Congenital high airway obstruction syndrome
Congenital high airway obstruction syndrome or sequence (CHAOS) refers to a rare, often lethal, congenital laryngotracheal condition and is primarily characterized by obstruction to the fetal upper airway.
Pathology
CHAOS can be of three possible types :
- complete laryngeal atresia without an esophageal fistula
- complete laryngeal atresia with a tracheo-esophageal fistula
- near-complete high upper airway obstruction
Associations
Radiographic features
Antenatal ultrasound
Ultrasound may show some or all of the following features
- dilated trachea/bronchi: distal to the obstruction
- enlarged and echogenic lungs
- diaphragmatic inversion and/or flattening
- presence of fetal ascites
- the fetal heart may appear displaced to the midline and compressed
Ancillary sonographic features include
- presence of fetal anasarca
- presence of polyhydramnios
Fetal MRl
May confirm features detected on ultrasound as well as more accurately show the level of obstruction. Lung signal is increased .
Treatment and prognosis
The prenatal natural history and postnatal course of CHAOS often depends on whether the airway obstruction is complete. An ex utero intrapartum treatment (EXIT) procedure may offer potential for salvage . Overall prognosis is considered generally poor .
Differential diagnosis
The differential diagnosis of echogenic fetal lung is congenital cystic adenomatoid malformation (CCAM) type III. In CHAOS, both lungs are echogenic, whereas CCAM is usually unilateral, but can be bilateral in rare cases. Dilated airway is another clue which is seen only in CHAOS .
See also
