Morphometric Analysis of Spinal Cord and Its Termination Within the Vertebral Canal: An Observational Study in the Fetuses of Third Trimester Gestational Age

Background & aim The spinal cord is the continuation of the brain from the lower point of the medulla and the terminal portion of the developing neural tube. The spinal cord develops within the bony canal, called the vertebral canal, formed by the union of individual vertebrae in the vertebral column. Initially, the development of the length of the vertebral column and spinal cord are the same but later on undergo alterations. The growth of the vertebral column is faster than that of the spinal cord because the spinal cord appears to terminate early within the vertebral canal. To measure the length of the spinal cord and lowermost point of conus medullaris in the third trimester gestational age fetuses. Material and methods The present cross-section observational study was carried out on 30 fetuses collected from the museum of the Anatomy Department and Obstetrics and Gynecology Department. Before starting the study, permission and approval from the university's ethical committee were received. The dissection of fetuses includes the incision of the skin, removal of superficial and deep muscles, and a laminectomy. The meninges were cut and removed to note the vertebra level of the termination of the spinal cord. The spinal cord was taken out, and the total length of the spinal cord was measured. The fetuses were categorized into three groups determined by their gestational age (the first group was 28-31 weeks, the second group was 32-35 weeks, and the third group was 36-40 weeks). Observation In the present study, 81.8% of male fetuses were in the 36-40 weeks gestational age group, and 52.6 % of female fetuses were in the 32-35 weeks, gestational age group. The mean length of the spinal cords was 14.74±1.45cm, with a range of 10.95 cm to a maximum of 16.60 cm. In the full-term gestational age group, male fetuses had a greater length of spinal cord than female fetuses. Sixteen fetuses had a spinal cord termination at level L2, followed by eight fetuses at the L3 level and six fetuses at the L4 level. Out of 11 male fetuses, eight fetuses had spinal cord termination at the L2 vertebra level, two at the L3 level, and one fetus at the L4 level. In female fetuses, eight had a spinal cord termination at the L2 level, six at the L3 level, and five at the L4 level. Conclusion The spinal cord length and level of conus medullaris depend on the age of the fetuses. In prenatal diagnosis for different spinal cord pathology, these values can be used as reference values in future studies.