Additional methods of examination

Clinical blood analysis: leukocytosis, neutrophilia, accelerated ESR (during progression of chronic diseases), may be anemia and secondary erythrocytosis;

Sputum analysis: more frequently sputum isn't discharge.

X-ray examination: over the fluid assessed intensive, homogenous darkening with horizontal or slating level.

Pleural fluid analysis. Characteristics of the pleural fluid obtained in thoracentesis may be serous and serofibrinous (exudative pleurisy, rheumatic pleurisy); seropurulent (pneumonia, tuberculosis, exudative pleurisy); purulent (bacterial pleurisy); hemorrhagic (traumatic pleura affection, tuberculosis, infarction or tumor of the lungs); chyleous (congestion of the lymph or destmction of the thoracic duct by a tumor or an injury); cholesterol (chronic in flammation of the serous membrane as a result of cellular degradation with fatty degeneration); putrefactive (lung's gangrene).

Study of the pleural fluid. Analysis of the pleural fluid includes macroscopic, physicochemical, microscopic and sometimes microbiological and biological analysis.

The appearance of the pleural fluid depends mostly on its cell composition and partly on the chemical composition. Fluids of the following character are differentiated: serous, serofibrinous, fibrinous, seropurulent, purulent, putrefactive, haemorrhagic, chylous, and chylous-like.

Transudate and serous effusion are clear and slightly opalescent. Turbidity of the fluid may be due to abundance of leucocytes (seropurulent and purulent effusion), erythrocytes (haemorrhagic effusion), fat drops (chylous effusion) or cell detritus (chylous-like effusion). The character of the cells can be determined by microscopy. The chylous character of the effusion is determined by an ether test (opacity disappears in the presence of ether).

The colour of transudate may be pale yellow, serous effusion from pale yellow to golden, and in jaundice it may be deep yellow. Purulent effusion is greyish or greenish-yellow; in the presence of blood it becomes reddish or, more frequently, greyish-brown. The putrefactive effusion is of the same colour. Depending on the amount of the haemorrhage and also on the time of blood retention in the pleura, the haemorrhagic fluid can be pink to dark red or even brown. In haemolysis it may have the appearance of lacquer. Chylous effusion looks like thin milk.

The consistency of pleural effusion is usually liquid. Purulent fluid can be thick, cream-like, and sometimes it enters the puncture needle with difficulty. Pus of the old encapsulated empyema can be of puree consistency, with grains, and fibrin a flake.

Only putrefactive effusion has offensive smell (gangrene of the lung). The smell depends on protein, which is decomposed by anaerobic enzymes.

Physicochemical studies of the pleural fluid include determination of relative density of the fluid and protein; these are the main criteria for differentiation between the effusion and transudate. Relative density of the pleural fluid is determined by a hydrometer; a urometer is normally used or the purpose. Relative density of the transudate is about 1.015 g/cm³ (1.006-1.012), and of the effusion is slightly higher, i.e. 1.018-1.022.

Protein content is lower in transudate than in the pleural fluid, i.e. not higher than 3 per cent (usually 0.5-2.5 per cent). The pleural effusion contains from 3 to 8 per cent of protein. A refractometric method is more suitable for determining protein in the pleural fluid, but some other methods can also be used, such as biuretic, gravimetric, Roberts-Stolnikov method. The composition of protein fractions of the pleural fluid is about the same as of blood serum, albumins prevail in transudate while fibrinogen is absent or almost absent or which reason transudate does not clot. The fibrinogen content of pleural effusion is lower than that of blood (0.05-0.1 per cent) but its quantity is sufficient to clot spontaneously most of them. The total protein content of transudate rarely reaches 4-5 per cent and additional tests are therefore used to differentiate it from the pleural effusion. Rivalta's reaction: a cylinder is filled with water acidified with a few drops of acetic acid; or 2 drops of the punctate are added; as effusion sinks to the bottom it gives a cloudy trace (like cigarette smoke), while in case of transudate the reaction is negative.

Microscopy is used to study the precipitate of the pleural fluid obtained by centrifuging. The fluid may clot before or during centrifuging, and the precipitate becomes unsuitable for examination because most of its cells will be captured in clots. To preclude clotting, sodium citrate or heparins added to the test fluid. Precipitate cells are studied by several techniques. Studied are native preparations, dry smears stained after Romanovsky-Giemsa or Papanicolaou. Fluorescence microscopy, histological studies of the precipitate in paraffin, or cell culture is used to detect tumour cells.