RecruitingDevice studyFetal Endoscopic Tracheal Occlusion (FETO) for Severe Congenital Diaphragmatic HerniaThe purpose of the study is to study the efficacy of fetal endoscopic tracheal occlusion (FETO) in cases of severe congenital diaphragmatic hernia (CDH). This study will also collect safety and effectiveness data for the off-label use of the FETO Goldballoon (the balloon that will be inserted into the fetal trachea), manufactured by Balt medical. The investigators hope to study the risks and benefits of FETO in cases of severe CDH in an advanced medical center such as Lucile Packard Children's Hospital (LPCH) Stanford with access to advanced maternal-fetal medicine, neonatal services, and neonatal ECMO, and pediatric surgery.