Evolution of prenatal detection of neural tube defects in the pregnant population of the city of Barcelona from 1992 to 2006

Objectives: To assess the prenatal ultrasound detection rates (DR) of neural tube defects (NTDs) and its evolution over the 1992 to 2006 period in the pregnant population of the city of Barcelona.

Methods: Data on the population-based register of birth defects were used to assess the evolution of the prenatal DR for isolated NTD, including anencephaly, spina bifida and encephalocele by trimester of gestation.

Results: In the register, 127 isolated NTD cases, including 71 anencephalic fetuses, 49 spina bifidas and 7 encephaloceles were noted. Overall, prenatal ultrasound DR for isolated NTD was 94%. All fetuses with anencephaly or encephalocele were prenatally detected (100% DR), whereas DR for spina bifida was 84%, with no apparent variation over the observation period. An important increase in first trimester DRs was observed for anencephaly, rising from 16% in the first years of the study (1992-1996) to 71% in the last years (2002-2006).

Conclusion: A high DR (94%) for isolated NTD was observed in the city of Barcelona. The single significant change across the study period was an increase in the first trimester DR for anencephaly (from 16% to 71%).