Incidence and risk factors of delayed pneumothorax after transthoracic needle biopsy of the lung.

STUDY OBJECTIVES To evaluate the incidence and clinical significance of delayed pneumothorax, and to analyze the influence of multiple variables on the rate of delayed pneumothorax associated with transthoracic needle biopsy (TTNB) of the lung. STUDY DESIGN Prospective study. SETTING Tertiary care university hospital. STUDY SUBJECTS Adult patients underwent TTNB from June 2001 to June 2002. MEASUREMENTS AND RESULTS Among the 458 patients included in this study, 280 fluoroscopic-guided, 21 CT-guided, and 157 ultrasonography-guided lung biopsies were performed. A follow-up chest radiograph was obtained immediately, and 3 h, 8 h, and 24 h after the biopsy procedure. Pneumothorax that had not developed up to 3 h but developed later was defined as a delayed pneumothorax. Patients with a symptomatic or enlarged pneumothorax were treated using a pigtail catheter or chest tube. Variables such as age, gender, lesion size, location, presence of an emphysematous change, biopsy guidance methods, and biopsy devices were analyzed. Pneumothorax developed in 100 of the 458 patients (21.8%), and delayed pneumothorax developed in 15 patients (3.3%). Seventeen patients, including 3 patients with delayed pneumothorax, required a pigtail catheter or a chest tube insertion. The pigtail catheter or chest tube insertion rate in delayed pneumothorax was 20% (3 of 15 patients). Female gender and the absence of an emphysematous change correlated with an increased rate of delayed pneumothorax (p < 0.05). Lesion size, location, biopsy guidance methods, devices, and underlying diseases were not correlated with the delayed pneumothorax rate. CONCLUSIONS The incidence of delayed pneumothorax was 3.3% of all TTNBs. Female gender and the absence of an emphysematous change were identified as risk factors for delayed pneumothorax. Delayed pneumothorax is clinically important because of its considerable incidence and the necessity for pigtail catheterization or chest tube insertion in these patients.