Fascinating Fetal Finds: Fetal Neck Teratoma
A large fetal neck teratoma is a very rare malformation. While the exact cause is unknown, these masses are composed of several types of embryonic tissue and appear on ultrasound and fetal MRI as large masses containing both cystic and solid components. The masses can cause complications during pregnancy as the mass displaces the normal structures of the neck. It can interfere with the fetus’ ability to swallow by compressing and obstructing the throat and esophagus. This results in polyhydramnios, increased amniotic fluid volume, and can be associated with higher risks of preterm labor, preterm rupture of the membranes and placental abruptions. These masses can also distort and compress the structures of the upper airway. At the time of delivery, this can make the establishment of an adequate airway in the newborn very difficult.
A 21-year-old woman was transported to Children’s Memorial Hermann Hospital at 28 weeks and 1 day gestation. Her pregnancy
had been complicated recently by the diagnosis of a large fetal neck mass and polyhydramnios, with an amniotic fluid index (AFI)
of 34 cm. The patient began to experience uterine contractions earlier that day resulting in the request for transfer. An ultrasound evaluation performed by The Fetal Center at Children's Memorial Hermann Hospital at the time of admission confirmed the presence of a large mass consisting of cystic and solid components originating from the neck of the fetus. The overall size of the mass was calculated from 3-D reconstruction at 346 cc and was more left-sided, but it also extended across the anterior aspect of the neck to the right side. The fetal neck was extended and tilted to the right by the mass. There was no apparent invasion of the oropharynx. The stomach could not be visualized and was thought to be secondary to esophageal compression by the mass. The cervical length measured 3.4 cm.
Initial management was directed toward the threatened preterm labor. A fetal echocardiogram and ultrafast fetal MRI were obtained. The ECHO showed normal cardiac structure and function and the MRI confirmed the ultrasound findings (see Image 1, next page). The trachea was visible below the mass and was a normal caliber, suggesting there was no obstruction of the airway by the mass. The case was reviewed at The Fetal Center’s weekly multidisciplinary rounds and it was determined that the best course of management would be delivery by an ex-utero intrapartum treatment (EXIT) procedure. The family was extensively counseled and agreed with the management plan. The threatened preterm labor resolved and the mother remained in the hospital; the surgical team was on call, in case a complication developed.
One week later, re-evaluation on ultrasound showed the mass had enlarged to 861 cc. The polyhydramnios had increased with the AFI now measuring 44 cm. Evaluation of the cervix showed the cervix now measured only 3 mm, with bulging of the lower uterine segment. It was decided to perform the EXIT procedure despite the gestational age of 29 weeks 4 days.
A successful EXIT procedure was performed. It was possible to intubate the trachea from the oropharynx in spite of the distorted anatomy. The fetus was on placental support for 45 minutes. Once the airway was stabilized and the fetus well oxygenated, the
umbilical cord was cut and the newborn was transferred to the NICU for stabilization and surgical resection of the tumor. The maternal recovery was uncomplicated.
Early diagnosis of a fetal neck mass is essential to the development of a strategic plan to optimize the delivery and postnatal management of the newborn. The EXIT procedure is the foundation of that strategy and has been shown to be an effective method for delivery of patients with potential airway obstruction at birth. The fetus is partially delivered but maintained on placental circulation to provide ongoing oxygenation and support. This allows access to the fetal airway in an elective, controlled and secure manner.
Once an airway is secured, the rest of the fetus is delivered, the umbilical cord is clamped and the newborn transferred to the neonatal team for stabilization. While simple in concept, the success of an EXIT procedure relies on extensive preoperative evaluation to determine feasibility, careful planning and the availability of a highly skilled multidisciplinary team.
The Fetal Center is one of the few centers in the world where such expertise exists. The EXIT procedure is a well-organized, multidisciplinary treatment plan; it is the optimal treatment plan for a number of other conditions where problems are anticipated with the baby’s ability to breathe at the time of delivery.
The EXIT procedure is not without risk for both mother and newborn. The level of general anesthesia required to achieve uterine relaxation contributes to risks for increased bleeding. Postnatal care of the newborn can involve prolonged hospitalization. In addition to resection of the tumor, many newborns have underlying pulmonary hypoplasia from the neck mass distorting normal lung development. Many are born prematurely and thyroid/parathyroid gland dysfunction is common following resection of the tumor.
The Fetal Center was the first in Texas to perform the EXIT procedure, which is utilized when doctors are concerned that the baby may not be able to breathe adequately on its own following delivery. This can be for several reasons, including
problems with the lungs or masses of the neck or chest that may be compressing the airway. Such indications may include, but are not limited to:
- Large fetal neck masses
- Congenital diaphragmatic hernias
- Congenital high-airway obstructions
- Lung masses
- Chest or mediastinal tumors
The early diagnosis and multidisciplinary management of patients in a tertiary care facility is important to the delivery plan. For more information, contact us at (832) 325-7288 or firstname.lastname@example.org