Ultrasound prenatal diagnosis of a lateral facial cleft (Tessier number 7).

Lateral facial clefting may occur as an isolated phenomenon or in association with other disorders. It may originate from a failed penetration of ectomesenchyme between the developing maxillary and mandibular prominences, but disruptive factors may also occur in a proportion of cases. The frequency of this abnormality is estimated as 1 in 50 000-175 000 live births. We describe a case of isolated symmetrical lateral facial cleft (number 7 according to the Tessier classification) diagnosed prenatally on ultrasound examination at 26 weeks of gestation.