Introduction: The purpose of this study is to determine how long patients who developed pneumothorax were followed up on in the emergency department, how many patients required chest tube placement, and what factors influenced the need for a chest tube in patients who underwent computed tomography (CT)-guided percutaneous trans -thoracic fine needle aspiration biopsy (PTFNAB).Materials and Methods: Patients who developed pneumothorax following CT-guided PTFNAB were analyzed retrospectively. In cases with pneumotho-rax, the relationship between chest tube placement and the size of the lesion, the lesion depth from the pleural surface, the presence of emphysema, and the needle entry angle were investigated. It was determined how long the patients were followed up in the emergency department, when a chest tube was pla-ced, and when patients who did not require chest tube placement were discharged.Results: CT-guided PTFNAB was performed in 3426 patients within two years. Pneumothorax developed in 314 (9%) cases and a chest tube was placed in 117 (37%). The risk factor for chest tube placement was found to be the lesion depth from the pleural surface. The lesion depth from the pleural surface of >24 mm increased the risk of chest tube placement by 4.8 times. Chest tubes were placed at an average of five hours (5.04 +/- 5.57).Conclusion: This study has shown that in cases with pneumothorax that required chest tube placement, the lesion depth from the pleural surface is a risk factor. Patients who developed pneumothorax on CT during the procedure had chest tubes placed after an average of five hours
