Diagnostic utility of ultrasonography for respiratory distress syndrome in neonates

Respiratory distress syndrome (RDS) is the most frequent cause of respiratory failure treated in the neonatal intensive care unit (NICU). The diagnosis is usually based on clinical manifestation and chest X-ray. The aim of the study was to investigate the possible role of chest ultrasound in the diagnosis of the RDS. Ultrasound examination was performed in 131 consecutive newborns admitted to the NICU in their first day of life with symptoms of respiratory failure. The method of ultrasound examination of the chest is based on the "mirror reflection" phenomenon arising on the pulmonary-diaphragmatic border. Retrohepatic or retrosplenic hyperechogenicity was shown in 109 of the 131 examined newborns and the diagnosis was confirmed by X-ray in 101 cases. RDS was diagnosed in no patient without retrohepatic or retrosplenic hyperechogenicity. In eight patients with positive ultrasound images unconfirmed by chest X-ray, congenital pneumonia (four cases) and pneumothorax (one case) were diagnosed and in three cases no pathology was found. The ultrasound examination is characterized by 100% sensitivity and 92% specificity in RDS. There was a strong positive correlation between ultrasound and X-ray imaging in the description of RDS severity (tau = 0.835; p < 0.001). Ultrasound examination cannot replace chest X-ray in the respiratory failure work-up as it overestimates the diagnosis, but it can be useful in excluding RDS as a cause of respiratory insufficiency in newborns.