Holoprosencephaly at 9 weeks 6 days in a triploid fetus: 2D and 3D ultrasound findings

OBJECTIVES
To report one of the earliest prenatally diagnosed cases of holoprosencephaly, in which 3D imaging was used to assist in the diagnosis.

CASE REPORTA
transvaginal scan was performed at 9 weeks 6 days because of a suspected fetal anomaly detected at the booking scan. 2D and multiplanar 3D views revealed a singleton fetus with a crown-rump length of 34 mm. An anechoic area was clearly identified in the anterior aspect of the fetal brain, suggesting the diagnosis of alobar holoprosencephaly. A chorionic villus sampling was carried out one week later, at which time the pre-procedure abdominal scan revealed a single cerebral monoventricular cavity, fused thalami, midfacial hypoplasia, absent orbits, small omphalocele and an increased nuchal translucency thickness of 5.6 mm. The placenta appeared normal and the fetal growth interval was within normal range. Trophoblast culture revealed a 69,XXY karyotype. The patient miscarried at 13 weeks.

CONCLUSIONS
The prenatal detection of holoprosencephaly before 10 weeks can be considered as an early manifestation of fetal triploidy,despite normal placental appearance and adequate growth interval. 3D ultrasound can assist in the first-trimester diagnosis byproviding multiplanar views of the fetal head and face.