Prenatal assessment of fetal vertebrae and ribs by three-dimensional ultrasound and the association with fetal and neonatal outcome.

Introduction: The presence of an abnormal vertebral pattern and (rudimentary) cervical ribs in particular, has been associated with adverse fetal and neonatal outcomes, such as intrauterine fetal death and structural or chromosomal abnormalities. The feasibility and potential added value of prenatal assessment of the vertebral pattern and the presence of cervical ribs is currently unclear. Aims of this study were to evaluate the feasibility of prenatal assessment of the fetal vertebral pattern and cervical ribs using three-dimensional ultrasound and determine whether an abnormal vertebral pattern is associated with adverse fetal and neonatal outcome.

Methods: 1138 Women referred for an advanced ultrasound examination were included and volume data sets of the spine were acquired. The vertebral pattern was reassessed on postnatal radiographic examinations, when available. Associations between adverse outcomes and abnormalities of the vertebral pattern that had at least a good agreement between prenatal and postnatal assessments were studied.

Results: Agreement between prenatal and postnatal assessment of the presence of cervical ribs was poor, which also applied to assessment of the complete vertebral pattern. Moderate to fair agreement existed between prenatal and postnatal assessments of thoracic rib number. Prenatal and postnatal assessments of lumbar ribs had a very good agreement. Lumbar ribs were rare (10/768, 1.3%) and associated with female gender, but not with any other variable.

Conclusion: Lumbar ribs could be assessed very well on prenatal three-dimensional ultrasound and were not associated with adverse outcomes. Prenatal and postnatal agreement between the presence of cervical ribs, number of thoracic ribs and the vertebral pattern was insufficient.