What diagnostic approach should be pursued urgently for suspected pulmonary embolism?

• A. D-dimer and CT pulmonary angiography (if D-dimer positive/clinical suspicion high).
• B. Chest X-ray only.
• C. MRI of the chest.
• D. Pulmonary function tests.

Answer: (A)

Diagnosing pulmonary embolism requires a rapid, risk-guided approach that uses imaging to confirm the presence of clots. Start by assessing pretest probability. D-dimer is a sensitive rule-out test in patients with low to intermediate probability: if the result is negative, PE is unlikely and further imaging may be unnecessary. If the D-dimer is positive or the clinical suspicion is high, proceed to CT pulmonary angiography, which directly visualizes clots in the pulmonary arteries and serves as the definitive imaging study in most cases. This combination allows urgent confirmation or exclusion of PE and guides timely treatment.

Chest X-ray can be normal or nonspecific and does not diagnose PE. MRI is not routinely used for acute PE due to practicality and sensitivity issues. Pulmonary function tests do not diagnose acute embolism or guide urgent management. If contrast intolerance or kidney issues exist, alternatives like a ventilation-perfusion scan may be considered, but CT pulmonary angiography remains the preferred diagnostic modality in most hemodynamically stable patients.