Fetal Endotracheal Occlusion (FETO) in Severe and Extremely Severe Congenital Diaphragmatic Hernia

A Prospective Study of the Effectiveness of Fetal Endotracheal Occlusion (FETO) in the Management of Severe and Extremely Severe Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) occurs when the diaphragm fails to fully fuse and leaves a portal through which abdominal structures can migrate into the thorax. In the more severe cases, the abdominal structures remain in the thoracic cavity and compromise the development of the lungs. Infants born with this defect have a decreased capacity for gas exchange; mortality rates after birth have been reported between 40-60%. Now that CDH can be accurately diagnosed by mid-gestation, a number of strategies have been developed to repair the hernia and promote lung tissue development.

Fetal tracheal occlusion is one technique that temporarily closes the herniated area with the Goldvalve balloon to allow the lungs to develop and increase survival at birth. This is a pilot study of a cohort of fetuses affected by severe CDH that will undergo FETO to demonstrate the feasibility of performing the procedure, managing the pregnancy during the period of tracheal occlusion, and removal of the device prior to delivery at BCM/Texas Children's Hospital (TCH). It is anticipated that fetal tracheal occlusion plug-unplug procedure will improve mortality and morbidity outcomes as compared with current management, but this is not a primary endpoint of the feasibility study. We will perform 20 FETO procedures on fetuses diagnosed prenatally with severe and extremely severe CDH.

Enrollment

Women carrying fetuses with severe or extremely severe CDH and a normal karyotype will undergo routine clinical evaluation. The fetuses will be 27+0/7 to 29+6/7 weeks of gestational age for severe CDH and can be as early as 22+0/7 weeks gestational age for those deemed as "extremely severe" cases of CDH. They will have ultrasound and/or MRI evaluation to rule out other anomalies, calculation of the LHR from ultrasound measurements, echocardiography, and detailed obstetric/perinatal consultation. Patients who meet the eligibility criteria will be extensively counseled, and those who wish to participate will provide written, informed consent for the study.

Procedure

The procedure will be performed under spinal anesthesia or local anesthesia with intravenous sedation. The technique of fetal endoscopic tracheal occlusion has been described. Using standard technique, a cannula loaded with a pyramidal trocar will be inserted into the amniotic cavity and a fetoscope or flexible operating endoscope will be passed through the cannula into the amniotic fluid. If, upon evaluation, the baby cannot be accessed through the way just described above, the uterus will be accessed through an incision in the belly (called a laparotomy). A laparotomy is a surgical technique that makes an incision in the abdomen. After the incision has been made, the uterus will be temporarily repositioned externally. The baby will then be accessed using the fetoscope and ultrasound, as described above. The laparotomy will only be done if the baby cannot be reached and repositioned to a more favorable one by doing external maneuvers (called external version) for the FETO procedure.

The scope will be guided into the fetal larynx either through a nostril and then via the nasal passage or through the fetal mouth, and then through the fetal vocal cords with the aid of both direct vision through the scope and cross-sectional ultrasonographic visualization. A detachable latex balloon will be placed in the fetal trachea midway between the carina and the vocal cords. The balloon will be inflated with isosmotic contrast material so that it fills the fetal trachea.

Postoperative

The mothers will be discharged once stable. Serial measurements of sonographic lung volume and LHR will begin within 24-48 hours following surgery and continue weekly by targeted ultrasound evaluation. Amniotic fluid level and membrane status will also be monitored at weekly intervals. Comprehensive ultrasonography for fetal growth will be performed every four weeks (+/- 1 wk). All discharged patients will stay within 30 minutes of TCH to permit standardized postoperative management and emergent retrieval of the balloon in the event of preterm labor or premature rupture of membranes prior to the scheduled removal.

After the FETO surgery, prior to leaving the hospital, the mother will be given a medical alert bracelet identifying her as a patient with a baby with blocked airways. She will be encouraged to wear the bracelet at all times so that in case of emergency, she and others will know who to contact. She will also be given a pamphlet with instructions for medical personnel describing how to remove the balloon in case of an emergency. She should carry it with her at all times.

Balloon retrieval will be planned at between 32+0/7 and 34+6/7 weeks or no longer than 10 wks after placement, at the discretion of the FETO center. The patient will need to commit to remaining in 30 minutes of Texas Children's Hospital Pavilion for Women until the balloon is retrieved. In the event of a patient relocating after having the balloon placed, despite having committed to remain in the area during consent process, she will be asked to return for the removal. Every effort to make arrangements for her to be managed by the nearest center capable of an EXIT procedure or balloon retrieval (San Francisco or Philadelphia) will be made.

After removal of the balloon, patients will have the choice of delivering at Texas Children's Hospital- Women's Pavilion with the CDH managed and repaired at TCH, or returning to their obstetrician for delivery with subsequent repair of the CDH by the pediatric surgeons at their referring facility. Given the severity of the CDH, the baby will need to be delivered in a facility that has the capability of immediate pediatric surgery services.

We will need to monitor the baby at regular intervals (at 6 weeks, 3 months, 6 months, 1 year, and 2 years) after delivery to see how well the baby is breathing and how well the baby is developing. These check- ups may be at Texas Children's Hospital- Women's Pavilion or can be coordinated with other doctors of the participant's choosing.

If the child continues care at another institution, we will attempt to follow up with a review of the child's medical records.

INCLUSION CRITERIA:

• Patient is a pregnant woman between 18 and 45 years of age
• Singleton pregnancy
• Confirmed diagnosis of severe or extremely severe left, right or bilateral CDH of the fetus

Severe CDH: -Fetal liver herniated into the hemithorax -Lung-head ratio (LHR) is less than or equal to 1.0 calculated between 27+0/7 and 29+6/7 weeks' gestation

Extremely Severe CDH: -At least 1/3rd of the liver parenchyma herniated into the thoracic cavity -Lung-head ratio (LHR) is < 0.71 calculated between 22+0/7 and 29+6/7 weeks' gestation

• Normal fetal echocardiogram or echocardiogram with a minor anomaly (such a small VSD) that in the opinion of the pediatric cardiologist will not affect postnatal outcome
• Normal fetal karyotype
• The mother must be healthy enough to have surgery
• Patient provides signed informed consent that details the maternal and fetal risks involved with the procedure
• Patient willing to remain in Houston for the duration following the balloon placement until delivery
• Signed informed consent

EXCLUSION CRITERIA:

• Contraindication to abdominal surgery, fetoscopic surgery, or general anesthesia
• Allergy to latex
• Allergy or previous adverse reaction to a study medication specified in this protocol
• Preterm labor, preeclampsia, or uterine anomaly (e.g., large fibroid tumor)
• Fetal aneuploidy, known structural genomic variants, other major fetal anomalies, or known syndromic mutation
• Suspicion of major recognized syndrome (e.g. Fryns syndrome) on ultrasound or MRI
• Maternal BMI >40
• High risk for fetal hemophilia