Open Fetal Surgery at the End of Pregnancy
The EXIT Procedure
The EXIT (Ex Utero Intrapartum Treatment) Procedure is a highly modified Cesarean delivery which requires an experienced multi-disciplinary team. The goal is to partially deliver the baby, but maintain placental support to be able to perform surgery before the baby is completely delivered. Many technical aspects of open fetal surgery are utilized in the EXIT Procedure. The mother requires a general anesthetic to relax the uterus. The mother and fetus are extensively monitored during the procedure. A low transverse hysterotomy is preferred to allow for possible future vaginal deliveries. Special equipment including a hemostatic stapling device is utilized to prevent bleeding from the uterine edge. The fetus receives transplacental anesthesia, as well as additional anesthesia delivered intramuscularly. When the fetal procedure is completed and the baby is stable, the umbilical cord is divided and the baby is delivered. The maternal anesthetic management is changed and maternal medication is administered to cause the uterus to contract. The placental is removed, and the uterus and maternal abdominal wall are closed.
Cases Involving Anticipated Airway Obstruction at Birth
Conditions requiring an EXIT Procedure due to anticipated airway obstruction include giant neck masses (cervical teratoma / cervical lymphangioma) and congenital high airway obstruction syndrome (CHAOS). In these situations, the main goal is to obtain a secure airway while the baby is stable on placental support. Orotracheal intubation is performed with a standard breathing tube. If a breathing tube cannot be placed, then several different techniques including bronchoscopy are utilized. If these strategies fail, then a surgical airway (tracheostomy) is performed. In some cases, partial resection of the mass may be required to obtain a stable airway.
The EXIT-ECMO Procedure
The EXIT-ECMO procedure provides a smooth transition from the womb to ECMO (a heart-lung bypass machine) for babies with anticipated pulmonary or cardiac failure at birth. This technique avoids barotraumas, acidosis, hemodynamic instability and hypoxia. Patients with giant pulmonary masses (CCAM or pulmonary sequestration), rare heart tumors, and severe CDH (LHR<1.0, liver herniaiton, small lung volumes on fetal MRI) may be candidates for this procedure.
During the EXIT-ECMO procedure, the airway is secured and a trial of ventilation is performed. If the infant fails the trial of ventilation, ECMO cannulation is performed while the infant is stable on placental support. Once the infant is stabilized on ECMO, full delivery and clamping of the umbilical cord occurs. In some cases, an operation on placental support is necessary prior to ECMO.
