Related Experiment Video
Updated: Nov 18, 2025
Author Spotlight: Enhancing Success of Ultrasound-Guided Neuraxial Anesthesia in Cases with Difficult Anatomy
Published on: January 31, 2025
Screening for Open Spina Bifida in a Routine Clinical Setting at the First-Trimester Scan: A Prospective Multicentre
Johanna Tiechl1, Samira Abdel Azim2, Katharina Leitner1
1Department of Obstetrics and Gynaecology, Medical University of Innsbruck, Innsbruck, Austria.
Objective:
The aim of this study was to investigate the performance of screening for open spina bifida (OSB) integrated into the routine first-trimester screening.
Method:
This is a prospective multicentre study of 4,755 women undergoing first-trimester ultrasound scans over a 4-year period. Measurements of the brainstem (BS) diameter and brainstem-to-occipital-bone (BSOB) distance were performed. The cisterna magna (CM) was measured in the tilted axial view.
Results:
Pregnancy outcome data were available for 4,658 fetuses included in this study. There were 5 fetuses with OSB, and in all of them, the BS/BSOB ratio and the CM measurements were abnormal. The sensitivity and specificity of a BS/BSOB ratio >1 were 100%. The sensitivity of a CM width <5th centile was 100%, and the specificity was 95.1%. In 4.6% of cases, the BS/BSOB ratio was between the 95th percentile and 1. In 87.1% of these cases, the CM was normal, and 12.9% had a CM below the 5th percentile.
Conclusion:
Screening for OSB is feasible in routine first-trimester scans. The BS/BSOB ratio shows a very good sensitivity and specificity. In cases with near-normal values for the BS/BSOB ratio, the CM width might be helpful for further assessment.
