Congenital High Airway Obstruction (CHAOS)

Congenital High Airway Obstruction Syndrome (CHAOS) is a rare condition due to blockage of the baby’s upper airway. This is a severe life-threatening condition that may involve the trachea (windpipe) or larynx (voice box). The obstruction may be complete or partial due to either a web-like membrane, narrowing of the airway (stenosis), or absence of the trachea or larynx (tracheal or laryngeal atresia).

The cause of CHAOS is unknown. Some babies may also have other birth defects, therefore it is important to evaluate for this during the regular prenatal scan as well as an additional ultrasound called echocardiogram to assess the baby’s heart structure and function.

Additionally, genetic testing of the baby’s chromosomes is available because there is an association of certain genetic problems with CHAOS. This testing is performed by sampling fluid from around the baby (amniocentesis).

Because of the additional birth defects and/or genetic problems associated with CHAOS, pregnancies with CHAOS are seen within our Fetal Diagnosis and Treatment Center where our multidisciplinary team can evaluate, diagnose, and treat you and your baby.  Your comprehensive evaluation would entail:

  • Ultrasound unit to define the airway anatomy and look for other abnormalities
  • Consultation with our Maternal-Fetal Medicine team
  • Consultation with our genetic counselors. This would include discussion of amniocentesis for karyotype and/or microarray to test the fetal chromosomes.
  • Fetal echocardiogram to assess heart structure and function
  • Fetal MRI to assist in determining the location of the airway obstruction
  • Consultation with our Pediatric Surgery and/or Pediatric Otolaryngology (ENT) team(s)

How does CHAOS affect my baby in-utero?

Normally, fetal lungs continuously produce fluid. With normal airway anatomy, the fluid can leave the baby and enter the amniotic sac. However, when there is a blockage like CHAOS, the lung fluid cannot leave the baby. The lungs become congested with fluid, appearing enlarged and very bright on prenatal ultrasound. This causes the airways to enlarge, putting pressure on the baby’s breathing muscle (diaphragm), and causes the diaphragm to be flattened or curved downward. This may also put pressure on the heart, making it harder to function normally and/or leading to heart failure.  This may result in swelling or accumulation of excess fluid (non-immune hydrops) in your baby. This extra fluid can be seen in the belly, chest, and skin.

How does CHAOS affect my baby after birth?

When a baby is born after an uncomplicated pregnancy, he or she takes the first breaths through the airway and into the lungs, and this provides crucial oxygen to the baby’s brain and body.  If a baby is born before a diagnosis of CHAOS is known, it usually results in death after delivery due to lack of oxygen. Fortunately, most cases can be detected in-utero, allowing for timely diagnosis, multidisciplinary collaboration, and careful delivery planning.

To provide an open airway so that oxygen can be delivered to your baby, we recommend your baby be delivered via an EXIT (Ex Utero Intrapartum Treatment) procedure. This is used in situations in which there is a known airway blockage in the baby. The goal of the procedure is to do a Cesarean delivery and partially deliver the baby’s head and neck from the uterus while the baby remains attached to the placenta and mother. While the placenta continues to deliver necessary oxygen through the baby’s umbilical cord, our team can place a camera through the baby’s mouth to look into the airway and/or place an airway tube. If an airway tube cannot be placed through the mouth, the team creates an airway for the baby by making an incision in the neck and placing an airway tube directly into the windpipe (trachea) below the blockage so that oxygen can fill the lungs. In this way, your baby is not deprived of oxygen and minimizes the chance of damage to the baby’s brain and other organs.

An EXIT procedure involves many teams including maternal anesthesia specialists, Maternal-Fetal Medicine and pediatric surgeons, pediatric otolaryngologists (ENT), and neonatologists. After an airway is safely obtained and your baby has been stabilized, your baby will be brought to the Neonatal Intensive Care Unit (NICU) which is located under same roof as Labor and Delivery where you would recover from your Cesarean delivery.  Additional evaluation and surgeries may be required while your baby is in the NICU.

What is the outcome after CHAOS treatment?

The outcome for a baby with CHAOS depends on many factors. The location and type of airway blockage, gestational age when CHAOS is diagnosed, and how sick a baby is while in utero are all factors which impact the care needed to treat CHAOS and overall survival. If there is early body swelling (hydrops), opportunities to treat a baby after delivery may be limited. Early delivery of a very sick newborn sometimes creates more problems for the baby and is not always a beneficial strategy. Finally, if there are other abnormalities or associated genetic problems, this may also affect the outcome and interventions available to help your baby.  

Once your baby is born, our teams work together to best understand what caused the blockage in the trachea. If the obstruction is more minor (such as a thin tissue membrane covering the larynx) it may be treated with minimal surgery after birth. However, it is more serious if the obstruction occurred due to a complete blockage of the larynx or a missing section of trachea.  Babies born with this problem will not be able to breathe independently when they are born. These babies require placement of a breathing tube through the neck (tracheostomy). Multiple operations will be needed to repair the airway, a process which may take years. Because of the relationship between the trachea and the vocal cords, there may also be problems with how the voice functions as well.

Our team of experts is ready to help your family through this journey. We have extensive experience caring for pregnancies complicated by CHAOS and are prepared to help you through each step of this process.

Make an Appointment

If you have questions or would like to schedule an appointment with the Fetal Diagnosis & Treatment Center, please call 734-763-4264.