An optimized approach for early detection of orofacial clefting – recent data on validity of maxillary gap vs. retronasal triangle view

To elaborate the validity and reproducibility of recent markers of orofacial clefting assessed in early pregnancy.

This was a retrospective study reviewing stored 3D volume data sets of first and early second trimester fetuses with suspected or proven genetical and structural abnormalities (n = 135; 73 viable vs. 62 non-viable fetuses). Following volume adjustment, visualization and arrangement of craniofacial anatomy were examined in terms of feasibility of reconstruction of the retronasal triangle view (RNTV) in the coronal plane, and concomitantly assessment of the maxillary ridge in the corresponding midsagittal view, in order to rule out the presence of orofacial clefts.

A total of 121/135 volumes were eligible for final analysis. Mean gestational age was 13 + 3 weeks for viable and 11 + 3 for non-viable fetuses (range 8 + 6 to 17 + 6 weeks). There was no difference in maternal characteristics in both groups. In 79/121 cases (65%) fetal karyotyping was prompted, showing abnormal chromosomes in 43 cases (38 viable vs. 5 non-viable; p < 0.001). Focusing on abnormal maxilla-mandible complex we found irregular RNTV in 38 cases (24/14; p < 0.05), out of which 22 were suspective of orofacial clefting (11/11). In these cases only 12 had an interrupted maxillary echo. In contrast, none of the additional 20 cases (13/7) with maxillary gap had an abnormal RNTV in the coronal plane. A markedly shortened maxilla was noticed in another 8 cases without derangement of RNTV. Of 19 fetuses (13/6) presenting an absent mandibular gap (highly suspective of micrognathia) six (4/2) also had a maxillary gap.

3D multiplanar assessment of abnormal fetuses allows to assess craniofacial integrity by combining image information obtained from coronal (RNTV) and sagittal (longitudinal maxilla) planes both essential for prenatal work-up for the presence of orofacial clefting. While RNTV seems to be the more reliable marker, adjunctive assessment of the maxilla might be of additional value.