Prenatal Diagnosis of Alobar Holoprosencephaly Facilitated by the Combined Use of Ultrasound and Magnetic Resonance Imaging

Abstract

Objective: Alobar holoprosencephaly is the most severe form of holoprosencephaly. The poor prognosis of fetuses with alobar holoprosencephaly makes early diagnosis in utero important. Herein we report on a case of alobar holoprosencephaly diagnosed in the second trimester using both ultrasound (US) and magnetic resonance imaging (MRI). Case Report(s): A pregnant 25-year-old woman underwent an abdominal US examination at 19 weeks 3 days. A detailed US examination using a 3.5-MHz transabdominal probe demonstrated a fused single ventricle, a fused thalami, a cleft lip and palate, and the absence of falx cerebri in her fetus. T2-weighted MRI further revealed the fetal body with all brain cavities outlined by segmentation. After amniocentesis and prenatal counseling, the couple chose to terminate the pregnancy. The fetus was aborted using vaginal prostaglandin. Fetal karyotype showed 46, XY. Histological examination revealed alobar holoprosencephaly with cleft lip and palate. Conclusion(s): MRI does not alter the diagnosis of alobar holoprosencephaly made solely by obstetric US, but it may provide improved visualization of fetal alobar holoprosencephaly.