A 48-year-old man with a history of recent long-haul flight presents to the emergency department with acute onset shortness of breath, pleuritic chest pain, and mild hemoptysis. His vital signs are HR 105 bpm, BP 120/80 mmHg, RR 24/min, SaO2 92% on room air. Physical exam is unremarkable except for mild tachypnea. ECG shows sinus tachycardia. What is the most appropriate next diagnostic step?

The correct answer to the question "A 48-year-old man with a history of recent long-haul flight presents to the emergency department with acute onset shortness of breath, pleuritic chest pain, and mild hemoptysis. His vital signs are HR 105 bpm, BP 120/80 mmHg, RR 24/min, SaO2 92% on room air. Physical exam is unremarkable except for mild tachypnea. ECG shows sinus tachycardia. What is the most appropriate next diagnostic step?" is Option C: CT pulmonary angiography (CTPA).

The other options — A) D-dimer, B) Ventilation-perfusion (V/Q) scan, D) Lower extremity duplex ultrasound — are incorrect for this USMLE Exam Prep question. As explained above: Given the high clinical suspicion for pulmonary embolism (recent travel, acute dyspnea, pleuritic pain, hypoxemia, hemoptysis), CT pulmonary angiography is the most appropriate initial diagnostic stu…