Pulmonary Embolism USMLE Step 1 Practice Question
A 64-year-old man presents to the emergency department 5 days after open reduction and internal fixation of a femoral neck fracture. He reports sudden onset of dyspnea and pleuritic chest pain. Vital signs: BP 95/60 mmHg, HR 118 bpm, RR 26/min, O2 saturation 88% on room air. Physical examination reveals unilateral leg swelling. Troponin I is elevated at 0.8 ng/mL (normal <0.04). Bedside echocardiography demonstrates RV dilatation with an RV/LV diameter ratio of 1.8:1 at the mid-papillary level. CT pulmonary angiography confirms bilateral pulmonary emboli. After initiation of intravenous unfractionated heparin, his systolic blood pressure decreases to 88 mmHg despite fluid resuscitation. Which of the following clinical findings most strongly supports the use of thrombolytic therapy in this patient?
Answer choices
- AElevated troponin I with RV dysfunction on echocardiography but systolic BP >100 mmHg
- BRecent surgery (5 days ago) with contraindication to thrombolytics due to bleeding risk
- CHemodynamic instability (systolic BP <90 mmHg) with imaging evidence of RV dilatationCorrect answer
- DPositive D-dimer and clinical suspicion for PE without confirmation by imaging
- EUnilateral lower extremity edema suggesting deep vein thrombosis as the embolic source
- FHypoxemia on room air with tachycardia but normal echocardiographic findings
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