Congenital high airways obstruction syndrome (CHAOS) refers to a rare, often lethal, congenital laryngotracheal condition and is primarily characterized by obstruction to the fetal upper airway.
CHAOS can be of three possible types 2:
- complete laryngeal atresia without an esophageal fistula
- complete laryngeal atresia with a tracheo-esophageal fistula
- near-complete high upper airway obstruction
Ultrasound may show some or all of the following features 4,5
- 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
May confirm features detected on ultrasound as well as more accurately show the level of obstruction. Lung signal is increased 5.
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 1,3. Overall prognosis is considered generally poor 6.
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- 2. Hartnick CJ, Rutter M, Lang F et-al. Congenital high airway obstruction syndrome and airway reconstruction: an evolving paradigm. Arch. Otolaryngol. Head Neck Surg. 2002;128 (5): 567-70. Arch. Otolaryngol. Head Neck Surg. (link) - Pubmed citation
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- 4. Mong A, Johnson AM, Kramer SS et-al. Congenital high airway obstruction syndrome: MR/US findings, effect on management, and outcome. Pediatr Radiol. 2008;38 (11): 1171-9. doi:10.1007/s00247-008-0962-2 - Pubmed citation
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- 7. Kuwashima S, Kitajima K, Kaji Y et-al. MR imaging appearance of laryngeal atresia (congenital high airway obstruction syndrome): unique course in a fetus. Pediatr Radiol. 2008;38 (3): 344-7. doi:10.1007/s00247-007-0693-9 - Pubmed citation
- 8. Biyyam DR, Chapman T, Ferguson MR et-al. Congenital lung abnormalities: embryologic features, prenatal diagnosis, and postnatal radiologic-pathologic correlation. Radiographics. 2010;30 (6): 1721-38. doi:10.1148/rg.306105508 - Pubmed citation