Three-dimensional first-trimester transvaginal diagnosis of alobar holoprosencephaly associated with omphalocele in a 46,XX fetus.

A three-dimensional (3D) transvaginal diagnosis of alobar holoprosencephaly (HPE) with associated omphalocele is reported at 12 weeks, 3 days gestation. Diagnosis of HPE was based on visualization of a single holoprosencephalic cavity with absent falx and basal ganglia and omphalocele by the presence of abdominal wall defect with mid-gut herniation. Chorionic villus sampling showed a normal 46,XX karyotype. 3D volumetric reconstruction allowed a more detailed definition of the anatomic landmarks of the lesion, including visualization of a thin rim of cortical mantel within the prosencephalic cavity, the dysmorphic face with flattened nose, and the abdominal eventration that looked like an abdominal air bag on 3D volumetric reconstruction.