Unusual new signs of pneumothorax at lung ultrasound

BACKGROUND The diagnosis of pneumothorax with a bedside lung ultrasound is a powerful methodology. The conventional lung ultrasound examination consists of a step-by-step procedure targeted towards the detection of four classic ultrasound signs, the lung sliding, the B lines, the lung point and the lung pulse. In most cases, a combination of these signs allows a safe diagnosis of pneumothorax. However, the widespread application of sonographic methodology in clinical practice has brought out unusual cases which raise new sonographic signs. The purpose of this article was to introduce some of these new signs that are described after the analysis of unusual and complex cases encountered during the clinical daily practice in an emergency department. FINDINGS The double lung point consists of the alternating patterns of sliding and non-sliding lung intermittently appearing at the two opposite sides of the scan. The septate pneumothorax allows B lines and lung pulse to be still visible in a condition of pneumothorax with absent sliding. In hydropneumothorax, the air/fluid border is imaged by lung ultrasound as the interposition between an anechoic space and a non-sliding A-pattern, a sign that may be named hydro-point. CONCLUSIONS In bedside lung ultrasound, the operator should be aware and interpret double lung point, septate pneumothorax and hydro-point. The conventional diagnostic protocol of bedside lung ultrasound for pneumothorax should be occasionally adapted to such complex cases.