Ex Utero Intrapartum Treatment

Steven T Papastefan, M.D., Michael D. Puricelli, M.D., Inna Lobeck

Assessment

Neonatal stabilization with placental support was initially described in the context of fetal head and neck malformations resulting in airway obstruction at birth, with the intention of allowing for continued placental perfusion prior to securing the airway. The Operation on Placental Support (OOPS) was initially developed as a predecessor of the Ex Utero Intrapartum Treatment (EXIT) procedure to halt the third stage of labor, allowing for short duration fetal interventions of approximately 5-20 minutes [1][2]. This operation evolved into the EXIT procedure, which utilizes general anesthesia and inhaled anesthetic to provide uterine relaxation and preservation of uteroplacental blood flow, allowing for longer duration operations (mean 30-45 minutes, as long as 157 minutes reported) [3][4][5]. Since its inception, EXIT has been adapted to other time-sensitive fetal anomalies where neonatal resuscitation could be compromised. Several variations of the EXIT procedure exist for different fetal pathologies, namely EXIT to airway, EXIT to resection, EXIT to ECMO, EXIT to ventricular pacing, and EXIT to separation (see Table) [6][7][8][9].

The assessment of the patient for which an EXIT procedure is being considered varies based on the indication and perinatal intervention objective. All EXIT procedures require multidisciplinary collaboration involving a team composed of pediatric and/or fetal surgery, obstetrics, anesthesiology, and neonatology providers, with the addition of pediatric otolaryngology, cardiology, and other specialty providers depending on the indication.

Categories of EXIT procedures
Category	Potential Indications	Radiologic Assessment
EXIT to Airway	Head and neck masses (ie. cervical teratoma, lymphatic malformation)	Tracheoesophageal displacement index (TEDI) >12 Cervical vascular compression Floor of mouth involvement Presence of polyhydramnios Aerodigestive tract obstruction (absence of stomach bubble)
	Mandibular anomalies (ie. severe micrognathia)	Inferior facial angle < 50 Jaw index < 5th percentile Presence of polyhydramnios Aerodigestive tract obstruction (absence of stomach bubble)
	Congenital high airway obstruction syndrome (CHAOS)	Lung hyperexpansion Hyperechoic lungs Flattened/inverted diaphragm Mediastinal compression Polyhydramnios Fetal hydrops
	Iatrogenic (tracheal clip/balloon)	Labor in presence of tracheal occlusion balloon
EXIT to ECMO	This is a historic indication previosuly studied in the setting of CDH. Nowadays, it is replaced by C-section with ECMO standby
EXIT to ECMO	Congenital heart disease	Signs of heart failure on fetal echocardiography Fetal hydrops
EXIT to Resection	This is a historic indication in the setting of congenital lung lesions with better understanding of their natural history and the response to transplacental steroids
	Mediastinal masses	Mediastinal compression Fetal hydrops Polyhydramnios
	Sacrococcygeal teratoma	High risk of rupture and/or shunting High tumor to fetal weight ratio High output cardiac failure
EXIT to separation	Conjoined twins	Twins facing each other (difficult intubation) Dependence of one twin on the other for perfusion
EXIT to Ventricular Pacing	Complete fetal atrioventricular block (CAVB)	Complete atrioventricular block Ventricular rate < 55 bpm Ventricular function impairment (ie. Elevated myocardial performance index) [10] Fetal hydrops

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