The EXIT procedure: principles, pitfalls, and progress.

Although performing procedures on a fetus before severing the umbilical cord has previously been reported, the principles of the ex utero intrapartum treatment (EXIT) procedure were first fully developed for reversing tracheal occlusion in fetuses with severe congenital diaphragmatic hernia. The EXIT procedure offers the advantage of insuring uteroplacental gas exchange while on placental support. The lessons learned in the development of the principles that underlie the EXIT procedure have improved outcomes when applied in other conditions, most notably in cases of airway obstruction. The range of indications for the EXIT procedure has expanded and currently includes giant fetal neck masses, lung or mediastinal tumors, congenital high airway obstruction syndrome, and EXIT to ECMO (extracorporeal membrane oxygenation), among others. This review summarizes the underlying principles of the EXIT procedure, the expanding indications for its use, the pitfalls of management, and the progress that has been made in its successful application.