Fetal Therapy for Congenital Diaphragmatic Hernia
Congenital diaphragmatic hernia (CDH) is a serious fetal condition in which an opening in the diaphragm allows abdominal organs to move into the chest. The displaced liver, stomach, and bowel can restrict lung development and interfere with the normal growth of the pulmonary circulation. After birth, affected infants may experience respiratory failure, pulmonary hypertension, and cardiac compromise.
Fetal therapy aims to improve the condition before delivery by reducing the effects of lung compression. The best-known approach is fetoscopic endoluminal tracheal occlusion (FETO), a minimally invasive procedure that temporarily blocks the fetal trachea. It is offered only to carefully selected pregnancies within specialist fetal medicine programs and alongside detailed counseling.
Management has advanced through collaboration among maternal-fetal medicine specialists, fetal surgeons, neonatologists, pediatric surgeons, anesthesiologists, radiologists, and researchers. The perinatal focus associated with the FAOPS 2020 congress archive reflects the same need for coordinated care across diagnosis, intervention, delivery, and neonatal stabilization.
How Congenital Diaphragmatic Hernia Affects Development
CDH usually results from incomplete formation of the diaphragm early in gestation. The size and location of the defect vary, as does the amount of abdominal content that enters the thorax. Left-sided defects are more common, although right-sided hernias can also be severe and may be harder to characterize prenatally because the liver has a similar appearance to the lung on ultrasound.
The principal concern is pulmonary hypoplasia, meaning that the fetal lungs do not develop enough functional tissue. The pulmonary vessels may also remain unusually muscular and narrow, leading to persistent pulmonary hypertension after birth. Severity is influenced by the observed-to-expected lung-to-head ratio, liver position, defect size, genetic findings, and the presence of other structural abnormalities.
Prenatal ultrasound can identify the hernia and assess fetal growth, amniotic fluid, organ position, and lung size. Fetal magnetic resonance imaging may provide additional information about total fetal lung volume and liver herniation. Diagnostic testing, including chromosomal microarray or other genetic evaluation, is often discussed because CDH can occur with chromosomal or syndromic conditions.
Prenatal Assessment And Counseling
A fetal diagnosis should be followed by assessment at a tertiary referral center with experience in complex fetal anomalies. The family typically meets a multidisciplinary team that explains the expected range of outcomes rather than presenting a single prediction. Evaluation includes detailed imaging, echocardiography, genetic counseling, and review of the planned delivery hospital and neonatal resources.
The observed-to-expected lung-to-head ratio is commonly used to classify pulmonary hypoplasia, particularly in left-sided CDH. A very low measurement, especially when the liver is in the chest, indicates a greater risk of severe neonatal respiratory disease. These measurements are useful for counseling, but they are not perfect; technical factors, gestational age, examiner experience, and the biological variation of CDH can affect interpretation.
Counseling should cover expectant management, fetal intervention when appropriate, possible preterm premature rupture of membranes, preterm birth, procedure-related complications, and the possibility that fetal therapy will not prevent the need for advanced neonatal support. Parents also need a clear explanation of neonatal treatment, which may include gentle ventilation, inhaled nitric oxide, pulmonary vasodilators, and extracorporeal membrane oxygenation (ECMO).
How Fetoscopic Tracheal Occlusion Works
FETO is performed by placing a small fetoscope into the fetal airway and positioning a removable balloon within the trachea. Blocking the trachea prevents the escape of lung fluid, allowing pressure to build within the developing lungs. That pressure may stimulate lung growth and improve pulmonary vascular development before the balloon is removed.
The procedure is usually considered during a defined gestational window, with timing influenced by disease severity, local protocol, and the findings of the multidisciplinary assessment. Balloon removal is essential before or during delivery so that the newborn can breathe and receive ventilation. Removal may be performed fetoscopically before labor or through an EXIT-style procedure at a specialist center, depending on the clinical plan.
FETO is not a universal treatment for CDH. It is most often considered for fetuses with severe pulmonary hypoplasia and selected anatomical features. The intervention requires repeated procedures, close ultrasound surveillance, and careful planning for balloon removal. Maternal risks can include preterm prelabor rupture of membranes, oligohydramnios, infection, bleeding, and complications related to anesthesia or fetoscopy.
| Clinical consideration | Why it matters | Typical management focus |
|---|---|---|
| Lung size | Estimates the degree of pulmonary hypoplasia | Serial ultrasound and specialist counseling |
| Liver position | Indicates the extent of thoracic compression | Helps assess severity and eligibility for FETO |
| Genetic or structural findings | May change prognosis and treatment goals | Genetic testing and detailed fetal imaging |
| Balloon placement | Determines whether tracheal occlusion is effective | Fetoscopic surveillance and procedural expertise |
| Balloon removal | Is necessary for neonatal airway access | Planned fetoscopic, intrapartum, or postnatal removal |
| Delivery setting | Influences immediate survival and stabilization | Tertiary center with neonatal intensive care and ECMO access |
Evidence, Benefits, And Limitations
Clinical trials have shown that FETO can increase fetal lung volume in severe CDH and may improve survival in carefully selected cases. The potential benefit is greatest when the expected lung size is very low and the liver has entered the thorax. FETO has also been studied in moderate disease, where the balance between possible survival benefit and procedure-related harm is less straightforward.
The main limitation is that increasing lung size does not correct every problem associated with CDH. Pulmonary vascular disease, cardiac dysfunction, prematurity, infection, and other anomalies can still affect outcome. Some survivors require prolonged respiratory support, treatment for pulmonary hypertension, nutritional assistance, and follow-up for neurodevelopment, hearing, growth, and musculoskeletal health.
Families should therefore view fetal therapy as one part of a long care pathway, not as a guaranteed repair. Outcomes depend on the severity of the defect, gestational age at birth, response to treatment, neonatal stabilization, and the presence of associated conditions. Results from high-volume research centers may not apply directly to every hospital or patient population.
Delivery And Newborn Stabilization
Delivery planning is central to fetal treatment. Birth should generally occur in a center with maternal-fetal medicine, neonatology, pediatric surgery, pediatric anesthesia, advanced respiratory support, and access to ECMO when indicated. Routine early delivery is usually avoided because prematurity adds significant risk to an already vulnerable respiratory system.
After birth, the infant is commonly intubated promptly rather than receiving vigorous mask ventilation, which can force air into the stomach and bowel and further compress the lungs. A nasogastric or orogastric tube is placed for decompression. Ventilation is gentle and carefully monitored to limit ventilator-induced lung injury while maintaining adequate oxygenation and circulation.
The neonatal team evaluates blood gases, blood pressure, cardiac function, pulmonary pressures, and response to ventilation. Inhaled nitric oxide, vasoactive medicines, high-frequency ventilation, or ECMO may be used when conventional support is insufficient. Pediatric surgeons repair the diaphragm after the infant is physiologically stable; immediate surgery is not always the safest approach.
Specialist guidance on neonatal brain protection, including therapeutic hypothermia best practices, illustrates a wider principle in perinatal medicine: stabilization and protection of vulnerable organs must be integrated into the treatment plan rather than considered separately from the primary diagnosis.
Selecting Candidates For Fetal Intervention
Eligibility for FETO depends on the diagnosis, severity, gestational age, maternal health, fetal anatomy, and the capabilities of the treating center. Severe left-sided CDH with markedly reduced lung size is the clearest setting in which fetal tracheal occlusion may be discussed. Moderate cases may be considered under research protocols or specialized programs with defined selection criteria.
Before accepting the procedure, families should understand the practical demands of treatment. These may include travel to a referral center, frequent ultrasound examinations, hospitalization or proximity to the hospital, balloon removal, possible early delivery, and long-term neonatal care. The mother’s wellbeing and preferences are essential to the decision.
A structured consultation can help families organize the main issues:
- Confirm the CDH diagnosis and assess liver position, lung size, heart function, and associated abnormalities.
- Discuss genetic testing and whether additional fetal imaging could refine the prognosis.
- Compare expectant management with FETO, including the expected benefits and maternal and fetal risks.
- Identify the planned site of delivery, neonatal intensive care capacity, pediatric surgical expertise, and ECMO availability.
- Establish how balloon removal, preterm birth, respiratory failure, and long-term follow-up would be managed.
Long-Term Care And Research Priorities
Survival from CDH is only the first outcome considered by modern perinatal teams. Children may need monitoring for chronic lung disease, recurrent respiratory symptoms, gastroesophageal reflux, feeding difficulty, growth problems, hearing impairment, developmental delay, and recurrence or complications related to the diaphragm repair. Follow-up should be coordinated across neonatology, pulmonology, cardiology, surgery, nutrition, and developmental services.
Research continues to refine fetal imaging, improve severity prediction, and determine which patients gain the greatest advantage from FETO. Investigators are also studying balloon design, safer methods of placement and removal, timing of occlusion, and ways to reduce the risk of membrane rupture and prematurity. International registries and prospective trials are important because CDH is relatively uncommon and outcomes can vary substantially between centers.
The central goal is individualized care. Fetal therapy may offer a meaningful survival benefit for selected pregnancies with severe pulmonary hypoplasia, but it must be delivered within a complete perinatal strategy. Accurate diagnosis, realistic counseling, experienced procedural care, and expert neonatal stabilization all contribute to the best possible outcome.
Families and clinicians seeking authoritative information should review current trial data and referral pathways with a qualified fetal medicine team. Early consultation allows time for imaging, genetic evaluation, shared decision-making, and delivery planning—essential steps when considering advanced treatment for congenital diaphragmatic hernia.
