Megacystis in the First Trimester as an Unreported Sonographic Finding of Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins Confirmed by Whole-exome Sequencing

A pregnant woman was revealed to have fetal univentricular heart and megacystis by a routine first-trimester ultrasound. Chorionic villus sampling with the use of karyotyping and microarray found no causative etiologies. A further investigation with whole-exome sequencing (WES) demonstrated a FOXF1 variant. Autopsy confirmed the prenatal findings, and a histological study of the lungs showed the characteristic features of alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV). This study indicates that although ultrasound itself has no ability of the identification of pulmonary histological malformations associated with ACDMPV, the early markers of univentricular heart and megacystis might alert clinicians to consider this genetic disorder which is facilitated considerably by the increasingly used WES in prenatal diagnosis.