Congenital high airway obstruction syndrome (CHAOS)

Congenital high airway obstruction syndrome (CHAOS) is a rare, serious birth defect in which the fetal airway is blocked.

The obstruction in the airway may be caused by:

• Blockage in the baby’s trachea (windpipe), or a missing section of the trachea
• Blockage or malformation in the larynx (voice box)
• A cyst (fluid collection) in the larynx
• Narrowing of the airway (known as stenosis)
• A membrane blocking the larynx or trachea

CHAOS can be a life-threatening condition. Babies with CHAOS require highly specialized care during pregnancy, delivery and after birth.

How does CHAOS affect my baby?

As the fetus develops, the lungs are constantly producing and expelling fluid. When the fetal airway is blocked, the fluid can’t escape out of the baby’s mouth, causing it to back up into the lungs.

The fluid-filled lungs become distended and continue to expand. This can lead to serious issues, including:

• Pressure on the heart that can affect its ability to function
• Accumulation of fluid in the trachea, bronchial tubes and abdomen
• Congestive heart failure
• Fetal hydrops: fluid accumulation in the baby’s body cavities and skin

Cause and Prevalence

CHAOS is extremely rare. The exact incidence, and the cause of the condition, are unknown.

Testing and Diagnosis

CHAOS is typically diagnosed during pregnancy through a routine ultrasound scan.

The ultrasound may show the fetus has:

• Enlarged lungs that are pressing against the heart, making it appear elongated
• An inverted diaphragm (curves downward, instead of upward)
• Abnormal breathing caused by the blockage

On referral to Texas Children’s Fetal Center®, we will arrange for a comprehensive evaluation and specialized care with a team of specialists experienced in treating CHAOS, including maternal-fetal medicine physicians, fetal and pediatric surgeons, neonatologists and fetal imaging experts.

You will undergo a full day of consultations and testing to help us gain more information about the severity of your baby’s airway obstruction and identify any associated conditions. 

Testing may include:

• Anatomy ultrasound to confirm the diagnosis, evaluate the airway and look for associated abnormalities
• MRI for more detailed information about the airway, the extent of blockage and any other conditions present
• Fetal echocardiogram to evaluate the baby’s heart function and detect any heart defects
• Amniocentesis and chromosomal analysis to look for chromosome abnormalities

At the end of the day, we will meet with you about your results and provide recommendations based on the unique needs of your baby, to help you make the most informed decisions regarding care and treatment. 

Treatment During Pregnancy and Delivery

You and your baby will be closely monitored throughout your pregnancy, with regular ultrasounds to assess the baby’s condition and look for early signs of hydrops, a build-up of excess fluid in the fetus that may signal impending heart failure and can be fatal.

Treatment during pregnancy will depend on your baby’s gestational age when CHAOS is diagnosed and if hydrops is present. In severe cases involving fetal heart failure and hydrops, fetal surgery to eliminate the obstruction may be an option.

Babies with CHAOS are at high risk of breathing difficulties at birth. Your doctor may recommend you deliver via a scheduled cesarean section, with a special procedure planned at delivery known as EXIT (ex utero intrapartum treatment) to provide your baby an airway for breathing before being separated from the placenta. The goal is to ensure the baby isn’t deprived of oxygen at birth, minimizing the risk of brain damage.

If the fetus develops hydrops before your scheduled delivery date, early delivery may be necessary. Early delivery may also be recommended if mom develops syndromes that ‘mirror’ fetal hydrops including high blood pressure, swelling and liver problems, as these can be life-threatening.

Here at Texas Children’s Fetal Center, we are prepared to help facilitate the best possible outcome. We are equipped to provide the highly specialized care required for babies with CHAOS, including advanced fetal diagnostics and surgeries, and the highest level of neonatal intensive care. Delivery and postnatal care should be carefully planned and coordinated with a team of maternal-fetal medicine specialists, neonatologists, anesthesiologists and surgeons experienced in the EXIT procedure.

What is an EXIT Procedure?  

In an EXIT procedure, the mother’s abdomen and uterus are opened, as in a C-section, and the baby’s head and part of the upper body are delivered. While the baby is still attached to the placenta via the umbilical cord, and receiving oxygen from the mother, the surgeon evaluates the airway and inserts a breathing tube to create an artificial airway, enabling the baby to breathe after delivery. When the baby is stable enough, the newborn is then fully delivered and the umbilical cord is cut.

If possible, the obstruction may be surgically repaired at the time of the EXIT procedure.

Treatment After Birth

Following an EXIT procedure, your baby will be taken to a neonatal intensive care unit (NICU) for observation and care. In some cases, the baby may need to be placed on ECMO (extracorporeal membrane oxygenation), a heart-lung bypass machine that performs the work of the heart and lungs.

Additional surgeries may be required after birth to remove the blockage and reconstruct the airway.

Long-Term Outcomes

While there is limited information on long-term outcomes because of the rarity of CHAOS, in general outcomes will depend on the cause and severity of the airway obstruction, and any associated abnormalities.

In more severe cases, long-term complications may include problems with speaking and the ability to eat and drink by mouth. 

Why Texas Children’s Fetal Center®?

• A single location for expert maternal, fetal and pediatric care. At Texas Children’s Hospital, you and your baby can get the specialized care required for the treatment of CHAOS all in one location, avoiding the need to transport a critically ill newborn and providing you immediate, easy access to your baby in our renowned NICU. Texas Children’s Hospital is home to the first neonatal intensive care unit to be designated by the Texas Department of State Health Services (DSHS) as a level IV NICU, the highest level of care available for premature and critically ill newborns.
• A skilled, experienced team with proven outcomes. We have a dedicated team of maternal-fetal medicine specialists, surgeons, neonatologists, cardiologists, ECMO specialists, anesthesiologists and others who work in concert to care for you and your baby every step of the way, using protocols we’ve developed over the years that result in excellent, published outcomes. With their combined expertise and unified approach, these leading physicians offer the best possible care for babies with rare birth defects such as CHAOS.
• We offer care for your child’s needs at every stage of life. Our comprehensive approach starts with your first prenatal visit for CHAOS and continues throughout your child’s delivery, postnatal care, and into adolescence, thanks to one of the nation’s leading teams of specialists for the treatment of fetal birth defects.

Volumes & Outcomes – EXIT Procedure

View data on our experience and outcomes with EXIT procedures