Review Question - QID 214987

A 55-year-old man presents to the emergency department for crushing, substernal chest pain and undergoes a coronary artery bypass graft (CABG) procedure. His immediate postoperative course was uncomplicated and he is now recovering on the surgical floor. On postoperative day 5, he begins to complain of swelling and crampy pain in his right leg. His past medical history includes hypertension, hyperlipidemia, coronary artery disease, peripheral arterial disease, and diabetes. His current medications are aspirin, metoprolol, atorvastatin, and insulin. The patient’s temperature is 98.8°F (37.1°C), blood pressure is 142/82 mmHg, pulse is 72/min, and respirations are 16/min. Physical exam reveals swelling and warmth involving the right thigh and leg. All surgical incision and venipuncture sites are clean and dry. His laboratory results are as follows:

Preoperative:
Hemoglobin: 13.2 g/dL
Hematocrit: 39.6 %
Leukocyte count: 7,500/mm^3
Platelet count: 160,000/mm^3

Postoperative day 5:
Hemoglobin: 9.8 g/dL
Hematocrit: 29.4%
Leukocyte count: 11,000/mm^3
Platelet count: 60,000/mm^3

What is the most appropriate next step in management?