The 'double lung point': an ultrasound sign diagnostic of transient tachypnea of the newborn.

BACKGROUND: Transient tachypnea of the newborn (TTN) is a mild form of neonatal respiratory distress which early in its course needs to be differentiated from other severe respiratory disorders. At present the diagnosis is based on radiological findings and clinical course. Lung sonography in TTN has not yet been assessed.

OBJECTIVES: The aim of the study was to define the ultrasonographic appearance of TTN and evaluate its clinical relevance.

METHODS: Lung sonography was performed in 32 newborn infants with radiological and clinical signs of TTN within the first hour after birth and the findings were compared with those of 60 normal infants, 29 with respiratory distress syndrome, 6 with pneumonia, 5 with pulmonary hemorrhage and 5 with atelectasis.

RESULTS: In the infants with TTN, lung sonography showed a difference in lung echogenicity between the upper and lower lung areas. There were very compact comet-tail artifacts in the inferior fields while these were rare in the superior fields. We designated this finding the 'double lung point' and it was not observed in healthy infants, infants with respiratory distress syndrome, actelectasis, pneumothorax, pneumonia, or pulmonary hemorrhage. Sensitivity and specificity of the double lung point was 100% for the diagnosis of TTN.

CONCLUSION: We found lung sonography reliable for the early diagnosis of TTN. We suggest that it should become the first approach for imaging of neonatal respiratory distress although further prospective studies with good blinding need to be performed.