When should someone with gout have the fluid taken out of the joint and sent to the lab? I’ve never had this done but someone else I know has. Just wondering why there’s a difference in how we are treated when we both have the same problem.

Anyone who has ever suffered an attack of gout knows just how painful it can be. The red, tender, and swollen joint can be so painful that even the touch of a sock or sheet can be excruciating.

Painful joint symptoms associated with gout are caused by the deposit of uric acid crystals in the joint and in the surrounding soft tissues. The most typical pattern is an attack that affects the big toe but other joints such as the elbow, wrist, fingers, and even the shoulder can be involved.

Before starting treatment, the physician will make sure the problem isn’t a case of joint infection from cellulitis or septic arthritis. If there is any doubt about the diagnosis, a small amount of fluid can be drawn out of the joint. Using a syringe to collect synovial fluid from a joint is called an arthrocentesis.

The fluid will be analyzed in the lab in order to make the final diagnosis. If it’s really gout, there will be urate crystals seen under the microscope. Sometimes those crystals are visible around the painful joint so the lab test isn’t needed.

The decision to perform an arthrocentesis is based on the patient’s history, physical exam, other lab results, and possibly X-rays taken during the initial evaluation. But studies show that arthrocentesis isn’t needed if the patient has four out of eight clinical findings.

These are the things the physician looks for: only one joint affected (usually the big toe), no more than four joints involved, more than one episode of painful joint symptoms typical of gout, visible crystals called tophi around the affected joint, and hyperuricemia (high levels of uric acid in the blood).

Most of the time, if the problem is really gout, the clinical picture is clear. But the “gold standard” for a clear and definitive diagnosis remains the just of arthrocentesis (joint fluid analysis).