A 45-year-old woman presents to the ED with sudden-onset dyspnea, pleuritic chest pain, and a cough. She recently underwent knee surgery. Her EKG shows sinus tachycardia and non-specific ST-T wave changes. D-dimer is elevated. Which of the following is the most appropriate next diagnostic step?

The correct answer to the question "A 45-year-old woman presents to the ED with sudden-onset dyspnea, pleuritic chest pain, and a cough. She recently underwent knee surgery. Her EKG shows sinus tachycardia and non-specific ST-T wave changes. D-dimer is elevated. Which of the following is the most appropriate next diagnostic step?" is Option C: CT pulmonary angiography (CTPA).

The other options — A) Chest X-ray, B) Ventilation-perfusion scan (V/Q scan), D) Lower extremity Doppler ultrasound — are incorrect for this USMLE Exam Prep question. As explained above: Given high clinical suspicion for pulmonary embolism in a stable patient with an elevated D-dimer, CT pulmonary angiography is the most appropriate and sensitive diagnostic test to confirm or rule ou…