If a patient with suspected PE has an elevated D-dimer and tachycardia (HR 108), what is the next appropriate step?

If a patient with suspected PE has an elevated D-dimer and tachycardia (HR 108), what is the next appropriate step?

• A. Start LMWH
• B. Urinalysis
• C. CXR
• D. CT pulmonary angiography

Answer: (D)

Focus on how to confirm suspected PE rather than relying on D-dimer alone. D-dimer is very sensitive but nonspecific—many conditions can raise it. In a patient with suspected PE who also has tachycardia (increasing pretest probability), an elevated D-dimer cannot by itself confirm the diagnosis. The definitive next step is imaging to visualize the pulmonary arteries and establish or exclude the presence of a clot. CT pulmonary angiography is the preferred test in stable patients because it directly shows any embolus and also helps rule out other chest pathologies. Starting low-molecular-weight heparin would be appropriate after confirming PE or if there were compelling reasons to treat immediately (such as hemodynamic instability), but imaging comes first in this scenario to avoid unnecessary anticoagulation or missing an alternative diagnosis. A chest X-ray or urinalysis does not diagnose PE and would not be the next step for confirmation.

Focus on how to confirm suspected PE rather than relying on D-dimer alone. D-dimer is very sensitive but nonspecific—many conditions can raise it. In a patient with suspected PE who also has tachycardia (increasing pretest probability), an elevated D-dimer cannot by itself confirm the diagnosis. The definitive next step is imaging to visualize the pulmonary arteries and establish or exclude the presence of a clot. CT pulmonary angiography is the preferred test in stable patients because it directly shows any embolus and also helps rule out other chest pathologies.

Starting low-molecular-weight heparin would be appropriate after confirming PE or if there were compelling reasons to treat immediately (such as hemodynamic instability), but imaging comes first in this scenario to avoid unnecessary anticoagulation or missing an alternative diagnosis. A chest X-ray or urinalysis does not diagnose PE and would not be the next step for confirmation.