Usefulness of ultrasonography for gout.

Gout is a common arthritis caused by deposition of monosodium urate (MSU) crystals within joints secondary to chronic hyperuricemia. Joint damage can occur during evolution of the disease. The identification of MSU crystals in synovial fluid is the gold standard to diagnose gout. However, the diagnosis is sometimes difficult to do, particularly in atypical clinical presentations or when small joints are involved. Radiography is often normal at the early stage of gout. MRI and CT-scan are costly and availability of these imaging techniques may be problematic in clinical practice. Ultrasonography (US) appears useful for diagnosis and management of the disease. Several ultrasound features evocating gout have been described with different sensitivity and specificity. We reviewed the literature for evidence of the ability and usefulness of US for diagnosis of early-stage and established gout.