From Gastrulation to Malformation: Understanding the Embryology of Split Cord Malformations for Obstetric Practice

Split cord malformation (SCM) is an uncommon congenital anomaly of the spinal cord in which the neural tube is longitudinally divided into two hemicords, separated by a fibrous, cartilaginous, or osseous septum. Historically described as diastematomyelia or diplomyelia, the current unified classification proposed by Pang et.al distinguishes two main subtypes: type I, characterized by two hemicords within separate dural sacs separated by a rigid spur, and type II, in which hemicords share a single dural sac and are separated by a fibrous band. Composite SCM, with multiple non-contiguous lesions, is exceedingly rare. Although SCM is most often recognized in childhood following neurological symptoms or cutaneous stigmata, advances in fetal ultrasonography and magnetic resonance imaging (MRI) now permit prenatal diagnosis. This shift carries significant implications for obstetric counseling, delivery planning, and multidisciplinary coordination of perinatal care. While surgical correction in infancy remains the mainstay of treatment, the increasing ability to detect SCM in utero has prompted discussion of fetal therapy. Unlike open spina bifida, however, SCM is primarily a tethering disorder rather than a defect of neural tube closure, and no evidence currently supports fetal intervention. This review summarizes embryology, classification, epidemiology, clinical features, diagnostic strategies, and management of SCM, with special emphasis on prenatal imaging, obstetric considerations, and future prospects for fetal therapy.