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Abstract

Objective: The primary objective of this study was to report the diagnosticoutcome of all pleural effusions and compare the etiology of large and massiveeffusions. The secondary objective was to compare the biochemicalcharacteristics of different sizes of effusions, in relation to diagnostic outcome.Design: Retrospective chart review of all patients undergoing thoracentesis atSaidu teaching Hospital Saidu Sharif, during five years period.Methods: The size of the effusion was assessed on the postero anteriorradiograph by visually estimating the area of the hemithorax occupied by pleuralfluid. Diagnostic thoracentesis report was available on all the cases that includedRBC count, leukocyte count, percentage of neutrophils, lymphocytes andcytology. Biochemical tests included, glucose level, protein level, lactatedehydrogenase (LDH) level, pH, fluid/serum protein ratio, and fluid/serum LDHratio. Pleural biopsies were performed on selected cases.Results: Among 388 screened cases of pleural effusion 108 had eitherlarge or massive effusion and 280 cases had non- large effusion. Large pleuraleffusions (two thirds or more of the hemi thorax) were found in 68 cases andmassive effusions (entire hemi thorax) in 40 cases. There was a similar etiological spectrum between large and massive pleural effusion. The most frequent cause of these pleural effusions was tuberculosis; in 40 patients (37%) followed by malignancy in 31 (29%), and complicated parapneumonic effusion in 19 patients (18%). Among massive effusions, malignancy was most frequent (15 patients: 38%). Compared with nonmalignant pleural effusions, patients with large or massive malignant pleural effusions were more likely to have pleural fluids with higher RBC counts (18.0 cells/L vs. 2.7 10 cells/L, respectively; p < 0.001). Compared with non-large effusions, large and massive malignant pleural effusions showed higher median RBC counts (18.0×10 cells/L vs. 4.3×10 cells/L, respectively; p < 0.001), higher lactate dehydrogenase levels (641 vs. 409 U/L, respectively; p 0.001), lower pH (7.39 vs. 7.42, respectively; p 0.006)Conclusions:The presence of a large or massive pleural effusion enables the clinician to narrow the differential diagnosis of pleurisy, since most effusions are secondary to malignancy or infections (either bacterial or mycobacterial). Bloody pleural fluid are likely to favor malignancy.