Analysis of pleural fluid        

EXAMINATION OF SPUTUM.

Sputum is a pathological material that is expelled from the respiratory organs during the coughing act. The study of the sputum gives information concerning the pathology of the respiratory organs and in some cases helps to establish its etiology.

Specimens of sputum for examination are collected by having the patient cough up the material from the bronchi or lungs and expectorate it into a container. The container most commonly used is a waterproof, waxed sputum cup, though in disorders such as bronchiectasis, a tall glass container (when this type of container is used, the nurse covers the outside of the container with a paper towel, fastened in place with Scotch tape, so that the contents are not visible to the patient and his visitors). A paper cover affixed to the top of the container may be used to observe the characteristic layering of the sputum.

If a sterile specimen is desired, the used container is generally a wide-mouthed glass bottle with a paper or screw cap, or a sterile Petri dish. Care should be taken in either instance to prevent the contamination of the inside of the container.

Specimens are usually collected in the morning before food is taken. The mouth should be cleaned previous to the collection of the sputum because the presence of food particles in the material may be confused in the examination. The patient must be instructed to raise material from the lungs by coughing and not simply expectorate saliva or the discharges of the nose and throat. When the person is unable to produce a specimen, sputum may be obtained through nasotracheal suctioning.

Occasionally the physician wishes to have the total sputum expectorated in the 24-hour period examined. The size of the using container will depend upon the quantity of sputum, but in most instances the waved sputum cup is used. The waxed cup is desirable because it can be so easily destroyed after use. The most common collected specimen is the small quantity that is examined microscopically.

Examination of the sputum can be divided into the several stages: macroscopic, microscopic, bacterioscopic. Special examinations can be provided for determining of tuberculosis mycobacteria or atypic cells.

 Macroscopic Examination of Sputum.The study begins with observation of the sputum first in transparent bottle and then in a Petri dish. General properties, color and consistency of the sputum are noted.

Sputum amount:normally no sputum is expectorated, and in disease in which there is sputum produced, the amount may vary from a minute quantity to several hundred cubic centimeters. Large amount of sputum is expectorated in lung abscesses and bronchiectasis.

Coloris observed and it is varied considerably also. Sputum may be colorless, grey, or yellow. It depends on intensity of the inflammatory process.

In lobar pneumonia the sputum has a rusty color (blood is not expectorated from the respiratory tract immediately but it stays there for some time, the hemoglobin converts into hemosiderin to give a rusty hue to the sputum), while in lung abscesses, bronchiectasis and carcinoma the sputum may be greenish.

Blood may be detected in sputum by a red color:

if it's bright red, it is of recent origin (it occurs in pulmonary hemorrhage - tuberculosis, cancer, bronchiectasis);

if it's dark, it has probably been in the lung for some time (lung infarction or congestion in the lesser circulation);

if it's pink and serous-stained foamy, it is lung edema;

if mucous-bloody or bloody-purulent, it is gangrene or lung abscesses.

The consistency of sputum varies from a thin watery fluid to thick purulent material.

Mucoid sputum is usually colorless, it occurs inacute bronchitis.

Serous sputum is also colorless, liquid, and foamy, it occurs in pulmonary edema.

Mucopurulent sputum is yellow or greenish and tenacious; it is characteristic of chronic bronchitis, tuberculosis.

Purulent uniform semi liquid sputum in large amount with a greenish-yellow tint is typical for the ruptured lung abscesses.

Settled sputum may form layers. Three - layer sputum is characteristic of chronic purulent processes (brochiectasis, abscesses). The upper layer is mucopurulent, the middle one is serous, and the lower layer is pus. Sometimes purulent sputum is separated into 2 layers: serous and purulent.

Odor.Sputum is usually odorless. Foul odor of freshly expectorated sputum depends on the putrefactive decomposition of tissues (gangrene, degrading cancer tumor) or on the decomposed protein of the sputum retained in various cavities (abscesses, bronchiectasis).

Admixture.The following elements can be seen in the sputum by an unaided eye:

- lentil is compact lenticular greenish-yellow formations consisting of calcified elastic fibers, cholesterol crystals and soaps containing tuberculosis mycobacteria, they occur in tuberculosis;

- Dittrich's plugs, that resemble the lenticular formations in appearance and composition but free of tuberculosis mycobacteria and having offensive odor on pressing, occurin gangrene, chronic abscesses and fetid bronchitis.

Themedium of sputum is alkaline as a rule; it becomes acid in the presence of gastric juice and during decomposition; it helps differentiate between hemoptysis and hematemesis.                                                                                                                                                                                

 Microscopic study of the sputum can be done with native and stained preparations. Next specific elements can be revealed:

Squamosus epithelium gets into the sputum mostly from the mouth and is diagnostically unimportant.

Columnar ciliated epithelium is contained in small quantity in any sputum, but its large amounts are found in bronchitis, bronchial asthma and other affections of the respiratory ducts.

Curshmann' spirals are mucous threads containing eosinophilis leucocytes.

Charcot-Leyden' crystals; they consist of protein released during decomposition of eosinophils.

Curshmann' spirals and Charcot-Leyden' crystals are found in the sputum mostly in bronchial asthma.

Single eosinophils can occur in any sputum; large amount of eosinophils are found in bronchial asthma, eosinophilic infiltrations, helminthic invasions of the lungs.

Erythrocytes appear during decomposition of lung tissue, in acute lobar pneumonia, congestion in the lesser circulation, lung infarction, etc.

Leucocytes can be found in any sputum (to 4 - 6 in the microscope's vision field), while their large amount are typical for inflammatory and especially purulent processes.

Alveolar macrophages are large cells of reticulohistiocyte etiology. Their cytoplasm contains many inclusions. Small quantities of alveolar macrophages are contained in any sputum, but their large amount is found in inflammatory diseases (pneumonia).

Heart-disease cells or siderophages (alveolar macrophages with brown-yellow color from hemosiderin inclusions) occur when erythrocytes get into the alveolar cavities due to congestion in the lesser circulation. It can occur in mitral stenosis, lung infarction and also in acute lobar pneumonia.

Crystals of hematoidin can be found in the sputum after pulmonary hemorrhage (provided blood is not liberated with the sputum immediately).

Elastic fibers are found in the sputum during decomposition of the lung tissue in tuberculosis, cancer and abscesses.

Malignant tumor cells are often present in the sputum, especially if the tumor degrades or grews endobronchially.

Bacteriological examination of sputum helps to identify the microbe and to determine its virulence and drug-resistance. It is necessary to prescribe correct medicamentous therapy.

Several microbes can be differentiated by bacterioscopy. These are Gram-positive capsulated pneumococcus, streptococcus, staphylococcus, klebsiella, etc. All these microorganisms occur in small quantities in the sputum of the healthy persons respiratory ducts and only become pathogenic under certain unfavorable conditions when they cause pneumonia, lung abscesses, bronchitis, etc.

If acid-fast bacilli with the morphologic characteristics of tubercle bacilli are found in the sputum, the diagnosis of tuberculosis is generally made.

Actinomycetes and candida albicans are fungus occurring in the sputum, they affect the lungs during prolonged antibiotic therapy of asthenic patients.

The Example of Analyses:

STUDY OF THE SPUTUM

     Macroscopic:                              Microscopic:

Amount - 20 ml

Curshmann’ spirals - absent

Color - yellow

Charcot-Leyden’ crystals - absent

Character - mucoid

Eosinophils - 3-5 in vision field

Consistence - semifluid

Elastic fibres - absent

Admixture - absent

Leucocytes - 10-20 in vision field

Erythrocytes - absent

Squamosus epithelium - 20-25 in vision field

     Bacterioscopical analysis

Tuberculosis mycobacteria - absents

Another microorganisms - pneumococcus

Conclusion: presence of yellowishcolor, mucoidcharacter, semi fluid consistence; increased amount of leucocytes and squamosus epithelium; presence of pneumococcus indicate inflammatory process. Such sputum can be in bronchitis.

PLEURAL FLUID EXAMINATION.

The amount of fluid contained in the pleural cavity of a healthy person is insignificant. Its composition is close to that of lymph. The fluid serves as a lubricant to decrease friction between the pleural membranes during respiration.

The volume of pleural fluid may increase (hydrothorax) in disordered circulation of the blood and lymph in the lungs. It can be either transudate (of non inflammatory origin) oreffusion (occurring in inflammatory affections in the pleura). Effusion can be also due to clinical causes such as primary infection of the pleura or it can be a symptom attending some general infections and some diseases of the lungs or mediastinum (rheumatism, infarction, cancer and tuberculosis of the lung, etc).

A thoracocentesis is performed to obtain pleural fluid for analysis, to remove pleural fluid, or to instill medication. Specimens are examined for gross appearance, consistency, glucose, protein content, cellular composition. Specimens are also examined cytologically for malignant cells and cultured for pathogens.

During thoracocentesis the physician inserts a large-bore needle through the chest wall into the pleural space. The procedure is performed using strict sterile technique. The nurse positions the patient upright with arms and shoulders supported on an over bed table. If unable to sit, the patient is placed on the unaffected side.

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

Macroscopic Examination.

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, hemorrhagic, chylous, chylous-like.

Transudate and serous effusion are clear and slightly opalescent.

Turbidity of the fluid can be due to abundance of leucocytes (seropurulent and purulent effusion), erythrocytes (hemorrhage effusion), fat drops (chylous effusion) or cell detritus (chylous-like effusion). The chylous fluid can be due to congestion of lymph or destruction of the thoracic duct by a tumor or aninjury. The chylous-like character is given to the pleural fluid by fatty degeneration of cells contained in ample quantity.

The color of transudate may be light yellow; serous effusion from pale yellow to golden.

Purulent effusion is greenish or greenish-yellow.

Depending on the amount of the hemorrhage and also on the time of blood retention in the pleura, the hemorrhagic fluid can be pink to dark red or even brown.

Chylous effusion looks like thin milk.

The consistency of pleural transudate and effusion is usually liquid. Purulent fluid can be thick, cream-like.

Odor. 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 transudate is about 1,015 g/cm³ and of the effusion is higher 1,015.

Protein content is lower in transudate than in the effusion, and not higher than 3%, the pleural effusion contains more than 3% of protein.

Rivalta's reaction is positive in effusion and it is negative in transudate.

Microscopy is used to study the precipitate of the pleural fluid obtained by centrifuging. The quantity of formed elements is then assessed (many, moderate, few number). An accurate calculation of leucocytes and erythrocytes is unimportant because their quantity in the preparation depends largely on the duration and speed of centrifugation.

A small quantity of erythrocytes can be contained in any punctate because of puncturing of the tissue. Their number is high in hemorrhagic effusion in patients with tumors, injuries and hemorrhagic diaphedesis.

Leucocytes are scarce in transudates, which contain many mesothelium cells.

The leukocytecount increases in bacterial infections of the pleura. It is moderate in the serous effusion and it is many in purulent effusion.

Microbiological Examination.Transudates used for microbiological studies are sterile as a rule, but they can be infected during repeated thoracocentesis. Effusion may be sterile in rheumatic pneumonia or lung cancer.

The bacteria can often be detected in pleurisy caused by pyogenic flora.

In order to prescribe a correct therapy, the revealed microbes are tested for antibiotic sensitivity.

The Examples of Analyses:

ANALYSIS OF PLEURAL FLUID

Macroscopic:                                             Microscopic:

Amount  - 500 ml

Erytrocytes - few

Color - gold

Leucocytes - moderate

Relative density  - 1,020

Cells mesothelium - few

Protein  - 3,5%

Cancer Cells - absent

Rivalta's reaction -  positive

       Conclusion:relative density higher than 1,015, protein - higher than 3%, positive Rivalta's reaction indicate effusion; moderate leucocytes count is typical for serous effusion.

   Macroscopic:                                           Microscopic:

Amount - 500 ml

Erytrocytes - few

Color - gold

Leucocytes - few

Relative density - 1,010

Cells mesothelium - few

Protein - 2,5%

Cancer Cells - absent

Rivalta's reaction - negative

       Conclusion:relative density smaller than 1,015, protein - smaller than 3%, negative Rivalta's reaction indicate transudate.

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