Objective:

To evaluate cranial ultrasound markers in routine screening scan for open spina bifida (OSB) between 11 and 13+6 weeks of gestation.

Methods:

This was a retrospective study including 6 cases of spina bifida ［three cases were OSB and the others were closed spina bifida (CSB)］ and 30 controls in Obstetrics and Gynecology Hospital of Fudan University between June 2020 and December 2021. Indirect cranial markers of OSB were evaluat

ed on stored ultrasound images and the medical records were reviewed. Four lines view (4LV) and maxillo-occipital (MO) line were assessed on the sagittal view

whereas the ratio of mean choroid plexus length and occipitofrontal diameter (R-CP) were measured on the axial plane. All cases of spina bifida or controls diagnosed prenatally were confirmed at birth or by autopsy.

Results:

The 4LV sign and the junction between the midbrain and the brain stem above the MO line on the sagittal view were found

and R-CP on the axial plane were between 0.43-0.55 in 3 CSB fetus and 30 controls. 3LV and the junction between the midbrain and the brain stem below the MO line were seen and the R-CP were 0.62

0.68 and 0.67 in OSB fetus

which were significantly higher than the other groups (

P

＜0.001).

Conclusion:

The 4LV and MO line on the sagittal view and R-CP on the axial plane appear to be the effective indirect cranial sonographic markers of OSB and can be easily obtained during the routine first-trimester scan.