What Is Synovial Fluid?
Synovial fluid is the thick liquid that lubricates your joints and keeps them moving smoothly. It’s on all of your joints, including in your knees, shoulders, hips, hands, and feet.
Joint conditions like arthritis, gout, infections, and bleeding disorders can change how your synovial fluid looks and feels. A sample of this fluid taken during a procedure called an arthrocentesis can help your doctor figure out what’s causing your symptoms.
What Is a Synovial Fluid Analysis?
A synovial joint fluid analysis is a group of tests your doctor can use to diagnose problems with your joints.
Joint conditions like arthritis, gout, infections, and bleeding disorders can change how your synovial fluid looks and feels. A sample of this fluid taken during a procedure called an arthrocentesis can help your doctor figure out what’s causing your symptoms.
What’s The Purpose of a Synovial Fluid Analysis?
If you have joint symptoms like:
- Pain
- Redness
- Swelling
- Fluid buildup
Synovial fluid analysis can also help your doctor figure out if you have:
- A condition that inflames your joints, like gout, rheumatoid arthritis, and lupus
- An infection like septic arthritis
- Bleeding disorders like hemophilia or von Willebrand disease
- A disease that break down joints over time, like osteoarthritis
Your doctor might also use this test to see if your treatment for your joint condition is working.
If your doctor thinks you need this test, ask them how to prepare. Let them know if you take blood thinners or any other medication.
How Is a Synovial Fluid Analysis Performed?
First, your doctor will give you a local anesthetic to numb your joint. Then, they'll put a needle in and take some fluid out. How much depends on the size of the joint and how many tests you're going to have.
Your doctor will send your fluid to a lab, where a technician will do one or more of these:
- Check your fluid's color and thickness
- Measure chemicals like glucose, protein, and uric acid
- See how many red and white blood cells and crystals your fluid has
- Test for bacteria, viruses, or other germs
What Your Results Mean
If the results are abnormal:
- The synovial fluid may be cloudy or thick.
- A high white blood cell count could mean you have an infection or another medical condition.
- A high uric acid level and crystals could signal gout.
- A high red blood cell count could result from:
- Injury
- Blood in the joint
- Bleeding disorder
Normal synovial fluid is:
- Clear
- Colorless or pale yellow
- Stringy
- Free of bacteria, viruses, and fungi
Ask your doctor what your results mean and how they might affect your treatment.