Sonographic assessment of the fetal facial blood circulation in first trimester pregnancy: “face on fire and labial rectangle signs”

INTRODUCTION: To describe the anatomical features of the fetal facial blood circulation during the first trimester of pregnancy. METHODS: Blood flow circulation of the fetal face was assessed a prospective cohort of fetuses during routine sonographic screening at 11+0 to 13+6 weeks+days of gestation in a single Fetal Medicine Center in Colombia. In a coronal view of the fetal face, the orofacial circulation was assessed using Micro Vascular Flow mode (MV-Flow™). RESULTS: 162 fetuses with no structural abnormalities were evaluated at a mean gestational age of 12+6 weeks+days. Eight pairs of orofacial arteries could be identified in all cases showing the "face on fire" sign, which includes the supratrochlear, supraorbital, temporal, angular, dorsal nasal, superior labial, labiomental, and the ascending branches of the facial arteries. The perilabial circulation forming the fetal "labial rectangle" sign was successfully identified in all cases, and was delimited anteriorly by the superior labial arteries, laterally by the ascending branches of the facial arteries and posteriorly by the labiomental arteries. CONCLUSION: Evaluation of orofacial circulation was feasible during first trimester of pregnancy. The utility of facial blood trajectory for early detection of lip and palate defects requires assessment in further studies.