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.