A 68-year-old man is evaluated on postoperative day 3 following an uncomplicated open chol… — USMLE Step 2 CK

A $68$ -year-old man is evaluated on postoperative day $3$ following an uncomplicated open cholecystectomy. He reports the sudden onset of excruciating pain and swelling in his right knee that woke him from sleep early this morning. His temperature is $38.2^\circ\text{C}$ ( $100.8^\circ\text{F}$ ), blood pressure is $135/85 \text{ mm Hg}$ , and pulse is $98/\text{min}$ . Medical history is significant for type 2 diabetes mellitus, hypertension, and stage 3 chronic kidney disease. Laboratory studies show a serum creatinine level of $2.2 \text{ mg/dL}$ (baseline $2.1 \text{ mg/dL}$ ) and a blood urea nitrogen level of $34 \text{ mg/dL}$ . Physical examination reveals a warm, erythematous, exquisitely tender right knee with a visible effusion and severely limited range of motion. Arthrocentesis is performed, yielding $5 \text{ mL}$ of turbid yellow fluid. Synovial fluid analysis shows a leukocyte count of $45,000/\mu\text{L}$ with $85\%$ neutrophils. Polarized light microscopy reveals needle-shaped, negatively birefringent crystals. Gram stain shows no organisms. Which of the following is the most appropriate next step in management?

Intra-articular glucocorticoid injectionAnswer
B
Intravenous vancomycin and ceftriaxone
C
Oral indomethacin
D
Lower extremity venous duplex ultrasonography
E
Intravenous furosemide

Answer

Intra-articular glucocorticoid injection

The correct answer is intra-articular glucocorticoid injection. This patient is experiencing an acute gout flare, confirmed by the pathognomonic finding of needle-shaped, negatively birefringent monosodium urate crystals in the synovial fluid. While oral nonsteroidal anti-inflammatory drugs (NSAIDs) and colchicine are standard first-line therapies for acute gout, this patient has significant baseline renal impairment (creatinine

2.2 \text{ mg/dL}

). NSAIDs are strictly contraindicated in chronic kidney disease due to the risk of precipitating acute renal failure. Colchicine must also be avoided or heavily dose-adjusted in severe renal impairment. For patients presenting with monoarticular acute gout who have contraindications to systemic medications, an intra-articular glucocorticoid injection provides rapid, targeted relief with a negligible risk of systemic side effects.

Step-by-Step Solution

Analyze the synovial fluid results and microscopy findings.

The presence of needle-shaped, negatively birefringent crystals confirms the diagnosis of an acute gout flare.

Establishing a definitive diagnosis is required before selecting targeted pharmacotherapy.

Evaluate the patient's comorbidities and laboratory values.

The patient has stage 3 chronic kidney disease with a serum creatinine of

2.2 \text{ mg/dL}

Renal impairment dictates which acute gout therapies are safe to administer.

Select the optimal treatment modality based on the clinical constraints.

Intra-articular glucocorticoid injection is chosen.

NSAIDs are contraindicated due to the kidney disease, and intra-articular injection is highly effective and safe for monoarticular disease.

Key Concept

Management of acute gout flares in patients with contraindications to systemic therapies (e.g., chronic kidney disease).

Estimated Time:1m 30s

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