Images in Primary Care Medicine: Point-of-Care Ultrasound in Gout

Abstract

Gout is the most common crystal arthropathy and is frequently diagnosed and managed by primary care physicians. Point-of-care ultrasound (POCUS) is a valuable tool to aid in the diagnosis of gout via the identification of the double contour sign, aggregates of crystals, tophi, and erosions. In addition, POCUS can aid in the management of gout by recognizing early signs of gout, monitoring the effectiveness of urate-lowering therapy, and guiding aspiration and corticosteroid injection.

Keywords: crystal arthropathy; gout crystals; point-of-care-ultrasound; primary care medicine; ultrasound-guided.

Figure 1. American College of Rheumatology and European League Against Rheumatism criteria for diagnosis of gout

Step 1: Entry criterion necessary for the diagnosis - at least one episode of swelling, pain, or tenderness in a peripheral joint/bursa; if NO, the diagnosis of gout has been ruled out Step 2: Sufficient criteria (if YES, the diagnosis of gout is positive) - the presence of MSU crystals in a symptomatic joint, bursa, or tophus; if present, no need to proceed to Step 3 Step 3: Classification criteria - to be used if Step 2 sufficient criteria not met (at least 8 points required for the diagnosis of gout)

Figure 2. Double contour sign

The arrows highlight the double contour sign.

Figure 3. Tophi

Images a-d demonstrate tophi in the synovium of multiple joints.

Figure 4. Aggregates

On the left, a-d are views of the joint of interest without labels. The images on the right are the same images with arrows highlighting several highly reflective aggregates within the joint space and soft tissue.