PRENATAL-DIAGNOSIS OF LARYNGEAL ATRESIA IN 2 CASES OF CONGENITAL HIGHAIRWAY-OBSTRUCTION SYNDROME (CHAOS)

Complete occlusion of the upper airways is known to cause secondary mo rphological changes, including bilaterally enlarged hyperechogenic lun gs, dilated trachea, and hydrops. Prenatal diagnosis of upper airway o bstruction has been described in several cases. In these reports, the diagnosis was primarily attributed to indirect signs, and the authors were in doubt as to whether the location of the obstructed area (laryn x, glottis or trachea) could be precisely visualized by ultrasound. In this paper two cases are reported presenting the features of congenit al high airway obstruction syndrome (CHAOS) diagnosed at the 22nd week of gestation. In both cases, the upper neck was perfectly visualized in a coronal plane. At the onset of fetal breathing movements, the ste notic larynx remained in a closed position. By positioning a colour si gnal on the fluid-filled dilated trachea, we noticed absence of flow t hroughout the onset of breathing activity. We conclude that the atreti c area must be situated at the level of the larynx. Because of the poo r prognosis of laryngeal stenosis and the presence of associated anoma lies, both pregnancies were terminated in the 23rd week. This report s hows that the application of colour and spectral Doppler may be helpfu l in the differential diagnosis of fetuses with CHAOS. (C) 1997 by Joh n Wiley & Sons, Ltd.