Gout is an inflammatory disorder characterized by hyperuricemia and the deposition of monosodium urate crystals, resulting in episodic gout flares, gouty arthropathy, and tophi formation. Accurate diagnosis is critical for appropriate treatment of gout, but the differential diagnosis between gout and other causes of arthritis can be challenging. The gold standard for the diagnosis of gout is the microscopic analysis of synovial fluid aspirate, which reveals negatively birefringent needle-shaped monosodium urate crystals in polarized light microscopy. However, joint aspiration can be technically challenging in patients with small amounts of joint fluid, and identification via joint aspiration is not always possible. In addition, synovial fluid aspiration may not reveal uric acid crystals in up to 25% of patients with gout
Ultrasound may come to replace conventional invasive examinations in clinical practice. A meta-analysis done by Lee et al (2017) demonstrates that ultrasound offers good diagnostic accuracy. It plays an important role in the diagnosis of gout and can assist in differentiating gout from other arthritic diseases. Ultrasound is therefore an important component of the noninvasive assessment of gout.