Pneumonia vs Pulmonary embolism
How to tell Pneumonia and Pulmonary embolism apart when a board question makes them look alike.
Pneumonia is infectious alveolar filling; PE is sudden vascular obstruction with risk factors.
Side by side
Fever, productive cough, focal crackles, and infiltrate on chest imaging.
Sudden pleuritic chest pain, dyspnea, tachycardia, hypoxemia, clear lungs, and clot risk factors.
Infection fills alveoli with inflammatory exudate.
Thrombus blocks pulmonary arterial flow, causing dead-space ventilation.
Lobar infiltrate and leukocytosis support pneumonia.
High probability imaging, DVT signs, or hypoxemia disproportionate to chest film support pulmonary embolism.
The trap
Both cause tachypnea, hypoxemia, pleuritic chest pain, and can show infiltrates on chest imaging. The discriminating bedside features are onset and oxygen profile: pneumonia builds over days with fever, leukocytosis, productive cough, and a focal infiltrate matched to the hypoxemia; PE is sudden onset within minutes to hours, often with a clear chest film that is disproportionate to the hypoxemia, plus risk factors (recent surgery, immobility, malignancy, OCP, hereditary thrombophilia, recent long travel). Use Wells score or PERC rule plus D-dimer to triage low-probability patients; high-probability patients go straight to CT pulmonary angiogram.
Watch it explained
The repair move
When hypoxemia appears, decide whether the primary story is infection/infiltrate or clot risk plus sudden onset with relatively clear lungs.
Try a free question
CoreA patient has fever, productive cough, focal crackles, leukocytosis, and lobar infiltrate on chest x-ray. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Pneumonia. Fever, productive cough, and focal infiltrate point to pneumonia.
Why the other choices are tempting
- B. PE causes sudden dyspnea/pleuritic pain with clot risk and often clear lungs.
- C. Asthma causes episodic wheezing.
- D. Pneumothorax causes acute pleuritic pain and decreased breath sounds.
- E. Heart failure causes pulmonary edema and volume overload clues.
Flashcards
Tap a card to flip it.
What is the fastest separator for Pneumonia vs Pulmonary embolism?
Pneumonia is infectious alveolar filling; PE is sudden vascular obstruction with risk factors.
What clue should make you choose Pneumonia?
Fever, productive cough, focal crackles, and infiltrate on chest imaging.
Quick answers
What is the fastest way to tell Pneumonia from Pulmonary embolism?
Pneumonia is infectious alveolar filling; PE is sudden vascular obstruction with risk factors.
What is the key clue for Pneumonia?
Fever, productive cough, focal crackles, and infiltrate on chest imaging.
What is the key clue for Pulmonary embolism?
Sudden pleuritic chest pain, dyspnea, tachycardia, hypoxemia, clear lungs, and clot risk factors.
What is the common trap with Pneumonia vs Pulmonary embolism?
Both cause tachypnea, hypoxemia, pleuritic chest pain, and can show infiltrates on chest imaging. The discriminating bedside features are onset and oxygen profile: pneumonia builds over days with fever, leukocytosis, productive cough, and a focal infiltrate matched to the hypoxemia; PE is sudden onset within minutes to hours, often with a clear chest film that is disproportionate to the hypoxemia, plus risk factors (recent surgery, immobility, malignancy, OCP, hereditary thrombophilia, recent long travel). Use Wells score or PERC rule plus D-dimer to triage low-probability patients; high-probability patients go straight to CT pulmonary angiogram.