Testing & Diagnosis for Congenital High Airway Obstruction (CHAOS) in Children

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How is congenital high airway obstruction diagnosed?

CHAOS is first detected on prenatal ultrasound. If your doctor suspects a problem, you will be referred to a doctor who specializes in high-risk cases for a more detailed ultrasound.

What signs will my doctors look for in the ultrasound?

The main signs are swollen and elongated trachea and bronchial tubes. This swelling happens as a result of a build-up of fluid normally expelled through the trachea with fetal breathing movements.

In more advanced cases, doctors may notice the following:

  • signs of impending heart failure (hydrops)
  • polyhydramnios (excess amniotic fluid)
  • ascites (accumulation of fluid in the abdominal cavity)

The fetus may also appear to have abnormal breathing movements.

Will my doctor order any other tests?

Your doctor may decide that you should have an MRI (Magnetic Resonance Imaging) of your abdomen to get better pictures of the fetus and to determine what's causing the obstruction, whether it's a cyst in the larynx or atresia either of the larynx or trachea.

MRI may be necessary to rule out other conditions that resemble CHAOS, particularly cystic adenomatoid malformation (CCAM).

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