Premaxillary protrusion assessment by the maxilla-nasion-mandible angle in fetuses with facial clefts

Objective: The aim of the study was to measure the degree of premaxillary protrusion in fetuses with orofacial clefts of various severities. Methods: The maxilla-nasion-mandible (MNM) angle was measured retrospectively on by multiplanar corrected volumes. Sixty-two fetuses with orofacial clefts and known outcome volumes of the fetal head were available. Results: In 48 of the 62 cases, the MNM angle could be measured [mean gestational age 23 (range, 18-30)weeks]. The mean MNM angle was normal in all nine cases with cleft lip and intact alveolar ridge (15.2°; range, 12.5°-16.9°). In 24 cases with unilateral cleft lip with or without cleft palate (UCL/P), the mean MNM angle was 20.0° (range, 13.3-26.2°), being above the 95th percentile in 79% (n=19) and normal in 21% (n=5). In 14 bilateral cleft lip and palate (BCL/P) cases, the mean MNM angle was 26.5° (range, 19.2°-33.7°) and above the 95th percentile in all cases. There was no difference in MNM angle between isolated clefts and clefts associated with other anomalies. In one case with a Tessier 4 cleft, the MNM angle was above the 95th percentile (25.2°). Conclusion: The premaxilla tends to protrude in both BCL/P as UCL/P cases. The degree of protrusion varies greatly, especially in the BCL/P group.