Abstract:
The objective of this project was to determine whether, in the second and third trimesters of pregnancy, the prefrontal space ratio, the frontomaxillary facial angle, the prefrontal space, the distance between corpus callosum and the mandibulomaxillary axis, as well as the mandibulo-fronto-nasal axis can be helpful in screening for open spinal defects by ultrasound.
These parameters were measured in 71 spina bifida fetuses in the second and third trimester of pregnancy according to standardised protocols. The normal values for the PFSR were previously published by our group and were derived from 279 normal control cases. To determine the normal values for the FMF angle, PFS, CCM and MNF in the second and third trimesters of pregnancy we used the same stored images from the above-mentioned study.
In fetuses with spina bifida, the frontomaxillary angle was significantly smaller than in the normal population. However, only in about a fifth of the affected fetuses, the measurement was below the 5th centile. The PFSR, PFS, CCM and MFN were similar in both groups.
Thus, the frontomaxillary angle is smaller in second and third trimester fetuses with open spina bifida than in controls, however the difference is not pronounced enough to implement this marker in current screening programs.