Pleural fluid is the fluid found between the membranes lining the thoracic cavity. An excess amount is called a pleural effusion, which can be caused by conditions like heart failure, pneumonia, or rheumatoid arthritis. A sample of pleural fluid is removed through thoracentesis and analyzed to determine if it is a transudate or exudate and diagnose the cause. A transudate is caused by pressure imbalances while an exudate results from inflammation or injury, requiring additional testing to identify conditions like infection, bleeding disorders, or cancer. Test results provide information on the fluid's characteristics, protein levels, and microscopic examination of cells to diagnose the pleural effusion's underlying cause.

1. Pleural Fluid
Examination
Presented By:
Nasir Nazeer

2. Pleural Fluid
Pleural fluid is the fluid that is found between the layers of
the pleura, the membranes that line the thoracic cavity
and surround the lungs.
The space containing the fluid is referred as the pleural
cavity.
Normal pleural fluid consists of a small amount of a thin
(serous) fluid that functions as a lubricant during
breathing.
An excess amount of pleural fluid can be caused by many
conditions and is known as a pleural effusion.
Some common causes of pleural effusions include heart
failure, pneumonia, and autoimmune diseases such
as rheumatoid arthritis.

3. Pleural Fluid
If doctor finds that patient have too much pleural fluid, he may
recommend that a sample of the fluid be removed by a procedure
called thoracentesis and sent for analysis to help determine the
cause (pleural fluid cytology).
With lung cancer, an excess amount of pleural fluid (pleural
effusion) is quite common, and can be either benign (noncancerous) or due to the spread of lung cancer cells into the pleural
cavity (malignant pleural effusion).
Pleural fluid analysis is used to help diagnose the cause of
inflammation of the pleura (pleuritis) and/or accumulation of fluid in
the pleural space (pleural effusion). There are two main reasons for
fluid accumulation, and an initial set of tests (fluid protein, albumin,
or LDH level, cell count, and appearance) is used to differentiate
between the two types of fluid that may be produced.

4. Pleural Fluid (Transudate)
An imbalance between the pressure within blood
vessels (which drives fluid out of the blood
vessel) and the amount of protein in blood
(which keeps fluid in the blood vessel) can result
in accumulation of fluid (called a transudate).
Transudates are most frequently caused
by congestive heart failure or cirrhosis. If the
fluid is determined to be a transudate, then
usually no more tests on the fluid are necessary.

5. Pleural Fluid (Exudate)
Injury or inflammation of the pleurae may cause abnormal collection of
fluid (called an exudate). If the fluid is an exudate, then additional
testing is often ordered. Exudates are associated with a variety of
conditions and diseases, including:



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Infectious diseases – caused by viruses, bacteria, or fungi. Infections may
originate in the pleurae or spread there from other places in the body. For
example, pleuritis and pleural effusion may occur along with or following
pneumonia.
Bleeding – bleeding disorders, pulmonary embolism, or trauma can lead to
blood in the pleural fluid.
Inflammatory conditions – such as lung diseases, chronic lung
inflammation for example due to prolonged exposure to large amounts of
asbestos (asbestosis), sarcoidosis, or auto-immune disorders such
as rheumatoid arthritis and systemic lupus erythematosus
Malignancies
–
such
as lymphoma, leukemias,
lung
cancer, metastatic cancers
Other conditions – idiopathic, cardiac bypass surgery, heart or lung
transplantation, pancreatitis, or intra-abdominal abscesses

6. Additional testing on exudate fluid
Pleural fluid glucose, lactate, amylase, triglyceride, and/or tumor
markers
Microscopic examination – Normal pleural fluid has small numbers of
white blood cells (WBCs) but no red blood cells (RBCs)
or microorganisms. Laboratories may examine the pleural fluid and/or
use a special centrifuge (cytocentrifuge) to concentrate the fluid's cells
on a slide. The slide is treated with a special stain and evaluated for
the different kinds of cells that may be present.
Gram stain – for direct observation of bacteria or fungi under a
microscope. There should be no organisms present in pleural fluid.
Bacterial culture and susceptibility testing – ordered to detect any
microorganisms that may be present in the pleural fluid and to guide
antimicrobial therapy.
Less commonly ordered tests for infectious diseases, such as tests
for viruses, mycobacteria (AFB smear and culture), and parasites.

7. How to prepare patient for the
Test?
The test is no more invasive than having
blood drawn. There is no special
preparation.
Patient should not cough, breathe deeply,
or move during the test to avoid injury to
the lung.
Patient may have a chest x-ray before or
after the test.

8. How to prepare patient for the
Test?
(Contd…)
Patient should be directed to sit on the edge of a chair or
on bed with his head and arms resting on a table.
Clean the skin around the insertion site and drape the
area. A local pain-killing medicine (anesthetic) is injected
into the skin, which stings a bit, but only for a few
seconds.
The thoracentesis needle is inserted above the rib into the
pocket of fluid.
As fluid drains into a collection bottle, many people cough
a bit as the lung re-expands to fill the space where fluid
had been. This sensation normally lasts for a few hours
after the test is completed.
Patient should tell to health care provider if he has sharp
chest pain or shortness of breath

10. Risks involved in Thoracentesis
Collapse of the lung (pneumothorax)
Excessive loss of blood
Fluid re-accumulation
Infection
Pulmonary edema
Respiratory distress
Fainting

11. Test results interpretation
Test results can help to distinguish
between types of pleural fluid and help to
diagnose the cause of fluid accumulation.
The initial set of tests performed on a
sample of pleural fluid helps determine
whether
the
fluid
is
a transudate or exudate.

12. Transudate Fluid and test results
Transudates are most often caused by
either congestive heart failure or cirrhosis.
Typical fluid analysis results include:
Physical characteristics—fluid appears
clear
Protein, albumin, or LDH level—low
Cell count—few cells are present

13. Exudate Fluid and test results
Exudates can be caused by a variety of conditions and
diseases. Initial test results may include:
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Physical characteristics—fluid may appear cloudy
Protein, albumin, or LDH level—high
Cell count—increased
Additional test results and their associated causes may include:
Physical characteristics
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The normal appearance of a sample of pleural fluid is usually light
yellow and clear. Abnormal results may give clues to the
conditions or diseases present and may include:
Milky appearance may point to lymphatic system involvement.
Reddish pleural fluid may indicate the presence of blood.
Cloudy, thick pleural fluid may indicate the presence
of microorganisms and/or white blood cells.

14. Exudate Fluid and test results
(Contd…)
Chemical tests – tests that may be performed in
addition to protein or albumin may include:
Glucose—typically
about
the
same
as blood
glucose levels.
May
be
lower
with
infection
and rheumatoid arthritis.
Lactate levels can increase with infectious pleuritis,
either bacterial or tuberculosis.
Amylase levels may increase with pancreatitis,
esophageal rupture, or malignancy.
Triglyceride levels may be increased with lymphatic
system involvement.
Tumor markers may be increased with some cancers.

15. Exudate Fluid and test results
(Contd…)
Microscopic examination

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Normal pleural fluid has small numbers of white blood cells (WBCs) but
no red blood cells (RBCs) or microorganisms. Results of an evaluation
of the different kinds of cells present may include:
Total cell counts—the WBCs and RBCs in the sample are counted.
Increased WBCs may be seen with infections and other causes of
pleuritis. Increased RBCs may suggest trauma, malignancy, or
pulmonary infarction.
WBC differential—determination of percentages of different types of
WBCs. An increased number of neutrophils may be seen with bacterial
infections. An increased number of lymphocytes may be seen with
cancers and tuberculosis.
Cytology – a cyto-centrifuged sample is treated with a special stain
and examined under a microscope for abnormal cells. This is often
done when a mesothelioma or metastatic cancer is suspected. The
presence of certain abnormal cells, such as tumor cells or immature
blood cells, can indicate what type of cancer is involved.

16. Exudate Fluid and test results
(Contd…)
Infectious disease tests
Following tests may be performed to look for microorganisms if
infection is suspected:
Gram stain – for direct observation of bacteria or fungi under a
microscope. There should be no organisms present in pleural fluid.
Bacterial culture and susceptibility testing – If bacteria are present,
susceptibility testing can be performed to guide antimicrobial therapy.
If there are no microorganisms present, it does not rule out an
infection; they may be present in small numbers or their growth may
be inhibited because of prior antibiotic therapy.
Less commonly, if testing for other infectious diseases is performed
and is positive, then the cause of the pericardial fluid accumulation
may be due to a viral infection, mycobacteria (such as the
mycobacterium that causes tuberculosis), or aparasite.