Improved sonographic visualization of the fetal spine with the mother seated

Evaluation of the fetal spine is an essential part of obstetric sonography; however, many technical factors may limit this examination. The purpose of our study was to determine if having the mother seated during sonography could significantly improve visualization of the fetal spine when sonography in routine supine and decubitus positions had failed.

A prospective study was performed on 526 consecutive fetal spines of obstetric patients. The estimated gestational age of the fetuses was 16 weeks or more. Sonography of the spine was considered satisfactory if the spine was seen in its entirety in the posterior sagittal and axial projections. If the spine was not entirely seen, a short (< 3 min) sonogram was obtained with the mother seated to see the remaining spinal segments. Sonograms were assessed for improved visualization of the spine and whether the entire spine could be seen on the routine and seated studies. Hard-copy images of the sonograms were also analyzed independently by two radiologists. Intraobserver agreement (in the prospective and retrospective analyses) and interobserver agreement of the reviewers (in the retrospective analysis) were assessed using Cohen's kappa coefficient.

Of the 526 fetal spines initially insonated in the supine or decubitus position, 68 spines (13%) were not satisfactorily seen and required the seated technique. This technique improved the sonographic visualization of the spine in 43 (63%) of 68 cases. The seated technique allowed the previously nonvisualized spinal segments to be completely seen in 37 cases (54%). However, in six cases (9%), improved visualization of the fetal spine fell short of complete visualization. Retrospective analysis showed a high degree of interobserver and intraobserver agreement, with kappa values of .97 and .94, respectively.

Sonography performed with the seated technique is simple and can significantly improve visualization of the fetal spine when the spine is not satisfactorily seen in routine supine or decubitus positions.