Pleural effusion Investigation Clinical history Elicit an accurate drug history as part of the initial clinical assessment of patients with pleural effusion. E Diagnostic thoracentesis Q Does the patient have bilateral pleural effusions? Q Does the clinical setting strongly suggest a transudate? Yes to all Avoid performing diagnostic thoracentesis in patients with bilateral pleural effusions in a clinical setting strongly suggestive of a transudate, unless there are atypical features, or effusions fail to respond to therapy. D No to any Perform a diagnostic thoracentesis to obtain a diagnostic pleural fluid sample, using a fine-bore (21G) needle and a 50 mL syringe. E Use bedside U/S guidance for diagnostic thoracentesis. B Record the appearance and odour (if any) of the pleural fluid. E Pleural fluid analysis Use Light's criteria to distinguish between a pleural fluid exudate and transudate. B Send pleural fluid for protein, LDH, Gram stain, cytology and microbiological culture. B Obtain pleural fluid pH in non-purulent effusions when pleural infection is suspected. B Consider obtaining pleural fluid hematocrit to assess for hemothorax. E Thoracoscopic biopsy Q Is pleural aspiration inconclusive and malignancy suspected? Yes Perform thoracoscopy in patients with an exudative pleural effusion in whom malignancy is suspected, when diagnostic pleural aspiration results are inconclusive. B No Chest CT Q Is there an undiagnosed exudative pleural effusion? Q Is there a need to distinguish malignant from benign pleural thickening? Q Is there complicated pleural infection when initial tube drainage has been unsuccessful and surgery is to be considered? Yes to any Obtain a CT scan of the chest in all patients with undiagnosed exudative pleural effusions. CT can assist in distinguishing malignant from benign pleural thickening. B Perform CT scan of the chest with the administration of intravenous contrast, and before complete drainage of pleural fluid. B No to all Blood cultures Q Does the patient have suspected pleural infection? Yes Obtain blood cultures for aerobic and anaerobic bacteria in all patients with suspected pleural infection. B No Diagnostic bronchoscopy Q Is there hemoptysis or clinical or radiographic features suggestive of bronchial obstruction? Yes Avoid routine diagnostic bronchoscopy in the evaluation of undiagnosed pleural effusion. D Consider bronchoscopy if there is hemoptysis or clinical or radiographic features suggestive of bronchial obstruction. C No Percutaneous pleural biopsy Q Is there an undiagnosed effusion where malignancy is suspected and areas of pleural nodularity are shown on contrast-enhanced CT? Yes Perform an image-guided cutting needle percutaneous pleural biopsy in patiens with an undiagnosed effusion where malignancy is suspected, and areas of pleural nodularity are demonstrated on contrast-enhanced CT. A No Chest tube drainage Q Does the patient have frankly purulent or turbid/cloudy pleural fluid on sampling? Q Is the presence of organisms identified by Gram stain and/or culture from a non- purulent pleural fluid sample? Q Is the pleural fluid pH <7.2 in patients with suspected pleural infection? Q Is there poor clinical progress during treatment with antibiotics alone? Q Does the patient have a loculated pleural collection? Q Is there large non-purulent effusions? Yes to any Perform chest tube drainage promptly in patients with pleural effusions in whom frankly purulent or cloudy pleural fluid is obtained upon thoracentesis. B Perform chest tube drainage promptly in patients with organisms identified by Gram stain and/or culture from a non-purulent pleural fluid sample. B Perform chest tube drainage in patients with pleural fluid pH < 7.2 and suspected pleural infection. B Perform chest tube drainage in patients with a loculated pleural collection. B Consider chest tube drainage in patients with inadequate response to antibiotic treatment alone, with repeat pleural fluid sampling. C No to all Patients with suspected pleural tuberculosis Q Does the patient have suspected pleural TB? Yes Thoracoscopic pleural biopsies are the test most likely to yield positive mycobacterial culture (and therefore drug sensitivity) results. B Surrogate markers of pleural TB are useful rule out' tests in low incidence countries. Adenosine deaminase is the most thoroughly validated to date. B No Pleural fluid cytology Q Is there a suspicion of malignant effusions? Yes Malignant effusions can be diagnosed by pleural fluid cytology in about 60% of cases. B The yield from sending more than two specimens (taken on different occasions) is very low and should be avoided. B No Patients with chylothorax Q Is there a suspicion of chylothorax or pseudochylothorax? Yes Obtain pleural fluid triglyceride and cholesterol levels in patients with suspected chylothorax or pseudochylothorax, and test pleural fluid for cholesterol crystals and chylomicrons. B No Continue management as clinically appropriate.