Congenital Diaphragmatic Hernia (CDH)
Congenital diaphragmatic hernia (CDH) is a sporadic birth defect that occurs in 1 in 3,000 pregnancies. The diaphragmatic defect produces herniation of the abdominal organs into the thoracic cavity, which results in pulmonary hypoplasia (underdevelopment of the lungs). Approximately 80% of CDH’s are left-sided, 15% right-sided and 5% are bilateral. Overall perinatal mortality risk remains as high as 50% despite advances in prenatal diagnosis and neonatal intensive care.
In view of the high morbidity and mortality, in utero (in the womb) correction of CDH has been attempted. Animal experiments had shown that pulmonary hypoplasia could be prevented, thereby allowing for lung growth. It is common knowledge that the fetus has a net outward flow or movement of fluid from the lungs. This notion was used to consider intentional temporary obstruction (blockage) of the fetal airway to produce expansion of the lungs to avoid the development of pulmonary hypoplasia. Experimental data have suggested that lung growth can be enhanced following this intervention due to mechanical stretching forces from the increased hydrostatic lung fluid pressure. However, despite a gross increase in lung mass, sustained fetal tracheal occlusion can cause abnormalities in the lung as well.
Understanding that normal fetal lung growth and maturation may be related to both tonic stretching forces due to in utero pulmonary fluid secretion as well as cyclic stretching forces from intermittent fetal breathing activity, the concept of intermittent tracheal occlusion arose. The timing of the surgery and the method to occlude the trachea have been the subject of much research. The current clinical strategy is to provide tracheal occlusion between weeks 26-28 followed by removal of the occlusion at 34 weeks gestation, although there remains controversy regarding timing and duration of occlusion.
Recent studies on human fetuses with CDH have shown success in treatment using fetal endoscopic tracheal occlusion. We are currently in the process of setting up a study to perform percutaneous endoscopic placement using a novel tracheal occlusive device. Our objective is to evaluate by observation the use of an intraluminal device for the treatment of congenital diaphragmatic hernia in utero.
Patients with congenital diaphragmatic hernia will be eligible for the study if they meet the following criteria:
- Absence of other major congenital anomalies (e.g., congenital heart disease).
- Normal karyotype
- Thin/non-obese complexion (<180 lbs.)
- Local patient, or patient willing to remain in Los Angeles for the duration of the pregnancy
- Gestational age at time of diagnosis: less than 25 weeks of gestation
- Gestational age up to 30 6/7 weeks
- Any severe congenital diaphragmatic hernia:
- Right-sided hernia; or
- Left-sided hernia with relatively small right lung volume (lung-to-head circumference ratio of less than or equal to 0.9); or
- Left-sided hernia with liver herniation into the left hermithorax (“liver-up”)
- Patients unwilling to participate in the study or to be managed by our group here in Los Angeles
- Presence of major congenital anomalies
- Abnormal karyotype
- Ruptured membranes
- Diagnosis made after 25 weeks gestation and (except for right-sided CDH) a right lung area to head circumference ratio greater than 0.9
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