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Thoracentesis is a procedure to remove fluid
from the space between the lungs and the chest wall called the pleural space.
It is done with a
needle (and sometimes a plastic catheter) inserted
through the chest wall. Ultrasound pictures are often used to guide the placement of the needle. This pleural fluid may be sent to a lab to determine
what may be causing the fluid to build up in the pleural space.
Normally only a small amount of pleural fluid is present in the pleural
space. A buildup of excess pleural fluid (pleural effusion) may be caused by many
conditions, such as infection, inflammation,
heart failure, or cancer. If a large amount of fluid
is present, it may be hard to breathe. Fluid inside the pleural space may
be found during a physical examination and is usually confirmed by a chest
Thoracentesis may be done to:
You will be asked to sign a consent
form that says you understand the risks of the test and agree to have it done.
Talk to your doctor about any concerns you have
regarding the need for the test, its risks, how it will be done, or what the
results will mean. To help you understand the importance of this procedure,
fill out the
medical test information form(What is a PDF document?).
Tell your doctor if you:
Also, certain conditions may increase the difficulty of
thoracentesis. Let your doctor know if you have:
A chest X-ray is usually done before the procedure. Your
doctor may order certain blood tests, such as a
complete blood count (CBC) and clotting factors,
before your procedure.
This procedure may be done in your
doctor's office, in the X-ray department of a hospital, in an emergency room,
or at your bedside in the hospital. Your doctor may have a nurse assist with
You will need to take off all or most of your
clothes (you may be allowed to keep on your underwear if it does not interfere
with the procedure). You will be given a cloth or paper covering to use during
the procedure. During the procedure, you will be seated but leaning forward on
a padded bedside table. If your test is done in the X-ray department, X-rays or
ultrasound may be used to confirm the location of
fluid in your chest.
The needle site between your ribs will be
cleaned with an antiseptic solution. Your doctor will give you a
local anesthetic in your chest wall so you won't feel
any pain when the longer needle that withdraws the fluid is inserted. Once the
area is numb, your doctor will insert the needle to where the fluid has
collected (pleural space). You may feel some mild pain or pressure as the
needle enters the pleural space.
A syringe or a small tube
attached to a vacuum bottle is used to remove the pleural fluid. Your doctor
will collect fluid to send to the lab. Once the fluid
is removed, the needle or small tube is removed and a bandage is put on the
procedure takes about 10 to 15 minutes.
An X-ray may be taken right after the procedure to make
sure that no complications have occurred.
If more pleural fluid collects and
needs to be removed, another thoracentesis may be done later.
When you are given the shot to numb your
skin at the needle site, you will feel a sharp stinging or burning sensation
that lasts a few seconds. When the needle is inserted into the chest wall, you
may again feel a sharp pain for a few seconds.
When the pleural
fluid is removed, you may feel a sense of "pulling" or pressure in your chest.
Tell your doctor or nurse if you feel faint or if you have any shortness of
breath, chest pain, or uncontrollable cough.
If a large amount of
pleural fluid was removed during the procedure, you will probably be able to
breathe more easily.
Thoracentesis is generally a safe procedure. A
chest X-ray may be done right after the procedure to make sure that no
complications have occurred. Complications may include:
Thoracentesis is a procedure to remove
fluid from the space between the lungs and the chest wall called the pleural
space. Results from a lab are usually available in 1 to 2 working days. If the
fluid is being tested for an infection, such as
tuberculosis, results may not be available for several
A small amount of clear,
colorless, or pale yellow pleural fluid, usually less than
20 mL (0.7 fl oz), is normally
present. No infection, inflammation, or cancer is found.
A large amount of pleural
fluid is present.
Fluid may be labeled as either
a transudate or an exudate. The difference between these two types of fluid has
to do with the amount of protein and other substances found in the
Reasons you may not be able to
have the test or why the results may not be helpful include:
Other Works Consulted
Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Current as of:
November 1, 2012
Adam Husney, MD - Family Medicine & Robert L. Cowie, MB, FCP(SA), MD, MSc, MFOM - Pulmonology
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