Large neck masses, such as cervical teratomas or lymphangiomas, can grow to such large proportions that the fetal airway becomes distorted and obstructed, according to specialists at the University Center for Fetal Medicine. In a small number of patients with cervical teratomas, the mass effect pulls the lungs into the apex of the chest and results in pulmonary hypoplasia.
In addition to obstructing the airway, these giant neck masses can compress the esophagus, resulting in polyhydramnios, which can lead to uterine irritability and preterm labor. Unsuspected obstructive fetal neck masses often prove fatal at delivery because of an inability to secure an airway and ventilate the neonate, which results in hypoxia and acidosis. If the delay is longer than five minutes, anoxic brain injury may occur. This complication is all the more tragic because in most cases, this is an isolated anomaly and the children do well after postnatal resection.
Polyhydramnios can lead to a discrepancy between fetal size and dates and is a common indication for ultrasonography. When patients are referred to the University Center for Fetal Medicine with a diagnosis of a fetal neck mass based on this ultrasound finding, an in-depth evaluation is performed by our specialized multidisciplinary team. The mother undergoes a level II ultrasound detailing fetal growth and development as well as anatomy, with concentration directed toward the neck mass.
It is important to identify the type of neck mass and its relationship to adjacent structures. A complete obstetric history, physical and genetic evaluation are conducted to rule out other problems with the pregnancy that can cause polyhydramnios.
An ultra-fast fetal MRI is also performed to better define the anatomy, rule out other structural abnormalities and distinguish the various types of neck mass. A fetal echocardiogram helps assess any structural abnormalities of the heart. Parents are immediately counseled regarding treatment options. Pictured (right) is a MRI of a fetus with a large neck mass. The mass, indicated by the arrow, has a large cystic component as well as a smaller solid component, which are consistent with a cervical teratoma.
If the neck mass is small and does not compromise the airway, close ultrasound surveillance is warranted to follow the growth of the mass. If the mass grows to obstruct the esophagus and causes polyhydramnios, issues with preterm labor must be addressed. For example, the mother may be placed on bed rest, have some of the amniotic fluid removed and, in some instances, may receive a medication to decrease amniotic fluid. If the mass continues to grow and distort the airway, a specialized delivery procedure, called an EXIT procedure, is the treatment option of choice to secure the airway at delivery and allow the baby to breath.
The EXIT procedure is not just a cesarean section. A special uterine stapling device is used to open the uterus to prevent bleeding, and placental blood flow is maintained by relaxing the uterus with general anesthesia for the mother and maintaining uterine volume with saline infusion. This provides time to perform procedures, such as direct laryngoscopy, bronchoscopy or tracheostomy, to secure the airway as well as perform other therapies, such as surfactant administration, cyst decompression or even mass resection.
Pictured (right) is a fetus with a large neck mass, indicated by the arrow, during an EXIT procedure. In this photo, the fetus is undergoing direct laryngoscopy to identify the airway. Ultimately rigid bronchoscopy was required to establish the airway. After the airway was established and the ability to ventilate and oxygenate the baby was determined, the cord was clamped and divided. The baby was then taken to an adjacent operating room where the mass was successfully resected.
There are potential risks to the EXIT procedure. The risk of bleeding from uterine atony is minimized by coordination between the surgeon and anesthesiologist to decrease the concentration of inhaled anesthetia and administer oxytocin to contract the uterus before cutting the umbilical cord. This technique, in combination with the uterine stapling device, has minimized intra-operative maternal blood loss within the accepted range for traditional cesarean section.
Central to achieving an excellent outcome is the coordination of the University Center for Fetal Medicine's experienced team of pediatric surgeons, maternal fetal medicine specialists, fetal and maternal anesthesiologists, obstetricians and operating room nurses.