Congenital High Airway Obstruction Syndrome (CHAOS)

Congenital high airway obstruction syndrome is characterized by a blockage in a developing baby’s airway.   

A type of fetal lung lesion, congenital high airway obstruction syndrome (CHAOS) occurs when a blockage develops in a baby’s airway while it is still in the mother’s womb. This blockage can affect multiple parts of the fetal airway, including the larynx (voice box) and trachea (windpipe). An obstructed airway prevents the lung fluids from properly draining through the baby’s mouth, potentially leading to congestive heart failure due to increased pressure in the body.

CHAOS is an exceptionally rare condition, with fewer than 50 reported cases since 1989. Recent advancements in medical imaging and fetal care have improved outlooks for babies with CHAOS, although timely treatment is key to a positive outcome.

CHAOS Causes

The root cause of congenital high airway obstruction syndrome is not clear, although it may be related to genetic or chromosomal disorders in some cases. Broadly speaking, CHAOS occurs when the trachea or larynx is obstructed or absent, possibly as a result of:

  • Laryngeal or tracheal atresia (partial development)
  • Tracheal stenosis (narrowing)
  • Tracheal agenesis (absence)
  • A fluid-filled cyst in the airway
  • A thin membrane blocking the larynx or trachea

CHAOS Symptoms

A routine pregnancy ultrasound can display fetal abnormalities that may indicate congenital high airway obstruction syndrome, such as:

  • Significantly enlarged lungs
  • Fluid collecting in the abdomen
  • A compressed diaphragm
  • A widened tracheobronchial tree
  • Indicators of fetal heart failure resulting from severe airway obstruction

Because CHAOS is so uncommon, this condition is sometimes initially misdiagnosed as congenital cystic adenomatoid malformation (CCAM), a condition in which a mass of abnormal lung tissue grows in the chest.

CHAOS Diagnosis

Diagnosing CHAOS often involves multiple approaches, including:

  • Amniocentesis to check for abnormalities in chromosomes
  • A fetal ultrasound or MRI scan to get a closer look at the baby’s airway
  • A fetal echocardiogram to evaluate heart function

CHAOS Treatments

Tampa General Hospital’s Women’s Institute is equipped with the specialized expertise and technology to provide world-class, high-risk obstetrics care to babies with congenital high airway obstruction syndrome and other complex fetal conditions. In life-threatening cases prior to 30 weeks of gestation, treatment for CHAOS may involve open fetal surgery to remove airway blockages. After 30 weeks, a specialized delivery known as the EXIT procedure can be performed under general anesthesia to help the baby breathe immediately after birth.