Routine Chest Radiographs after Uncomplicated Thoracentesis

Hospitalists might think routine CXRs are helpful after ultrasound-guided thoracentesis for additional reasons. First, modern guidelines reflecting the low risk of complications after ultrasound-guided procedures have not been released by United States pulmonary medicine societies, and some clinicians may continue to follow practices acquired during the era of unguided thoracentesis. Second, performing postprocedure imaging has become ingrained as a standard part of some institutional procedure checklists⁶ and some prominent textbooks continue to recommend the practice.⁷ For some hospitalists, this testing reflex may be reinforced by other common procedures, such as placing a nasogastric tube or a central venous catheter, for which a postprocedure CXR is standard practice. Thus, ordering postprocedure imaging can become internalized as the safe, checklist-based final step of a procedure. Third, hospitalists may order a postprocedure CXR for reasons other than detecting procedural complications. The pleural effusion might be thought to obscure a parenchymal or endobronchial lesion for which a postprocedure CXR may reveal an important finding. Finally, a CXR also may also satisfy the clinician’s curiosity regarding the completeness of drainage.

A routine post-thoracentesis CXR is not necessary for three reasons. First, the use of ultrasound marking or guidance has substantially improved site selection and reduced the rate of complications for experienced operators. For example, a 2010 systematic review found an overall rate of pneumothorax of 4% for ultrasound-guided procedures performed between 1986 and 2006,³ whereas more recently published data suggest the current rate of pneumothorax is closer to 1% when ultrasound marking or guidance is used.^8,9 One study of 462 consecutive patients with malignant pleural effusions, for example, showed that the rate of pneumothorax with ultrasound-guided needle-over-catheter thoracentesis was 0.97% (3/310 patients), compared with a rate of 8.89% (12/135 patients) when the procedure was performed without ultrasound.⁹ Another prospective, randomized study of 160 patients with various causes of pleural effusion showed that the rate of pneumothorax with ultrasound-marked thoracentesis was 1.25% (1/80 patients), compared with 12.5% (10/80 patients) for procedures performed without ultrasound.⁸ Hospitalists who competently use ultrasound guidance should act on modern estimates of complications and may also choose to incorporate postprocedure ultrasound into their practice. Indeed, the Society of Hospital Medicine recommends against routine chest radiography in asymptomatic patients when sliding lung is visualized on postprocedure ultrasound.¹⁰

Second, procedural factors and postprocedural symptoms (new chest pain, dyspnea, or persistent cough) reliably identify patients with high risk of clinically meaningful complications. On one hand, only 1% to 2% of asymptomatic patients have a postprocedure pneumothorax, and clinical monitoring does not lead to chest tube placement in almost all of these cases.¹¹ On the other hand, 67% to 72% of symptomatic patients are found to have complications.¹² Doyle et al¹³ showed that the use of symptoms and procedure-specific factors (such as the aspiration of air, difficult procedure, multiple needle passes, or high operator suspicion of pneumothorax) could obviate the need for routine CXRs in approximately 60% of their procedures without any serious consequences.

Third, postprocedural CXRs very rarely reveal new or unexpected findings. For example, in one series,¹² only 3.8% of postdrainage radiographs uncovered new findings, none of which clarified the underlying diagnosis or changed management. To assess the utility of an initial thoracentesis and decide about repeat procedures, begin by asking the patient about symptoms and perform a physical exam.