Definition

A synovial biopsy is the removal of a piece of tissue lining a joint for examination. The tissue is called the synovial membrane.

Alternative Names

Biopsy - synovial membrane; Rheumatoid arthritis - synovial biopsy; Gout - synovial biopsy; Joint infection - synovial biopsy; Synovitis - synovial biopsy

How the Test is Performed

The test can be done in the operating room or in the physician's office. There are multiple techniques used for synovial biopsy including surgery, arthroscopy or ultrasound guided needle biopsy.

During this procedure:

• Depending on the type of procedure, you may receive general anesthesia, regional anesthesia or local anesthesia. With general anesthesia, you'll be pain free and asleep during the procedure. With regional anesthesia, you'll be awake, but the part of the body with the involved joint will be numb. With local anesthesia, only the joint is numbed and you will be awake during the procedure.

If you are having an arthroscopic procedure:

• The surgeon makes a tiny cut in the skin near the joint.
• An instrument called a trocar is inserted through the cut into the joint.
• A tiny camera with a light is used to look inside the joint.
• A tool called a biopsy grasper is then inserted through the trocar. The grasper is used to cut a small piece of tissue.
• The surgeon removes the grasper along with the tissue. The trocar and any other instruments are removed. The skin cut is closed and a bandage is applied.
• The sample will be sent to the laboratory for evaluation.

If you are having a needle biopsy:

• The physician (radiologist, orthopedist or rheumatologist) will identify the site using ultrasound.
• The site of the biopsy will be cleaned and numbed.
• A needle sized trochar is inserted into the joint.
• A tool called a biopsy needle will be inserted through the trochar. The physician will use the ultrasound to determine where to obtain the tissue from for biopsy. The physician will cut a small piece of tissue with the biopsy needle. Multiple samples may be taken based on the clinical case. The biopsy needle will be removed from the joint and the tissue will be sent to the laboratory for examination.
• The trochar will be removed.
• A small bandage will be applied and stitches are not needed.
• Your physician will determine which method is best given your clinical case.

How to Prepare for the Test

Follow your health care provider's instructions on how to prepare. This may include not eating and drinking anything for several hours before the procedure.

How the Test will Feel

With the local anesthetic, you will feel a prick and a burning sensation. As the trocar is inserted, there will be some discomfort. If the surgery is performed under regional or general anesthesia, you will not feel the procedure.

Why the Test is Performed

Synovial biopsy helps diagnose gout and bacterial infections, or rule out other infections. It can be used to diagnose autoimmune disorders such as rheumatoid arthritis, or uncommon infections like tuberculosis or fungal infections.

Normal Results

The synovial membrane structure is normal.

What Abnormal Results Mean

Synovial biopsy may identify the following conditions:

• Long-term (chronic) synovitis (inflammation of the synovial membrane)
• Coccidioidomycosis (a fungal infection)
• Fungal arthritis
• Gout
• Pseudogout
• Hemochromatosis (abnormal buildup of iron deposits)
• Systemic lupus erythematosus (autoimmune disease that affects the skin, joints, and other organs)
• Sarcoidosis
• Tuberculosis
• Synovial cancer (very rare type of soft tissue cancer)
• Rheumatoid arthritis

Risks

There is a very slight chance of infection and bleeding.

Considerations

Follow instructions for keeping the wound clean and dry until your provider says it is OK to get it wet.

References

El-Gabalawy HS, Tanner S. Synovial fluid analyses, synovial biopsy, and synovial pathology. In: Firestein GS, Budd RC, Gabriel SE, Koretzky GA, McInnes IB, O'Dell JR, eds. Firestein and Kelley's Textbook of Rheumatology. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 56.

Johnsson H, Najm A. Synovial biopsies in clinical practice and research: current developments and perspectives. Clinical Rheumatology. 2021;40(7):2593-2600. PMID: 33274415 pubmed.ncbi.nlm.nih.gov/33274415/.

West SG. Synovial biopsies. In: West SG, Kolfenbach J, eds. Rheumatology Secrets. 4th ed. Philadelphia, PA: Elsevier; 2020:chap 9.