First-trimester three-dimensional ultrasonographic findings in a fetus with frontonasal malformation.

A case of a frontonasal malformation observed during the first trimester with three-dimensional ultrasonography and fetoscopy is reported. Absence of the nasal bone and a poorly characterized nose were visualized at 11 5/7 weeks by two-dimensional ultrasonography. Rendered three-dimensional ultrasound images revealed absence of the nasal bridge, widely spaced frontal bones and hypertelorism. Fetoscopy, performed at 12 3/7 weeks, confirmed the hypertelorism and showed a broad translucent nose with a flat nasal bridge. The final diagnosis of frontonasal malformation was made at autopsy after pregnancy termination. A review of prenatally diagnosed cases as well as the various syndromes having frontonasal malformation as a common denominator is presented.