Screening for fetal spina bifida by ultrasound examination in the first trimester of pregnancy using fetal biparietal diameter

American Journal of Obstetrics and Gynecology, 05/25/2012

Simple and reproducible BPD at 11–14 weeks of gestation could detect half the cases of open fetal spina bifida by identifying 5% of pregnancies for expert scanning in first and second trimester examinations of the fetal spine and cranium.


  • 34,951 unselected consecutive pregnancies included 18 with spina bifida.
  • Another 28 cases were referred for assessment.
  • Biometric measurements were expressed in multiples of the median for crown–rump length.


  • Biparietal diameter (BPD) was smaller in spina bifida (P<0.0001).
  • 22/44 (50%) cases with spina bifida aperta had a BPD < 5th centile.
  • BPD was independent of maternal adiposity and smoking status.

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