Keywords
EXIT-to-airway - fetal neck mass - monochorionic - dichorionic - lymphatic malformation
- cervical teratoma - twin pregnancy - airway obstruction
Congenital neck masses can obstruct the fetal airway during development, compromising
the ability of the newborn to breathe at birth which carries a high risk for hypoxic
brain injury and death.[1]
[2] The ex-utero intrapartum treatment (EXIT) procedure was developed to prevent catastrophic
airway obstruction occurring at the time of birth and has been successfully applied
to the treatment of congenital neck masses.[3]
[4]
[5]
[6] In contrast with a normal cesarean delivery, an EXIT procedure requires general
anesthesia and the administration of tocolytic medications to maintain uterine relaxation
and stable uteroplacental circulation.[7] Stable gas exchange through the umbilical circulation provides time to secure the
airway before delivering the baby.[8] Fetal airway obstruction in twin pregnancy presents a unique challenge, especially
in monochorionic pregnancies, as disruption of the placental circulation during delivery
of the affected twin invariably exposes the bystander twin to increased risk. Very
few cases of EXIT procedures for twin pregnancy have been reported.[6]
[9]
[10]
[11]
[12] Here, we report a singular methodology for EXIT-to-airway procedures in both monochorionic
and dichorionic twin pregnancies.
Case Presentation
Case 1
A 33-year-old G6P2 patient was referred at 26 weeks gestation for the evaluation of
her monochorionic-diamniotic pregnancy complicated by a large neck mass in one twin
(Twin B). A large, exophytic, mixed solid, and cystic mass was found on fetal ultrasound
and magnetic resonance imaging (MRI; [Fig. 1]) arising from the anterior neck. There was compression of the cervical trachea and
massive polyhydramnios on the side of the affected fetus (deepest vertical pocket
[DVP] = 20 cm) and normal DVP on the side of Twin A (4.6 cm). No other anomalies were
identified, and there were no insufficient criteria for the diagnosis of twin–twin
transfusion syndrome. The bystander twin (Twin A) was normal. The diagnosis of a cervical
teratoma was made, and the patient was counseled by the multidisciplinary team about
the potential risk of airway compromise of Twin B at birth. Given the size of the
neck mass and the need for cesarean delivery, an EXIT-to-airway procedure was recommended
at the earliest 28 weeks. Amnioreduction was discussed; however, preference was given
toward indomethacin for fetal antidiuretic effect, as the vasa previa present in Twin
A increased the risk of complication during amniocentesis. The risks and benefits
of the procedure for the mother and both babies were discussed. The massive amniotic
sac established Twin B as the presenting twin for any approach. A plan for airway
management of Twin B while on placental bypass with dual fetal monitoring was created
by the multidisciplinary team including pediatric and fetal surgery, maternal–fetal
medicine, neonatology (two teams), obstetrical and fetal anesthesiology, otolaryngology,
and pediatric cardiology.
Fig. 1 Fetal MRI at 26 weeks gestation demonstrating a large exophytic, mixed solid and
cystic mass in Twin B resulting in tracheal compression.
At 29 weeks gestation, the patient presented with preterm labor. After a brief period
of observation, contractions increased in frequency and intensity. Cervical dilation
and significant effacement followed. The decision was made to perform an emergent
EXIT-to-airway procedure. The entire multidisciplinary team participated in the case.
A total intravenous anesthetic (TIVA) was administered and then transitioned to deep-inhaled
desflurane prior to the hysterotomy.
Through a midline incision, the uterus was exposed, and the placenta was carefully
mapped with ultrasound. An anterior fundal vertical hysterotomy was made to enter
the amniotic sac of Twin B. The fetal head and upper torso were delivered ([Fig. 2A]). An intramuscular cocktail of fentanyl, atropine, and rocuronium was administered
to the fetus. Uterine volume was maintained with continuous replacement with lactated
Ringer's solution. Continuous monitoring of both fetuses was obtained via transuterine
echocardiography (Twin A) or transthoracic echocardiography and pulse-oximetry (Twin
B). With anterior displacement of the tumor, rigid bronchoscopy was successfully performed.
A 2.5-mm endotracheal tube was passed ([Fig. 2B]). With hand ventilation, fetal oxygen saturation rose above 90%. The umbilical cord
was divided and the neonate was delivered to the neonatology team for resuscitation.
Fetal exposure time for Twin B was 22 minutes prior to delivery. Twin A was delivered
second, intubated and resuscitated by the neonatology team. The mother and Twin A
recovered from the EXIT procedure uneventfully. Following resuscitation, Twin B underwent
resection of the large cervical teratoma ([Fig. 2C,D]) and was discharged after a subsequent tracheostomy and 6-month NICU stay. Twin
B eventually required tracheal reconstruction and was later decannulated. Currently,
both twins are developing appropriately, as evidenced by the achievement of proper
developmental milestones on the Survey of Well-being of Young Children and normal
scores on the Preschool Pediatric Symptom Checklist (PPSC) performed at 48 months
(PPSC scores < 9, respectively).[13]
[14] They are both attending preschool and are independent of oxygen or airway support.
Fig. 2 Intraoperative photos of the EXIT procedure and neck mass resection. (A) Twin B partially delivered while remaining on uteroplacental bypass, with a large
neck mass resulting in tracheal compression. (B) Successful intubation of Twin B. (C) Resection of the multicystic mass and dissection from the anterior surface of the
trachea. (D) Final surgical incision after resection.
Case 2
A 33-year-old G2P1 patient was referred at 24 weeks gestation for the evaluation of
her dichorionic-diamniotic pregnancy with one twin (Twin B) affected by a large cervical
mass. On fetal ultrasound and MRI, a 10 × 6.4 × 5.9 cm multicystic mass was identified
in Twin B involving the anterior and lateral left neck extending to the floor of the
mouth and hypopharynx. Polyhydramnios was present (DVP = 10 cm). The remainder of
the fetal evaluation was reassuring without any other malformation detected. The diagnosis
of multicystic lymphatic malformation was made. The patient was similarly counseled
by the multidisciplinary team about the potential risk for airway compromise of Twin
B at birth, and an EXIT-to-airway procedure was recommended. The risks and benefits
of the procedure for the mother and both babies were discussed. A similar algorithm
was developed for the EXIT procedure.
Because of the progressive polyhydramnios and twin gestation, the EXIT-to-airway procedure
was scheduled at 36 weeks of gestation. A similar multidisciplinary team attended
the procedure, and a similar TIVA/desflurane anesthetic was administered. Through
a midline incision, the uterus was exposed, and the placenta was carefully mapped
with ultrasound. A posterior fundal hysterotomy was made to selectively enter the
amniotic sac of the affected Twin B and expose the fetal head. The fetal head and
upper torso were delivered and fetal anesthetic cocktail administered. Continuous
monitoring of both fetuses was obtained via transuterine echocardiography (Twin A)
or transthoracic echocardiography and pulse-oximetry (Twin B). An endotracheal tube
was passed with the assistance of rigid bronchoscopy. With hand-ventilation, the fetal
oxygen saturation rose above 90%. The umbilical cord was divided and the neonate delivered
to the neonatology team for resuscitation. Fetal exposure time for Twin B was 10 minutes
prior to delivery. The bystander twin (Twin A) was delivered second, intubated and
resuscitated by the neonatology team. The mother recovered from the EXIT procedure
uneventfully. After delivery, Twin A was extubated within 1 hour after admission to
the neonatal intensive care unit, rapidly weaned to room air, and was discharged from
the hospital without issue after 2 days of observation. Twin B underwent partial resection
of the neck mass at 4 months and is currently undergoing sclerotherapy for his multicystic
lymphatic malformation. Both children are developing appropriately, with achievement
of all developmental milestones on formal evaluation by their pediatrician at 2 years
old.
Discussion and Conclusion
Discussion and Conclusion
In fetal surgery, the pregnant patient is always considered the primary patient, entitled
to take the risk for the potential benefit of her fetus. Twin gestation represents
a unicum in fetal and perinatal medicine, especially when one of the twins presents
a severe congenital malformation. In twin pregnancy affected by a congenital malformation,
the health of the co-twin impacts the decision-making, as the mother and health care
providers may accept additional risk for an otherwise healthy fetus.
These cases demonstrate the complex decision-making required for the management of
fetal neck masses in twin pregnancy. In one fetus, the lesion would compromise the
fetal airway at birth, potentially leading to hypoxia and death. However, treatment
of the affected twin via an EXIT procedure introduces the potential for compromise
of the bystander twin, which could otherwise be minimized via alternative approaches.
The EXIT-to-airway technique allows for adequate airway management and has the potential
to prevent respiratory distress in the affected fetus but presents a risk of maternal
blood loss, placental abruption, or other acute causes of uteroplacental insufficiency
that compromise fetal oxygenation.[15]
[16]
[17]
[18] These risks augment with the duration of the procedure.[19] Thus, the EXIT procedure benefits the affected twin, but portends minimal if any
advantages for the bystander fetus. On the contrary, the risks of this approach fall
on both babies, so the advantages must be weighed not only against the risk for the
mother, but also against the additional risk for the bystander twin.
It is important to emphasize that both procedures were performed by a multidisciplinary
team with experience in hundreds of cases of open fetal surgery. Detailed preparation
and seamless communication are essential elements for safety and success. The decision
to proceed is thoroughly vetted among this team and with the patients. When presenting
this option to the parents, the health care providers must place a significant effort
on education of the mother, and each team must deliver an important perspective of
different perioperative risks and benefits. Additional review by an independent ethical
oversight committee is essential.
Beside the surgical insult, one must also consider the impact of prematurity. EXIT
procedures are scheduled as late as possible in gestation, but concurrent circumstances
may force an earlier delivery. For example, the polyhydramnios accompanying obstructing
fetal neck masses can prompt preterm labor.[20] Therefore, preterm delivery should be anticipated and the care plan developed accordingly.
In order to avoid emergent and unplanned delivery, EXIT is often performed earlier
than the due date but realistically, we feel that such a procedure would be appropriate
only after 28 weeks gestation. Nevertheless, this intervention can place the burden
of prematurity on the healthy bystander twin. If prematurity could be acceptable for
a newborn facing a near certain death, the similar risk imposed to a normal fetus
raises another serious ethical dilemma.
In the present paper, we demonstrate that EXIT-to-airway procedures are feasible even
when twins share a placenta. Additionally, we demonstrate that protection of the bystander
twin does not require its delivery first. On the contrary, due to the polyhydramnios
often present in this condition, it is likely that the affected twin's amniotic sac
will be encountered first during the hysterotomy and complicated maneuvers to avoid
it may ultimately compromise control of the procedure. In a prior twin-EXIT case,
Liechty et al noted that uterine tone increased after clamping the bystander twin's
umbilical cord, requiring additional tocolytic medication and potentially allowing
less time to treat the affected twin.[21] Rather, a well-controlled hemostatic entry into the affected twin's sac preserves
adequate uteroplacental perfusion for both twins. Simultaneous cardiac monitoring
of both fetuses and an alternate rescue algorithm provide measured safety and yield
outcomes similar to EXIT procedures in singleton pregnancies.
In conclusion, even in monochorionic-diamniotic gestation, EXIT-to-airway procedures
are feasible with good outcomes for the mother and twins. Establishing the airway
and delivery of the affected twin prior to delivery of the bystander twin is safe
and facilitates stable uteroplacental perfusion during the delivery. We also strongly
advise continuous cardiac monitoring of both fetuses throughout the procedure and
alternative delivery of both babies with the development of fetal distress. A multidisciplinary
approach and advanced planning are paramount for optimal outcomes.
