What is Congenital High Airway Obstruction Syndrome (CHAOS)?
Congenital high airway obstruction syndrome (CHAOS) is a condition diagnosed in the fetus and characterized by several abnormalities due to the airway being completely obstructed. The obstruction may be due to a cyst or web in the larynx (the voice box in the upper part of airway, below the throat) or to atresia (complete blockage) of the larynx or of the trachea (the continuation of the airway below the larynx and before dividing into the bronchial trees within the lungs). Regardless of the cause, the results are massive enlargement of the lungs and dilation of the bronchial trees, a flattened or inverted diaphragm (the partition between the chest and abdominal areas), a large amount of fluid in the abdomen (ascites), and other signs of in utero heart failure (nonimmune hydrops or extensive swelling), all due to obstruction of the fetal airway. Most fetuses diagnosed with CHAOS associated with hydrops do not survive, unless there is spontaneous perforation of the atresia that is causi
