Pulmonary Embolism USMLE Step 1 Practice Question
A 68-year-old man with COPD presents to the emergency department with acute dyspnea and pleuritic chest pain that began 3 days after discharge from hospitalization for community-acquired pneumonia. He remains on supplemental oxygen and reports no leg pain or swelling. Vital signs: BP 128/82 mmHg, HR 104/min, RR 22/min, O2 saturation 91% on 2 L nasal cannula. Chest X-ray demonstrates a wedge-shaped opacity in the right lower lobe. An elevated D-dimer (2.5 mcg/mL) is obtained. The patient has a documented severe IgE-mediated contrast allergy precluding standard CT pulmonary angiography. Troponin is normal and ECG shows sinus tachycardia without ST changes. Which of the following is the most appropriate next diagnostic step?
Answer choices
- AProceed with contrast-enhanced CT pulmonary angiography after appropriate desensitization protocol
- BBedside transthoracic echocardiography to assess for right ventricular dysfunction
- CVentilation-perfusion scanCorrect answer
- DEmpiric anticoagulation based on clinical presentation and elevated D-dimer alone
- ERepeat chest X-ray in 48 hours to determine if opacity represents infarction
- FCompression ultrasonography of the lower extremities
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