A patient presents with acute pleuritic chest pain and dyspnea; Wells score suggests a high probability of pulmonary embolism. What is the next best diagnostic test?

• A. CT pulmonary angiography (V/Q scan if CT contraindicated)
• B. D-dimer testing
• C. Chest radiograph
• D. Echocardiography

Answer: (D)

When there is a high pretest probability for pulmonary embolism, the next step is definitive imaging to confirm the diagnosis. D-dimer isn’t helpful here because a positive result is common with many conditions and cannot reliably rule out PE when the probability is already high. A chest radiograph is non-specific and won’t confirm PE, and echocardiography, while useful to assess right heart strain in massive PE or unstable patients, is not used to diagnose PE itself. The test that directly visualizes emboli in the pulmonary arteries and confirms the diagnosis is CT pulmonary angiography, assuming no contraindications to contrast. If contrast is not possible, a ventilation-perfusion scan is the alternative.