Clinical Scenario:

A 37-year-old female with a long history of multiple sclerosis presents to her primary care physician with complaints of dyspnea. She denies having a cough or fever but reports right-sided chest pain. Her medical history is significant for an episode of atrial fibrillation diagnosed in the emergency department two weeks ago, which resolved spontaneously without intervention. Due to spastic paraparesis, she is wheelchair-bound and has saccadic speech. She has no known allergies except for penicillin.

On physical examination, her blood pressure is 120/70 mmHg, and her heart rate is 110 beats per minute (regular). A chest x-ray reveals a right-sided pleural effusion. Therapeutic thoracentesis is performed, and the pleural fluid analysis reveals the following:

• Protein: 3.1 g/dL

• RBC count: 230/mm³

• WBC count: 150/mm³

• LDH: 220 IU/L

• Glucose: 100 mg/dL

Question:

Which of the following is the most likely cause of this patient’s pleural effusion?

• Congestive heart failure

• Hypoalbuminemia

• Pulmonary embolism

• Aspiration pneumonia

• Malignancy

 Correct Answer: Pulmonary Embolism

Multiple sclerosis (wheelchair-bound)

⬇️

 🧠 Immobility → ↑ Risk of Venous Stasis

Venous stasis + recent Atrial Fibrillation

⬇️ 

↑ Risk of Blood Clots 🧠

Blood clot (often in legs)

⬇️

 🧠 Potential for Pulmonary Embolism (PE)

Pulmonary Embolism (PE)

⬇️

🧠 Obstruction of Pulmonary Vessels

⬇️

Hypoxia & Inflammation

 ⬇️ 

↑ Capillary Permeability 🧠 

⬇️

Pleural Effusion Formation (exudative type)

Right-sided Chest Pain & Dyspnea 🧠 

⬇️

PE-related symptoms

⬇️

Air/Fluid in Pleural Space

⬇️

Compression Symptoms

Pleural Fluid Analysis:

• Protein: 3.1 g/dL ⟶ Exudate 🧠 (rules out transudative causes like CHF)

• RBCs 230/mm³ ⟶ Possible small hemorrhage 🧠 (supports PE)

• LDH 220 IU/L ⟶ ↑ LDH = Cell injury 🧠 ⟶ typical of PE or inflammatory process

• Glucose 100 mg/dL ⟶ Normal 🧠 (not consistent with infection or malignancy)

Explanation of Incorrect Options:

• Congestive Heart Failure (CHF):

• Typically transudative effusion ⟶ ⬇️ Protein, ⬇️ LDH (not seen here)

• Often bilateral effusions (not unilateral as in this patient)

• Hypoalbuminemia:

• Causes transudative effusion ⟶ ⬇️ Protein, ⬇️ LDH (not seen here)

• No specific risk factors in this patient for hypoalbuminemia

• Aspiration Pneumonia:

• Often presents with fever, cough ⟶ ⬆️ WBCs 🧠 (not seen here)

• Typically exudative, but with more inflammation (WBCs higher)

• Malignancy:

• Exudative effusion possible but usually associated with ⬆️ RBCs or abnormal cells 🧠

• No history of malignancy and no findings on exam suggestive of cancer

Flashcards

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Dr. Shoaib Ahmad