Ultrasound of pneumothorax in neonates: Diagnostic value of the anterior transverse plane and of mirrored ribs.

Introduction: Point-of-care lung ultrasound is increasingly used to diagnose pneumothorax efficiently and safely in neonates.

Objectives: This study aimed to evaluate the usefulness of the central and anterior transverse thoracic plane in the ultrasound diagnosis of pneumothorax, analyze the diagnostic value of the "mirrored ribs" sign, and evaluate the predictive value of the lung point location for the need of pleural drainage.

Methods: Retrospective cohort study of all newborns admitted to the neonatal intensive care unit of the Basurto University Hospital (Bilbao, Spain) due to respiratory distress and with ultrasound, with or without pneumothorax, between January 2014 and December 2020.

Results: The presence of A-lines behind the sternum in the anterior transverse plane in newborns with pneumothorax (N = 311) and controls (N = 195) was compared. A-lines were present in 98.9% of newborns with pneumothorax compared to none in the controls (p < .0001). Diagnosis of pneumothorax with the anterior transverse plane presented high interobserver reproducibility (κ = 0.92, 95% confidence interval: 0.84-1.00). In contrast, the "mirrored ribs" sign in the anterior longitudinal plane was observed in 35.6% of patients with pneumothorax and in 36.9% of controls (p = .1505). A significant association was observed between lung point location and the need for pleural drainage (p < .0001).

Conclusions: A-lines in the anterior transverse plane is a simple ultrasound sign which presents high sensitivity, specificity, and reproducibility for the diagnosis of pneumothorax. The mirrored ribs sign showed low diagnostic utility. Patients with severe pneumothorax in lung ultrasound are most likely to require thoracic drainage.