Safety and Efficacy of Fetoscopic Endoluminal Tracheal Occlusion in Congenital Diaphragmatic Hernia

Inclusion Criteria:

• Pregnant person age 18 years or older

• Singleton pregnancy

• Normal fetal karyotype with confirmation by culture results, Chromosomal Microarray (CMA) with non-pathological variants, Whole Exome Sequencing (WES) or Whole GenomeSequencing (WGS). Results by florescence in situ hybridization (FISH) will beacceptable if the patient is >26 weeks gestation

• Gestational age at enrollment less than 29 weeks 6 days

• Intrathoracic liver herniation

• Isolated left Congenital Diaphragmatic Hernia (CDH) with Lung to Head CircumferenceRatio (LHR) <30% at enrollment OR isolated right CDH with LHR <= 45% at enrollment

• Cervical length by transvaginal ultrasound >= 20 mm within 24 hours of FETOprocedure

• Psychosocial criteria

• Able to provide informed consent

Exclusion Criteria:

• Patient < 18 years of age

• Multi-fetal pregnancy

• History of natural rubber latex allergy

• Preterm labor, cervix shortened (<20 mm at enrollment or within 24 hours of FETOballoon insertion procedure) or uterine anomaly strongly predisposing to pretermlabor or placenta previa

• Psychosocial ineligibility precluding consent

• Inability to reside within 30 minutes of OHSU

• Inability to comply with the travel for the follow-up requirements of the trial

• Lack of a support person (e.g., spouse, partner, mother) available to stay with thepatient for the duration of the pregnancy at OHSU.

• Bilateral CDH, isolated left sided CDL with LHR >= 30% or isolated right side CDHwith LHR >45% as determined by ultrasound

• No intrathoracic liver herniation

• Additional fetal anomaly and chromosomal abnormalities, associated anomaliesrecognized to alter survival prognosis (i.e. congenital heart disease) or presenceof an underlying genetic syndrome (i.e. Fryns) by ultrasound, MRI, or echocardiogramat the fetal treatment center

• Maternal contraindication to fetoscopic surgery or severe maternal medical conditionin pregnancy

• History of incompetent cervix with or without cerclage

• Placental abnormalities (previa, abruption, accreta) known at time of enrollment

• Maternal-fetal Rh isoimmunization, Kell sensitization or neonatal alloimmunethrombocytopenia affecting the current pregnancy

• Maternal HIV, Hepatitis-B, Hepatitis-C status positive because of the increased riskof transmission to the fetus during maternal-fetal surgery. If the patient's HIV orHepatitis status is unknown, the patient must be tested and found to have negativeresults before enrollment

• Uterine anomaly such as large or multiple fibroids or Mullerian duct abnormality

• No safe or technically feasible fetoscopic approach to balloon placement

• Participation in another intervention study that influences maternal and fetalmorbidity and mortality or participation in this trial in a previous pregnancy.