Screening for Open Spina Bifida in a Routine Clinical Setting at the First-Trimester Scan: A Prospective Multicentre Cohort Study

Johanna Tiechl; Samira Abdel Azim; Katharina Leitner; Astrid Berger; Irene Mutz-Dehbalaie; Georg Goebel; Matthias Scheier

doi:10.1159/000512487

Screening for Open Spina Bifida in a Routine Clinical Setting at the First-Trimester Scan: A Prospective Multicentre Cohort Study

Fetal Diagn Ther. 2021 Feb 3:1-7. doi: 10.1159/000512487. Online ahead of print.

Authors

Johanna Tiechl¹, Samira Abdel Azim², Katharina Leitner¹, Astrid Berger¹, Irene Mutz-Dehbalaie¹, Georg Goebel³, Matthias Scheier⁴

Affiliations

¹ Department of Obstetrics and Gynaecology, Medical University of Innsbruck, Innsbruck, Austria.
² Department of Obstetrics and Gynaecology, Medical University of Innsbruck, Innsbruck, Austria, samira.abdel-azim@i-med.ac.at.
³ Department of Medical Statistics, Medical University of Innsbruck, Innsbruck, Austria.
⁴ Ambulatorium für Fetalmedizin, Feldkirch, Austria.

PMID: 33535205
DOI: 10.1159/000512487

Abstract

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.

Keywords: 11–13 weeks’ scan; Brainstem/brainstem-to-occipital-bone ratio; Cisterna magna; First-trimester screening; Open spina bifida.