Pulmonary Embolism MCQ — NEET PG Practice Question | NEETPGAI
Pulmonary Embolism
medium
microscope Pathology
A 58-year-old man with a 10-day history of immobilization following orthopedic surgery develops acute dyspnea, chest pain, and tachycardia. CT pulmonary angiography confirms bilateral pulmonary emboli. Regarding the morphologic features and risk factors of thromboembolism in this patient, all of the following are correct EXCEPT:
A. Thrombi originating from deep veins of the lower extremity are the most common source of pulmonary emboli
B. Prolonged immobilization increases venous stasis and activates tissue factor, promoting thrombus formation
C. Virchow triad includes stasis, endothelial injury, and hypercoagulability, all of which are present in the postoperative period
D. Atherosclerotic plaques in the pulmonary arteries are the primary source of emboli in most PE cases
Explanation
Sources and Risk Factors in Pulmonary Embolism
Key Point
Atherosclerotic plaques in pulmonary arteries are NOT a primary source of PE. The vast majority of pulmonary emboli originate from deep vein thrombosis (DVT) in the lower extremities, not from in situ thrombosis of the pulmonary circulation itself.
Source of Pulmonary Emboli
Table
Source
Frequency
Mechanism
DVT (lower extremity)
90–95%
Venous thrombi dislodge and travel to lungs
DVT (upper extremity)
Rare
Catheter-related or malignancy-related
Right heart chambers
Rare
Mural thrombi in atrial fibrillation or MI
Atherosclerotic plaques (pulmonary arteries)
<1%
NOT a significant source
High-YieldNEET PG
PE is almost always a consequence of thromboembolism (thrombus formed elsewhere, then embolized), NOT in situ thrombosis of pulmonary arteries.
Virchow Triad in Postoperative PE
All three components are present in this patient:
1.
Stasis: Immobilization → venous stasis in lower extremity veins
Longest veins with slowest flow (popliteal, femoral, iliac)
Gravity-dependent pooling during immobilization
Surgical trauma and manipulation
Compression from swelling/casts
Clinical Pearl
In this postoperative patient, bilateral PE suggests massive thromboembolism, likely from bilateral lower extremity DVT or a large single thrombus that fragmented.
Other True Statements
Virchow triad: All three components are present in postoperative immobilization
Lower extremity DVT source: Correct; accounts for >90% of PE cases
Immobilization and hypercoagulability: Both stasis and tissue factor activation occur
Robbins 10e Ch 4
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