Frequency and characteristics of pleural effusions in pulmonary embolism

Pulmonary embolism (PE) is the fourth cause of pleural effusions, after pneumonia, neoinfiltrates and tuberculosis. Several questions are yet unanswered: are the pleural effusions in PE exudates or transudates, what is their size, are they unilateral or bilateral, are they only haemorrhagic, etc. The aim of this study is to determine the frequency, side, size, biochemical and cytological characteristics of pleural effusions in PE. In this study, 100 patients with suspicion of PE were examined and treated and in all the diagnosis of PE was establish. 31 of them had pleural effusions. Of 31 patients with PE and pleural effusions, six (9.84%), had bilateral pleural effusions, 14 (22.95%) patients had right-sided pleural effusion, and 11 (18.03%) had pleural effusion on the left side. 22 (36.07%) had small pleural effusions, 8 (13.11%) had medium and 1 (1.64%) had a large pleural effusion.18 (29.51%) had yellowish colored pleural effusions, 12 (19.67%) had haemorrhagic pleural effusions and 1 (1.64%) had transparent pleural effusion. Values of the total protein in pleural effusions varied in the interval 45.70±7.25 gr/l., 30 patients had LDH an effusion/sera ratio bigger than 0.6, and 1 patient had an LDH p/s ratio<0.6. 15 patients (24.59) had neutrophil cells, 10 (16.39%) had lymphocytes, and eosinophil cells dominated in 5 (8.20%). One patient (1.64%) had a negative cytological finding. We can conclude that pleural effusions secondary to PE can be found in around one third of all cases with PE. They are small, mostly unilateral, often but not always haemorrhagic. They are always exudates with a predomination of neutrofil cells.