Limited utility of chest radiograph after thoracentesis

STUDY OBJECTIVE: To assess the utility of chest radiograph (CXR) immediately after routine thoracentesis. DESIGN: Prospective cohort study. SETTING: Multispecialty clinic/teaching hospital. PARTICIPANTS: All outpatients and inpatients undergoing thoracentesis in the procedure area from October 1995 to January 1998. MEASUREMENTS: Immediately after thoracentesis, the physician completed a questionnaire assessing the likelihood of a complication. CXRs were obtained at physician discretion. Patient demographics, indications for thoracentesis, use of ultrasound guidance, level of training, radiographic interpretation, and eventual patient outcome were recorded. RESULTS: Two hundred eighteen patients were enrolled for a total of 278 thoracenteses. Two hundred fifty-one procedures performed on 199 patients could be prospectively evaluated. A complication was suspected in 30 procedures; immediate CXR confirmed such in 9 (30%). There were 221 procedures with no clinical suspicion or indication of a complication. Ninety CXRs were obtained immediately after the procedure; the remaining 131 procedures had no CXR. The complication rates were 3.3% and 2.3%, respectively, for these groups. Four postthoracentesis radiographs demonstrated additional findings regardless of the indication for the radiograph. CONCLUSIONS: In the absence of a clinical indication of a complication, chest radiography is not indicated immediately after routine thoracentesis. Aspiration of air strongly correlates with the occurrence of pneumothorax, whereas pain, hypotension, and dry tap do not. Use of a vacuum bottle to withdraw fluid obscures the appreciation of this finding and was identified as a risk factor for subsequent pneumothorax. Additional radiographic findings are rarely detected and may not contribute to clinical management.