Congenital high airway obstruction syndrome
Citation, DOI & article data
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.
CHAOS can be of three possible types 2:
complete laryngeal atresia without an 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 echogenic lungs
diaphragmatic inversion and/or flattening
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 depend 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.
The differential diagnosis of echogenic fetal lung is congenital pulmonary airway malformation (CPAM) type III. In CHAOS, both lungs are echogenic, whereas CPAM is usually unilateral, but can be bilateral in rare cases. Dilated airway is another clue that is seen only in CHAOS 9-11.
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- 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
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- 10. Laxmi Devi Padmanabhan, Sheela Nampoothiri. Prenatal detection of congenital high airway obstruction syndrome with encephalocele. (2016) Indian Journal of Radiology and Imaging. 26 (1): 70. doi:10.4103/0971-3026.178336 - Pubmed
- 11. Artunc Ulkumen B, Pala HG, Nese N, Tarhan S, Baytur Y. Prenatal diagnosis of congenital high airway obstruction syndrome: report of two cases and brief review of the literature. (2013) Case reports in obstetrics and gynecology. 2013: 728974. doi:10.1155/2013/728974 - Pubmed