Thoracic Ultrasound (TUS) in iatrogenic pneumothorax detection: an easy and reliable tool.

<bold>Background:</bold> Pneumothorax (PNX) is a well-known potential complication of transbronchial biopsy (TBB) and percutaneous transthoracic lung biopsy (PTLB). TUS has been proven efficient in diagnosing post-procedural PNX when performed by trained radiologist/pulmonologist. Nonetheless, it still plays a marginal role in routine post-procedural monitoring. <bold>Aims:</bold> To assess the accuracy of TUS performed by 2 TUS-naive pulmonologists in diagnosing post-interventional PNX compared to Chest X-ray(CXR). To validate a reproducible method to evaluate PNX extension by TUS. <bold>Methods:</bold> Patients who underwent either TBB or PTLB from April 2023 to January 2024 were included. After 2 hours of clinical monitoring, systematic TUS was performed before CXR. <bold>Results:</bold> Of the 96 patients, 30 had undiagnosed interstitial lung disease, 47 had nodules/consolidations and 19 had lung transplants monitoring. PNX was detected by CXR in 16/96 (16,7%), 12 after PTLB, 4 after TBB. Sensitivity, specificity, negative predictive value and accuracy of TUS were 75%, 100%, 95% and 96% respectively. TUS failed to detect PNX in 4 patients. Among them 3 were asymptomatic with PNX <1 cm. Three had an inferior lobe biopsy (75% vs 33% in the true positive group). None required chest drainage placement. PNX extension was correctly quantified in 75% (9/12). <bold>Conclusions:</bold> TUS, even when performed by untrained operators, is an easy and reliable method for detecting and quantifying iatrogenic PNX from different interventional procedures. Moreover, TUS combined with careful clinical evaluation may avoid systematic performance of CXR after procedures with a potential exception, the inferior lobe biopsies.