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Fetal laryngoscopy to evaluate vocal folds in a fetus with congenital high airway obstruction syndrome (CHAOS)

Congenital high airway obstruction syndrome (CHAOS) is a rare fetal condition in which an intrinsic obstruction of the upper airway is present, ranging from a simple airway stenosis to complete agenesis with fused vocal cords1. The general level of obstruction can be readily identified by fetal ultrasound and magnetic resonance imaging (MRI), but determining specific causes and severity of obstruction (e.g. long-segment laryngeal atresia vs a thin membrane) has been a challenge2. We report here the feasibility of using fetal laryngoscopy to evaluate the vocal cords of a fetus with CHAOS. A 46-year-old woman, gravida 3 para 0, was referred at 19 weeks’ gestation with a fetus showing sonographic features of CHAOS. These included a dilated trachea and bronchial tree, as well as bilaterally hyperechoic lungs with significant ascites and inverted diaphragm. There was no hydrops nor associated anomalies. There was no sign of Fraser syndrome. A fetal echocardiogram demonstrated normal anatomy and function with mildly increased cardiac output but no evidence of fetal heart failure. Fetal ultrasound and MRI revealed obstruction at the level of the larynx, with a probable obstructing membrane at the level of the subglottic airway, just below the vocal folds (Figure 1a). The karyotype was normal. The patient and her husband requested information about the condition of the fetal vocal cords and the severity of obstruction. Following multidisciplinary counseling, they elected to undergo fetoscopic diagnostic laryngoscopy to evaluate the anatomy of the larynx and trachea. In the event that the vocal cords were intact and that the obstruction could be relieved, the parents requested that we attempt laser treatment to open the obstructed trachea. The institutional Fetal Therapy Board approved the procedure. At 21 weeks’ gestation, fetoscopic laryngoscopy was performed under maternal sedation with local anesthesia and ultrasound-guided fetal intramuscular anesthesia. Using the same technique as for fetal endoscopic tracheal occlusion, the fetoscope was advanced into the amniotic cavity3. The fetoscope was advanced down the oropharynx until the esophagus was seen. On fetoscopic visualization, the oropharynx, epiglottis, supraglottic structures and esophagus were noted to be normal. However, the vocal cords were fused and no location for laryngeal entry was seen (Figure 1b). An interstitial 400μm laser fiber was advanced until it made contact with the mid-sagittal area of vocal cord fusion, and we attempted to open the obstruction using a diode laser (Multibeam, Dornier Medtech, Kennesaw, GA, USA), in order to evaluate the extent of the atresia. The procedure was abandoned Fused vocal cords Epiglottis