Background: The EXIT (ex utero intrapartum therapy) procedure was initially designed for management of congenital diaphragmatic hernia. By leaving the fetus on uteroplacental bypass during the procedure, the fetal airway may be safely instrumented while maintaining up to 90 minutes of maternal-fetal circulation. Recently, we have expanded indications to include any fetus in which the resuscitation of the neonate may be compromised. This involves limited delivery of the head of the fetus, maintaining placental circulation, and managing airway, cardiac issues, and other critical issues prior to interruption of fetal/placental circulation.

Objective: To introduce the EXIT procedure as a safe method for management of the prenatally diagnosed micrognathic patient, and to integrate mandibular distraction into the armementarium of the fetal surgery team.

Methods: We have successfully distracted 7 neonates who had prenatal diagnosis of micrognathia and underwent EXIT procedure with tracheostomy and early distraction as part of an integrated team approach to congenital micrognathia. All patients had prenatal high resolution fetal ultrasound and fetal MRI prior to intervention. The distraction procedure was performed using a simple angle osteotomy and transfacial steinman pin fixation, rapid sequence distraction, and callus remodelling upon termination. Typical distraction sequence was 4mm/day.

Results: The mean gestational age at EXIT procedure was 35.0 weeks. Two of the fetuses exhibited profound micrognathia with polyhydramnios (n = 5), and underwent prenatal intervention. All patients underwent successful early distraction. Two of the patients have been successfully decannulated, although two have tolerated tracheostomy capping. All underwent gastrostomy placement as neonates. The average time on placental bypass was 50 minutes. Postnatal complications were minor in this group, and there was no indication for ECMO or other invasive support. Maternal prenatal complications included polyhydramnios (n = 3), preterm labor (n = 1). Average maternal blood loss was 835 ml. A single patient has undergone a second mandibular distraction for incomplete correction of a profound micrognathia. Average distraction was completed in 16 days, with mean distraction after callus manipulation of 33mm. There was no failure of distraction, hardware, or other surgical complications.

Conclusion: The EXIT procedure allows for controlled airway management in the perinatal period, significantly improving the safety of management of severe micrognathia. This technique dramatically reduces morbidity and mortality in this high risk group, and we believe it represents the safest method for treatment of severe congenital micrognathia.