What is considered the gold standard diagnostic test for pulmonary embolism, though rarely performed?

• A. CT pulmonary angiography
• B. Pulmonary angiography
• C. D-dimer
• D. V/Q scan

Answer: (B)

Pulmonary angiography is the invasive catheter-based imaging of the pulmonary arteries after contrast, which directly shows filling defects caused by emboli. That direct visualization makes it the reference standard for diagnosing pulmonary embolism, even though it’s rarely done today because of its invasiveness and potential risks. Modern CT pulmonary angiography is noninvasive, widely available, and highly accurate, so it’s the preferred initial test in most cases. D-dimer is a sensitive screening tool that helps rule out PE in low-risk patients but is not diagnostic. A V/Q scan can detect mismatches between ventilation and perfusion and is useful when CT isn’t feasible, but it’s less definitive and more variable in interpretation.