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

Split cord malformation (SCM) is an uncommon congenital anomaly in which the spinal cord is longitudinally divided into two hemicords separated by a fibrous, cartilaginous, or osseous septum. Historically described as diastematomyelia or diplomyelia, the unified classification proposed by Pang et al. [Neurosurgery. 1992;31(3):451-80] distinguishes two main subtypes: type I, characterized by two hemicords within separate dural sacs divided by a rigid spur, and type II, in which hemicords share a single dural sac separated by a fibrous band. Composite SCM, involving multiple noncontiguous lesions, is exceedingly rare.

Although SCM is most often recognized in childhood following neurological symptoms or cutaneous stigmata, advances in fetal ultrasonography and MRI now permit prenatal diagnosis. This shift carries significant implications for obstetric counseling, delivery planning, and multidisciplinary perinatal care. While surgical correction in infancy remains the mainstay of treatment, the growing ability to detect SCM in utero has prompted discussion of fetal therapy. Unlike open spina bifida, SCM is primarily a tethering disorder rather than a neural tube closure defect, and no evidence currently supports fetal intervention. This review covers the embryology, classification, epidemiology, clinical features, diagnostics, and management of SCM, with emphasis on prenatal imaging, obstetric considerations, and future prospects for fetal therapy.

SCM encompasses distinct subtypes defined by dural anatomy and septum composition. Prenatal imaging has transformed antenatal detection, reshaping obstetric and multidisciplinary planning. As a tethering disorder rather than a neural tube defect, SCM does not currently warrant fetal intervention, and postnatal surgical untethering remains the standard of care.