Evaluation of Intrinsic Fetal Airway Obstruction (CHAOS): Correlations Between Ultrasound, Fetoscopic, and Pathological Findings.

Objective: To correlate ultrasound findings with fetoscopy and pathology data in patients with suspected congenital high airway obstruction syndrome (CHAOS) to improve prenatal diagnosis and management. Method: This study included five consecutive patients suspected of having CHAOS. Prenatal ultrasound was performed to identify key features such as bilateral hyperechoic lungs, eversion of the diaphragm, and visible airways. Fetoscopy was conducted in three patients to assess the vocal cords and upper airways. Pathological analysis was also used to confirm the diagnosis.

Results: All five patients showed bilateral hyperechoic lungs, eversion of the diaphragm, and visible airways on ultrasound. An obstructive block was seen in all cases and the vocal cords were not visualized in three cases, abnormal in one case and not mentioned in one case. Fetoscopy confirmed vocal cord fusion or absence and complete laryngeal atresia in three patients. All pregnancies were terminated; therefore, medium-term complications of fetoscopy could not be assessed.

Conclusion: Accurate prenatal ultrasound imaging is essential for diagnosing CHAOS and determining prognosis. While ultrasound is the first-line test to assess the condition and guide management, fetoscopy should only be proposed when ultrasound findings are inconclusive. The diagnostic and therapeutic value of fetoscopy is limited to cases with nonvisible vocal cords and obstructive laryngeal block.