Agnathia-otocephaly or agnathia-sinotia-microstomy syndrome is the most severe malformation affecting the first branchial arch. It is a rare congenital anomaly characterized by absence of the lower jaw and abnormal ear positioning. Prenatal diagnosis is possible on conventional 2-D ultrasound in the second trimester. Three-dimensional ultrasound enhances detection of abnormal facial phenotype, especially in surface rendering mode. In addition, 3-D volume datasets are used to produce a physical model of the anomaly. We present a case of second trimester ultrasound diagnosis of agnathia-otocephaly associated with limb deformities. A physical model produced using 3-D ultrasound volume datasets facilitated better understanding of this congenital malformation, and improvement of parental counselling and management by the multispecialist team.

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