Gout is an inflammatory arthritis, which usually has a sudden onset of symptoms. It can affect any joint, but the small joint at the base of the big toe is the most commonly affected join that gets involved in an acute attack of gout.
Medical history and physical examination
The doctor will ask you questions regarding location of the pain, time and pattern of the pain, stiffness of the joint and any other associated symptoms. In most cases, gout attacks one joint at a time whereas other types of arthritis such as systemic lupus and rheumatoid arthritis affect multiple joints simultaneously. During examination, the doctor will check the involved joint for pain, tenderness, redness, movement and any deformity. The doctor will examine other joints as well.
Joint fluid analysis: Your doctor may take fluid from the affected joint if gout is suspected. The procedure of aspirating joint fluid with a needle and syringe for test is known as arthrocentesis. Arthrocentesis is the most reliable test to diagnose the presence of uric acid crystals in joint fluid. The procedure is done under local anaesthesia (so that you do not feel any pain during the procedure). A sterile needle and syringe is used to aspirate (take out) fluid in an aseptic manner from the inflamed joint. The aspirated fluid is examined for uric acid crystals and infection. Uric acid crystals are best seen with a special polarising microscope. Gout can be diagnosed based on the presence of urate crystals from material aspirated from tophi nodules and bursitis fluid.
If the history and symptoms are characteristic of gout, your doctor may diagnose gout clinically and start treatment without doing arthrocentesis. Confirming the diagnosis by doing arthrocentesis, however, is preferable since many other conditions (such as psoriatic arthritis, rheumatoid arthritis and even infection in the joint) can mimic gout.
Imaging Studies: Your doctor may recommend x-rays (radiographs) or other imaging studies such as MRIs (Magnetic Resonance Imaging scans) or CT scans if the diagnosis is not clear. X-rays can show tophi-crystal deposits and bone damage as a result of repeated bouts of inflammation. X-rays can also be useful to monitor the effects of chronic gout on joints.