Neural tube defects and associated anomalies in South Carolina.

Background: Neural tube defects (NTDs) occur as isolated malformations and in the company of other birth defects. This study was conducted to determine the frequency of coexisting anomalies and the relationship between them.

Methods: Since 1992, NTDs have been identified through prenatal and postnatal surveillance activities in South Carolina. The type of NTD and presence of associated anomalies were determined by prenatal ultrasound, postnatal and/or postmortem examination.

Results: During the ten-year period from 1992 to 2002, 564 NTDs were identified by the surveillance system. Seventeen percent of NTDs (98/564) had associated malformations. In approximately half (n = 51) of these cases, the NTDs and associated anomalies were components of a recognizable syndrome. In the remaining cases (n = 47), no syndrome was identified or suspected, but the associated anomalies were believed in most instances to be secondary to space limitation or neural crest abnormalities imposed by the NTD.

Conclusion: Seventeen percent of NTDs in South Carolina have associated malformations. In most cases, the associated anomalies are considered either components of a multiple malformation syndrome or secondary to the NTD.