A 48-year-old man presents with sudden onset of shortness of breath and pleuritic chest pain. He recently underwent knee surgery and has been immobilized. His oxygen saturation is 90% on room air, and he is tachycardic. A Wells score calculation suggests a high probability of pulmonary embolism. What is the most appropriate next diagnostic step?
✓ Correct Answer: Option D
Given the high pre-test probability for pulmonary embolism, a D-dimer is not helpful as it would likely be positive and still require further imaging. CTPA is the preferred diagnostic modality for confirming or excluding PE in patients with high clinical suspicion, especially those who are hemodynamically stable.