Synovial Fluid Analysis

Synovial fluid analysis can help diagnose the cause of swelling, pain or redness in joints. In some cases, it helps in removing the fluid to provide relief from joint pain. Doctors recommend this test when they suspect the following:

• An infection in the joint
• Bleeding in the joint post-injury
• Various types of arthritis like gout

Generally, a synovial fluid analysis does not require any preparation. However, you should ask your doctor if fasting is required before the test.

Also, it is important to inform the doctor if you are taking any blood-thinning medications, such as clopidogrel, aspirin or warfarin, as these can affect the results of this test.

(Consult physician online)

A synovial fluid sample is collected using the following steps:

• The joint area is cleaned with an antiseptic solution
• A sterile needle is inserted through the skin into the joint space
• The fluid is drawn out into a sterile syringe through the needle
• The fluid is sent to a laboratory for testing
• The procedure typically lasts for about 1 to 2 minutes.
• Sample’s colour and clarity are checked at the laboratory
• The sample is further placed under a microscope to count the white and red blood cells
• Presence of bacteria or crystals (in the case of gout) is also examined
• Lactate dehydrogenase, glucose, uric acid and proteins are measured
• The concentration of cells in the fluid is measured
• A culture test is performed on the fluid sample to look for bacterial growth

At times, numbing medicines are first injected into the skin with a small needle, which causes a stinging effect. Next, a larger needle is used to draw out the fluid sample.

A rare risk associated with this test is an infection in the joint due to repeated aspirations and bleeding in the joint space. The test might cause some discomfort if the tip of the needle touches the bone.

Normal results:
A normal sample of synovial fluid should look clear, straw-coloured and moderately viscous.

Abnormal results:
Following are the abnormal changes in the appearance of synovial fluid and the diseases that they might indicate:

• Cloudy synovial fluid: Indicates the presence of crystals, microbes and white blood cells
• Reddish synovial fluid: Indicates the presence of blood, which might occur due to a body-wide bleeding problem or a joint injury
• Less viscous synovial fluid: Suggests the possibility of inflammation
• Excess synovial fluid: Indicates cartilage injury or osteoarthritis (a type of arthritis that occurs when flexible tissue at the bone ends wear down)

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.