ZyraDoc #61 - October 01, 2026

A 54-year-old female presents with sudden-onset pleuritic chest pain, dyspnea, tachypnea, and hemoptysis 5 days following an elective major orthopedic procedure (total knee arthroplasty).

On physical examination, she is in moderate respiratory distress with tachycardia (118 bpm), tachypnea (28 breaths/min), SpO2 88% on room air, unilateral right lower extremity edema with calf tenderness, and an elevated Wells score indicating high probability.

Computed Tomography Pulmonary Angiography (CTPA) demonstrates a large vascular filling defect straddling the bifurcation of the main pulmonary artery (saddle embolus) with extension into the main pulmonary branches and right ventricular strain, confirming Acute Pulmonary Embolism.

Case Summary

Clinical Focus:

The diagnosis is Acute Pulmonary Embolism (PE) with signs of right ventricular strain.

Aetiology/Cause:

Thrombus formation in the deep veins of the lower extremities or pelvis (Deep Vein Thrombosis - DVT) dislodging and embolizing through the vena cava into the pulmonary arterial bed.
Driven by Virchow's Triad: venous stasis (postoperative immobility), endothelial injury (surgery/trauma), and hypercoagulability.
Obstruction of pulmonary blood flow leads to ventilation-perfusion (V/Q) mismatch, increased right ventricular afterload, and systemic hypoxia.

Clinical Features:

Acute dyspnea, tachypnea, pleuritic chest pain, and cough with hemoptysis.
Signs of hemodynamic collapse or RV failure: tachycardia, hypotension, elevated jugular venous pressure (JVP), and a loud pulmonic component of S2 (P2).
Lower extremity signs of concurrent DVT: asymmetrical calf swelling, warmth, and tenderness.

Diagnosis and Investigations:

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