Soru

A $68$-year-old man is evaluated in the surgical ward for a fever on postoperative day $5$ following an uncomplicated right total knee arthroplasty. His temperature is $38.4^\circ\text{C}$ ($101.1^\circ\text{F}$), pulse is $98/\text{min}$, respirations are $16/\text{min}$, and blood pressure is $135/85\text{ mmHg}$. The patient reports a new, deep aching pain in his right calf that is distinct from his surgical site pain. He has a medical history of hypertension and type $2$ diabetes mellitus. Current medications include prophylactic subcutaneous enoxaparin, lisinopril, and metformin. Physical examination reveals a clean and dry surgical incision with mild, expected postoperative swelling around the knee, but no erythema, fluctuance, or purulent drainage. There is moderate, asymmetric swelling and tenderness in the right posterior calf. Passive dorsiflexion of the right foot elicits pain in the calf. Lungs are clear to auscultation bilaterally. A Foley catheter was removed on postoperative day $1$, and he has been voiding without dysuria. Which of the following is the most appropriate next step in management?