Background   Accurate prenatal diagnosis of fetal spinal neural tube defects is relatively difficult but is of great clinical significance.

  Objective   To explore the detection rates, advantages and disadvantages of prenatal ultrasound and fetal MRI in the prenatal diagnosis of spinal neural tube defects.

  Methods   From August 2018 to August 2020, fetal cases suspected of spinal neural tube defects admitted to the department of neurosurgery of the First Medical Center of Chinese PLA General Hospital were enrolled in this study. All the cases were followed up, and further fetal magnetic resonance imaging (MRI) was performed within 72 hours after the ultrasound diagnosis. Then MRI was performed within 1 month after birth. The detection rates of prenatal ultrasound and fetal MRI were analyzed based on the post-birth MRI as the gold standard, and the detection rates of both methods in the diagnosis of spinal neural tube deformity were evaluated.

  Results   Totally 35 fetal cases were included in this study. During the follow-up, 29 cases chose to continue pregnancy, and 6 cases chose to terminate pregnancy. At the end of the follow-up, 24 fetuses were born, and 5 cases were still in pregnancy. After birth, MRI showed spina bifida in 17 fetuses, lipomatous spinal cord in 12 fetuses, and simple spinal cord in 6 fetuses. The detection rates of prenatal ultrasound versus fetal MRI for spina bifida (64.7% 11/17 vs 41.1% 7/17), for lipomatous tethered cord (58.3% 7/12 vs 75% 9/12), for simple tethered cord (66.7% 4/6 vs 83.3% 5/6) were different, but the differences were not statistically significant (all P＞0.05).

  Conclusion   Prenatal ultrasound has advantages over fetal MRI in the prenatal diagnosis of spina bifida, while fetal MRI has advantages over prenatal ultrasound in the prenatal diagnosis of lipomatous tethered cord; the two methods have a similar performance in the prenatal diagnosis of simple tethered cord.