Neural tube defects (NTDs) occur during embryogenesis, specifically during the fifth or sixth week of gestation, and are described as aberrant neural tube closing. The defect may alter the normal development of the vertebrae, spinal cord, cranium, or brain. The present study describes the case of a 41-year-old pregnant woman with fetal sacral meningocele, no associated pathologies, no family history of neural tube defects, a pregnancy under folate supplementation with the aim of highlighting the importance of ultrasound in diagnosing neural tube defects. The ultrasonographic diagnosis was not clear from the beginning. In our case, the differential diagnosis of meningocele was made with the cystic compound of a sacrococcygeal teratoma, which represents one of the most common congenital tumors in newborns. The particularity of this case was that a neural tube defect occurred despite the prophylactic administration of folic acid during pregnancy, which represents a well-documented protection against neural tube defects in fetuses.