this procedure, a needle is used to withdraw (aspirate) synovial
fluid, which is the viscous liquid that helps to lubricate and
nourish bones and cartilage within the joints. The fluid sample
is then sent to a laboratory for analysis. The most common site
for joint aspiration is the knee, but it can be performed on
any major joint, including the shoulder, elbow, hip, ankle, and
wrist. Joint aspiration may also be done therapeutically to relieve
pain and swelling caused by accumulation of fluid in a joint.
Purpose of the Test
To aid in the
diagnosis of certain joint disorders such as infection, rheumatoid
arthritis, and gout.
To determine the cause of joint inflammation
or effusion (excessive accumulation of fluid inside the joint).
the effectiveness of antibiotic medication used for the treatment
of infectious arthritis.
to relieve the discomfort caused by joint effusion or to administer
medications, such as corticosteroids, into the joint.
Who Performs It
should not be performed in areas with a skin or wound infection.
may be done in a hospital or in an outpatient setting.
blood sample is taken from a vein in the arm (a procedure called
venipuncture) to compare chemical test results with analyses
of the synovial fluid obtained during joint aspiration.
Before the Test
may ask you to avoid food and fluids for 6 to 12 hours if glucose
levels in the synovial fluid are to be measured. If not, fasting
You will be
instructed to remove whatever clothing is covering the joint
to be aspirated.
What You Experience
The skin at
the site of needle insertion is cleansed with an antiseptic solution,
and a local anesthetic is injected to numb the area.
The area around
the joint may be wrapped in elastic bandages to compress the
maximum amount of fluid into the joint space.
A needle is
quickly inserted through the skin and into the joint space. You
will feel pressure or slight pain as it is inserted.
Fluid is withdrawn
through the needle and placed into multiple specimen containers.
If a corticosteroid
or another medication (such as an antibiotic) is administered,
the syringe is detached, leaving the needle in the joint. Another
syringe is then attached, and the medicine is injected.
takes 3 to 5 minutes.
Risks and Complications
rare complications include infection or bleeding in the joint
After the Test
is withdrawn and pressure is applied to the puncture site with
sterile gauze pads for 3 to 5 minutes.
bandage is then applied to avoid re-collection of fluid or accumulation
of blood underneath the skin (hematoma).
Apply ice or
cold packs to the joint for 24 to 48 hours to reduce any swelling
and pain. You may also be given pain-relieving medication.
You may resume
your normal activities, but try to avoid excessive use of the
affected joint for several days.
doctor immediately if you develop increased pain or fever.
containers may be sent to several different laboratories for
examination, and the fluid is analyzed for the presence of abnormal
components. For example, bacteria may be present in cases of
infectious arthritis, elevated white blood cells suggest an inflammatory
disorder such as rheumatoid arthritis, and uric acid crystals
indicate a diagnosis of gout.
If a definitive
diagnosis can be made, the doctor will recommend an appropriate
course of treatment.
In some cases,
additional tests may be required to establish a diagnosis or
determine the extent of a problem.
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