Joint Fluid Analysis
How It Is Done continued...
A long, thin
needle is slowly inserted in the joint area. A syringe attached to the needle
is used to remove a sample of joint fluid. Samples of the fluid may be put in
special tubes or containers and sent to the lab. A cortisone shot may be given
into the joint before the needle is removed, to help keep fluid from building up again.
A tight (pressure)
bandage will be placed over the site to reduce swelling and bruising. An
elastic bandage may also be wrapped around your joint, such as your knee, to
How It Feels
You will feel a prick or sting when the
anesthetic is given. You may feel tingling, pressure, pain, or fullness in your
joint as the fluid is removed.
There is very little chance of having a problem
after a joint fluid analysis. Infection, bleeding, or damage to the
tendon, nerve, or joint is rare.
Sometimes your doctor may not be able to draw any fluid out. The joint
space may be too small, you may have scar tissue in the joint space, or there
may not be any fluid in the joint.
The joint may be sore for 1 to
2 days after the procedure. If you have a cortisone shot, you may have some
soreness or irritation at the site of the shot for 1 to 2 days. Avoid strenuous
use of the joint for 2 to 3 days.
Joint fluid analysis is a test to look
at joint fluid under a microscope for problems such as infection,
inflammation, or bleeding. The test can help find the
joint pain or swelling.
The results of a
joint fluid analysis are usually available the same day. The results from a
culture are usually available in a few days.
Joint fluid analysis
| Color and clarity
Clear to light yellow
Red (bloody) or milky white
| Blood cell count
No large numbers of red or white blood
Large numbers of red or white blood
| Crystals (seen under a special microscope with
| Gram stain and culture
No bacteria are seen and no organisms grow
in the culture.
Bacteria are seen or organisms grow in the
Color and clarity. Slightly cloudy fluid may be
caused by inflammation, gout, or pseudogout. A deep, dark red color may be
caused by bleeding in the joint. Milky white may be caused by infection or
Blood cell count. Large numbers of red blood
cells may be caused by bleeding in the joint from injury, inflammation, or
abnormal clotting of the blood. Large numbers of white blood cells may be
caused by gout, pseudogout, other types of
arthritis (such as
psoriatic arthritis, injury, or infection.
Presence of crystals. Uric acid crystals in the
joint mean you have gout. Calcium pyrophosphate crystals mean you have
Gram stain and culture. Bacteria seen under a
microscope on the Gram stain (a special dye) of the joint fluid may be caused
by an infection. Bacteria that grows out of a culture plate in 1 to 2 days
confirms the presence of an infection.