A 26-year-old woman presents to the emergency department with acute onset pleuritic chest pain and dyspnea. She takes combined oral contraceptive pills. Vitals: temperature 98.9 F, blood pressure 118/70 mmHg, heart rate 110 per minute, respiratory rate 22 per minute, oxygen saturation 96 percent on room air. Her Wells score for pulmonary embolism is calculated as 4. What is the next best step in management?