Prenatal US evaluation of the spinal cord using high-frequency linear transducers.

We illustrate the contribution of high-frequency linear abdominal transducers in the prenatal US examination of the spinal cord. After birth, such transducers are commonly used in US examination of the spinal cord. During the third trimester of gestation, the fetal spine is commonly facing anteriorly and US images of the spinal cord can be acquired using a high-frequency linear abdominal transducer. Images of the normal spinal cord, normal variants (ventriculus terminalis, cyst of filum terminale) and spinal cord abnormalities (myelomeningocele, meningocele, diastematomyelia, tethered spinal cord and caudal regression syndrome) are presented. In this pictorial essay, comparison between images acquired with low- and high-frequency transducers are provided as well as correlation with postnatal data. In the normal spine, anatomical details such as the conus medullaris, the filum terminale and the nerve root bundles are exquisitely depicted, making it possible to differentiate normal variants from abnormalities. In abnormal cases, the position of the conus medullaris, its shape and the nerve roots can be analyzed in detail. We describe the benefits of using high-frequency linear transducers in US examination of the spinal cord, which is common after birth but has not been hitherto reported in fetuses.