Fetal Neck Masses

A fetal neck mass is an abnormal growth in the neck that affects babies before they are born. In severe cases, the neck mass can block a baby’s airway or esophagus, causing breathing problems at birth or preventing a baby’s ability to swallow. Obstruction of the esophagus in particular may also lead to the build-up of amniotic fluid in the womb (polyhydramnios), which can then cause preterm labor.

At the SSM Health Cardinal Glennon St. Louis Fetal Care Institute, we understand the anxiety and worry you may have about a fetal neck mass diagnosis. Our doctors are specially trained to help you and your baby, providing the care, advanced monitoring and the treatment plan you and your baby deserve.

In many cases, a neck mass can be managed after your pregnancy and delivery. However, when a neck mass obstructs the breathing airway or esophagus, we will consider a variety of interventions to provide the best care for you and your baby.

What Causes Fetal Neck Masses?

Fetal neck masses are rare and usually there is no genetic cause. The most common type of fetal neck mass - cystic hygroma (also known as a cervical lymphatic malformation or lymphangioma) - is caused by an abnormality in the development of the lymphatic channels in the neck. A cervical teratoma - another, rarer, kind of neck mass - is usually caused when reproductive cells become abnormally located in the neck and begin to grow.

How is a Fetal Neck Mass Diagnosed and Evaluated?

A fetal neck mass is typically detected by an ultrasound around 20 weeks gestation. When you are referred to the Cardinal Glennon St. Louis Fetal Care Institute with a fetal neck mass diagnoses, our team of specialists will perform an in-depth evaluation to determine the size and impact of the mass on your baby. This evaluation includes:

  • Frequent ultrasounds
  • A fetal echocardiogram: ultrasound of the heart performed by a pediatric cardiologist
  • A fetal MRI to determine the nature and size of the mass, as well as how it is impacting the airway, esophagus and other surrounding organs

With all of this information, the team can help you and your family make the best possible decision about treatment.

How Are Neck Masses Managed?

Throughout your pregnancy, our goal is to monitor the neck mass and determine if it’s growing, and how it may impact your baby.

Currently, there is not a prenatal surgery option for fetal neck masses. However, if there is too much amniotic fluid (polyhydraminos), amnioreduction may be performed to remove the excess fluid, and lower the risk of preterm labor. During an amnioreduction, a local anesthetic is used to numb the skin of the mother’s abdomen, then a needle is inserted into the womb to remove the excess amniotic fluid. The baby is monitored via ultrasound throughout the procedure to ensure it is not touched by the needle. Additionally, the mother may also be placed on bed rest, or given special medications to reduce the amniotic fluid.

How Will a Fetal Neck Mass Impact Delivery?

In most cases, babies with a small neck mass can be delivered vaginally with a low risk of complications. After you go home, we follow you as an outpatient for two to four weeks. During this time, we’ll refer your baby to a pediatric surgeon who will determine if and when your baby requires a surgery to remove the mass.

EXIT Procedure

In severe cases, a large neck mass can prevent a baby from breathing at birth. If this happens, an EXIT (Ex Utero Intrapartum Treatment) procedure may be performed for your delivery.  During EXIT, you will give birth by C-section while asleep under general anesthesia. This will allow the surgeon to evaluate and treat your baby’s airway while your baby’s placenta and umbilical cord remain attached.

What Can I Expect After My Baby is Born With a Fetal Neck Mass?

Babies who are born with a fetal neck mass often have difficulty breathing and eating at birth. If the neck mass compresses your baby’s airway, your baby may need a tracheostomy (a surgical opening in the trachea, often called a breathing tube) to make breathing easier. A temporary feeding tube to help provide nutrition may also be necessary if your baby is unable to swallow at birth.

After your baby is stabilized, the treatment of choice for a neck mass is surgery. In most cases, babies who receive surgery for a neck mass go on to develop normally without problems. However, it will be important for your child to receive ongoing follow-up care as they will have a higher chance of mass re-growth.

We understand that a neck mass can be a scary diagnosis. That’s why we’re available to help 24 hours a day, 7 days a week. For more information or to schedule an appointment, call us at 314-268-4037 or toll free at 877-SSM-FETL (877-776-3385). You can also email us and one of our trusted representatives will get back to you as soon as possible.

Throughout your journey, our team is here to provide you the expert care and support your need, helping you and your baby get the most out of treatment - and life.

Patient Stories About Fetal Neck Masses

little girl dressed like a ladybug laughing at camera


At the St. Louis Fetal Care Institute, we understand the fear and confusion that come with the diganosis of a prenatal medical condition. We share these patient stories to offer comfort, hope, and inspiration from other parents who have been where you are. Know that you are not alone - our team is here to support you every step of the way.

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