A fetal ultrasound finding defined by flattening of the occiput with pointing of the frontal bones and brachycephaly with an increased cephalic index. It is characterized by keel shaped deformity of forehead with midline ridge, bilateral fronto temporal constriction with compensatory biparietal expansion, supra orbital and lateral orbital retrusion and hypotelorism. This finding is said to resemble a strawberry.
Comment:
Fetal trigonocephaly can be seen in trisomy 18 (or other chromosomal abnormalities) and monogenic syndromes, particularly also in craniosynostosis syndromes and some skeletal dysplasias.