomalies were apparent. Methods Three-dimensional (3D) volume calculation of the first and fifth lumbar vertebral body the 12th thoracic vertebral body and the whole lumbar spine was performed in the transverse plane of the multiplanar mode while lumbar spine length was determined in the sagittal plane. Results All volumetric measurements were significantly correlated with gestational age and estimated fetal weight. For each examined parameter regression analysis was performed to describe the 'best-fit' equation. Conclusions 3D sonography allows volume calculation of the fetal spine. Our study provides further data relating to volume changes in the developing fetal spine between 16 and 37 weeks of gestation.