Review Question - QID 108657

A 59-year-old woman is brought to the emergency department by ambulance complaining of acute onset shortness of breath and a “racing pulse” that began after a 16-hour flight for a business trip. Her past medical history is significant for type 2 diabetes mellitus and for a hospitalization 2 months ago for a myocardial infarction, during which she received low-molecular-weight heparin following cardiac catheterization. Her current medications include metformin, aspirin, propranolol, and atorvastatin. She reports she has a family history of a “blood disorder" but does not have further details. On arrival, her temperature is 99.1°F (37.3°C), blood pressure is 112/74 mmHg, pulse is 96/min, respirations are 22/min, and oxygen saturation is 88% on room air. A chest radiograph is normal and an EKG shows sinus tachycardia. Lab results are obtained with the following results:

Serum:
Hemoglobin: 14.0 g/dL
Leukocyte count: 6,800/mm^3
Platelet count: 260,000/mm^3

After appropriate imaging is performed, intravenous unfractionated heparin is started for treatment of possible pulmonary embolus, and the patient is admitted to the hospital overnight. The next morning, the patient reports she is feeling better. Her temperature is 98.9°F (37.1°C), blood pressure is 118/73 mmHg, pulse is 88/min, respirations are 15/min, and oxygen saturation is 97% on room air. Repeat lab results are as follows:

Serum:
Hemoglobin: 13.5 g/dL
Leukocyte count: 7,200/mm^3
Platelet count: 87,000/mm^3

What is the most appropriate next step in management?