Thoracocentesis for Potential Malignancy: Does Volume Matter?

Full Article

O Buckley, W Benfayed, T Geoghegan, T Persaud, M Jeffers, F Khosa, WC Torreggiani

Hong Kong J Radiol 2008;11:72-5

Objective: To determine whether the volume of fluid aspirated during ultrasound-guided thoracocentesis influences the histological diagnosis.

Methods: Fifty patients with unilateral pleural effusion of unknown cause, in whom malignancy needed to be excluded, were enrolled in this prospective study. Patients had unresolved effusion despite adequate antibiotic therapy, effusion without signs of sepsis or heart failure, or effusion in conjunction with a clinical history suggestive of malignancy (smoking, cough, weight loss, or haemoptysis). Pleural effusions were detected on the basis of clinical examination and plain film chest radiography, and were confirmed by ultrasound. All patients underwent ultrasoundguided thoracocentesis using a 21 G spinal needle and 2 samples of pleural fluid were obtained — a 10-mL aliquot followed by a 50-mL volume sample. The fluid samples were evaluated separately for malignant cells.

Results: Forty seven procedures yielded 2 sufficient volume amounts for analysis. Of the 47 patients included for analysis, 7 had malignancy. The diagnosis of malignancy was separately made on both sample volumes for all 7 patients. The cytological subtype was identical in both samples. There was statistically significant agreement between the 2 volumes for all patients (p < 0.0001). No complications were encountered.

Conclusion: Aspiration of 50 mL of pleural fluid did not confer any advantage over 10 mL of pleural fluid traditionally used for the diagnosis of malignant pleural effusion.