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Lung | Congenital high airway obstruction (CHAOS)

Congenital high airway obstruction (CHAOS) is a blockage in the upper airway of the fetus.

This condition can be identified on a routine pregnancy ultrasound. Once identified, the pregnancy will be closely monitored, and fetal surgery may be necessary.

Severe cases (where there is complete airway obstruction) may result in fetal heart failure and intrauterine death.

Essential Information

  • In cases of CHAOS, the pregnancy is monitored very carefully.
  • Tests may be done to help understand the cause of the blockage and whether other conditions are present.
  • The baby may need to be delivered early by caesarean section, and urgent surgery may be necessary at birth to help the baby breathe.
  • CHAOS can be life-threatening to the fetus or neonate.


When CHAOS has been identified, tests will be done to reveal the cause and whether any other conditions are present. These tests may include a detailed ultrasound, a fetal echocardiogram to check the baby’s heart, a CT scan, and an amniocentesis to rule out chromosomal anomalies.

When a fetus has a compromised airway, there is a concern that it may not be able to breathe at delivery. The inability to secure its airway quickly can result in death or brain damage due to a lack of oxygen. In the most severely affected cases, surgical intervention may be necessary either during pregnancy, at birth, or after the birth. The timing of such interventions will depend on the exact cause of the airway obstruction and the anticipated difficulty in establishing an airway at birth.

Fetal ultrasound and MRI can differentiate the types of airway obstruction, which allows for optimal planning and management of the delivery and neonatal resuscitation.


A procedure called an EXIT (ex-utero intra-partum treatment) may be necessary. This is a birth by a modified caesarean section in which the baby’s airway is safely established while the baby is still connected to the placenta. A neonatal airway must be established quickly to avoid brain damage due to a lack of oxygen.

A successful EXIT delivery requires a highly trained, well co-ordinated, multidisciplinary team in a hospital setting.

Referral Information

All patients with CHAOS should be referred to a tertiary care centre, such as Mount Sinai Hospital, for evaluation.